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INTERLISP REFERENCE MANUAL
BY
WARREN TEITELMAN
contributions by:
A.K.HARTLEY
J. W. GOODWIN
BOLT BERANEK & NEWMAN
D. G. BOBROW
P. C. JACKSON
L. M. MASINTER
XEROX PALO ALTO RESEARCH CENTER
XEROX
PALO ALTO RESEARCH CENTER
3180 PORTER DRIVE/PALO ALTO/CALIFORNIA 94304
BOLT BERANEK & NEWMAN
Copyr;1:ht /') 1974
XEROX CORPORATION
Acknowledgements and .Background
INTERLISP (formerly BBN LISP) has evolved
from a succession of LISP systems
that began with a LISP designed and implemented for the DEC PDP-1 by D. G.
Bobrow and D. L. Murphyt at Bolt, Beranek and Newman in 1966, and documented by
D. G. Bobrow.
An upwards compatible version of this LISP was implemented for
the SDS 940 in 1967, by Bobrow and Murphy.
This system contained the seeds for
many of the capabilities and features of the current system:
a compatible
compiler and interpreter, 2 uniform error handling, an on-line LISP oriented
ed1tor,3 sophisticated debugging facilities,4 etc.
940 LISP was also the first
LISP system to demonstrate the feasibility of using software paging techniques
and a large virtual memory in conjunction with a list-processing system [Bob2].
DWIH, the Do-What-I-r1ean error correction facility. was introduced into the
system
in
1968
by
W.
Teitelman
[Tei2].
who
was
also
responsible
for
documentation for the 940 LISP system.
1~~--~~~---~~---~----------~------------------------------~------------------~-
D. G. Bobrow is currently at Xerox Palo Alto Research Center (PARe), D. L.
Murphy is with Digital Equipment Corp.
2
The preliminary version of the compiler was written by L. P. Deutsch. now
at Xerox PARCo This was considerably modified and extended by D. L. Murphy
before producing the final working version.
3
The original idea of a LISP oriented structure editor belongs to L. P.
Deutsch. The editor in its current form was written by W. Teitelman, now
of Xerox PARC.,
4
Designed and implemented by W.· Teitelman.
i
In
1970.
an upwards compatible version of 940 LISP called BBN LISp6 was
designed for the PDP-tO by D. G. Bobrow, D. L. Murphy, A. K. Hartley, and W.
Teitelman,
and implemented by Hartley with assistance from Murphy.
A.
K.
Hartley was also responsible for modifying the 940 LISP compiler to generate
code for the PDP-tO.
system
for
hardware
PDP-l0 designed and implemented by D.
the
Burchfiel,
D.
BBN-LISP ran under TENEX, a sophisticated time sharing
L.
Murphy,
T. _ R.
Strollo,
and R.
S.
G.
Bobrow,
D.
Tomlinson.[Bob1] With
paging and Z56K of virtual memory provided by TENEX,
practical
J.
it became
to provide extensive and sophisticated interactive user support
facilities, such as the progranuner's assistant [Tei4], CLISP [Tei5], and a more
sophisticated DWIM. all of whic:h were designed and· developed by W. Teitelman.
In 1971,
th~
block compiler was designed and implemented by D. G. Bobrow.
The
BBN-LISP Manual [Te,3] was written by.W. Teitelman, with contributions from A.
K..
Hartley and from J. W. Goctdwin, who also wrote TRANSOR and the special
arithmetic functions, as well a!) a number of other utility functions.
of
the system was changed from BBN-LISP to
maintenance and
develop~ent
of the
sys~em
INTERLISP in
1973,
The name
when
the
evolved into a joint effort between
Bolt Beranek and Newman, and Xerox Palo Alto Research Center.
The INTERLISP
reference manual was written by W. Teitelman, with contrlbutions from A. K.
Hartley,
J.
W.
Goodwin,
and
D.
G.
Bobrow.
The
cover
was
designed
by
Alice R. Fikes.
INTERLISP is currently the LISP' system used at Bolt Beranek and Newman, Xerox
Palo Alto Research Center, Stanford Research Instit.ute Artificial Intelligence
Center.
Information Sciences Ir.sti tute, and the Dendral Project at Stanford
University. in addition to being available at Computer Corporation of America
i--------------------------------------------------~-------------~-------------
The design, construction and documentation for BBN LISP was sponsored by
the Information Proces~ing Techniques Section of the Advanced Research
Project Agency, as was all of the subsequent work on the system that was
performed at BSN.
Since March 1972, the contributions made to the
development of the system by W. Teitelman, including the preparation of
this manual, were sponsored by Xerox Palo Alto Research Center.
ii
and Case Institute of Technology.
The total user conununity now comprises
approximately one hundred users.
INTERLISP is a continuously evolving system, both in response to complaints,
suggestions,
network,
and requests of the many users scattered throughout the ARPA
as well
as
the
long range
goals of the
individuals
primarily
responsible for the system, which are currently:
Person
Te itcTman
Xerox Palo Alto
Research Center
3180 Porter Dr.
Palo Alto, Calif. 94304
Responsible for
User facilities: i.e~, prettyprint, editor, break and trace,
adVising. printstructure, DWU1,
CLISP, programmer's assistant.
A. K. Hartley
Bolt Beranek & Newman
50 Moulton St.
Cambridge, Mass. 02138
Basic System: i.e., interpreter,
input-output, garbage collector; plus
all SUBRS, i.e. hand-coded machine language
functions such as PRINT, CONS, PROO, GO,
etc.; plus compiler.
J. W. Goodwin
Bolt Beranek & Newman
50 Moulton St.
Cambridge, Mass. 02138
Special Arithmotic Functions: e.g.
LOG, SIN, SQRT, etc.; plus functions
for accessing TENEX capabilities
such as SUBSYS, FILDIR, et al.;
plus TRANSOR as well as various
utility functions such as LOADFNS,
SORT, etc. (as indicated in the text
of this manual).
w.
*
The preparation of this manual has involved the efforts of several persons at
Xerox PARC, whom I specifically want to mention. and to express my appreciation
for their support through this arduous, and at times seemingly endless task.
Thank you Suzan (Jerome), Janet (Farness), Peter (Deutsch),
Larry (Tesler).
I couldn't have done it without
Bob (Walker), and
you~
Warren Teitelman
Palo Alto
December, 1973.
ii1
TABLE OF CONTENTS
SECTION 1: Introduction
SECTION 2: Using INTERLISP
Using the INTERLISP Manual •••.•.• ~ •••••.••• ~......
Using the INTERLISP System on Tenex •.•••..••••••••
1
4
SECTION 3: Data types, Storage Allocation, and Garbage
Collection
Data Ty·p,es ••••••••••••••••••••••••••••••••• ~ ••••.••
Literal Atoms ...•••...••..•..••..••••••••..••
Pnames ..•.•. , ••.•••••••••••••••• '•••••••••••••
Numerical Atoms ...•......•.....•...•••••••..•
Li s. t s ..... ~ .............•....................
Arrays ',.. " ....... ~ ..' ......................... .
St.r·ings .••.•••••••••••••••••.••••••••••••••••
Storage Allocation and Garbage Collection ••••.•.•.
Shared INTERLISP .................................. .
1
2
4
4
7
8
9
11
14
SECTION 4: Function Types and Impltcit PROGN
Exprs ..........~ ....•.••..•
*' •••••••••••••••••••••••
1
Compiled Functions ••••..•.••.••.••••..••••••••••••
Function Type ...•..••, •.••••••••••.•••••••••••.•. "c' •.•••••
2
PROGN •••••••••••••••• •". ~ ••••••••••••••••••••••••••
3
4
Implicit PROGN
4
SECTION 5:
Primi~ive
.. ................................ .
~
Functions and Predicates
Primitive Functions ..•.••.•••••••••.••••••••••••••
RESETVAR and RESETFORM .•..••..•••••••••••••••••••.
Predicates and Logical Connectives .••.••••••••••••
1
9
11
SECTION 6: 'List Manipulation and Concatenation
SECTION 7: Property Lists and Hash Links
Property Lists ..•.......••••••••••.••.•••.•••••••••
1
Hash Links ....... ~ .. ~ ..............~... •.. .. . . . . •. •
4
llash Overfiow' • • . • . . • • • • . • • • • • • • • • • • • • • • • • • • • •
7
i
TABLE OF CONTENTS (cont.)
SECTION 8: Function Definition and Evaluation
SECTION 9: The INTERLISP Editor
Introduction ............•.•••••••••.••••••••••••••
Commands for the New User .•....•..•.••...•.••••\ •.•
Attention Changing Commands •••••..••••••••••••••••
Local Attention Changing Commands ••••••••••••
Commands Tha t Search ....•....•.••••.•••••••••
Search Algorithm .........•••......•.•.•.
Search Commands' ......••.•.••••••••••••••
Location Specification •...•.••••••••••••
Commands That Save and Restoro the
Edit Chain •••••••
111
••••••••••••••••••••••••
Commands That ~lodify Structure •.......•...•••••••.
Implementation of Structure Modification
Commands •••••••••••••••••••
III. • • • • • • • • • • • • • •
The A, B, : Commands ...••.....•..•.••.•••••••
Form Oriented Editing and tho Role of UP •••••••
Extract and Embed •......••••..••••••.••••••••
1
10
15
15
21
23
25
28
34
36
37
39
43
45
Commands That "Move Parentheses" •...•••••••••
48
51
TO and THRU ••••••••••••••••••••••••••••••••••
54
l'he MOVE Command •••••••••••••••••••••• " ••••••
The
Commands
Conunands
Commands
R Command ..........••• -• ••••••••••••••••••
That Print ......•••.•.•••••••••••••••••••
That Evaluate •.•••.••••••••••••••••••••••
Tha t Tes t ..•.•.••••.••..•••.•••..•.••••••
60
62
64
...••••.••..•••••••••••••••.••••••••••••••••
67
Niscellaneous Commands •.•••....••••.••••.••.••••••
70
~Iacros
UNDO ••••••••••••••••••••••••••••••••••••••••••••••
EDITDEFAUL T •••••••••••••••••••••••••••••••••••••••
Editor functions
57
78'
80
83
SECTION 10: Atom, String, Array, and Storage Manipulation
Pnames and Atom Manipulation ..••...••.•.••••••••.•
String functions ..........••.•....••••.••••..•.•••
Searching Strings ........•...••.......••••.••
String Storage ...•..•.••••.•.•••••••••.•.••••
Array Functions ......••....••.••••••••••••••.•••••
Storage Functions ....•••...•....••.•••••..•.••••••
1
5
8
11
12
14
SECTION 11: Functions with Functional Arguments
SECTION 12: Variable Bindings and Pushdown List Functions
The Pushdown List and the Interpreter •.•.•••••.•••
The Pushdown List and Compiled Functions ••••••••••
Pushdown List functions ..•..•.....••••••••••••••.•
The Pushdown List and Funarg ••••••••••••••••••••••
i1
3
5
6
11
TABLE OF CONTENTS
(corit~)
SECTION 13: Arithmetic:Ftinctions
General Comments
Integer Arithmetic
Floating Point Arithmetic •••••••••••••••••••••••••
Mixed Arithmetic
Special Functions
Reusing Boxed Numbers - SETN .•••••••••.•••••••••••
Box and Unbox, ••
.................................
o' • • • • • • • • • • • • • • • • • • • • • • • • • • • • ' • • • • • •
1
2
6
7
8
10
12
SECTION 14: Input/Output Functions
.................................. .
Files ....... . .
Addressable Files .•••••••••••••••••••••••••••
JFN Functions
Input Functions
Output Functions
Printlevel
Input/Output Control Functions .~ .••••.•••••.•••••.
Line-buffering and CONTROL •••••••••••••••••••
Special Functions
Symbolic File Input ••••...•••.••••••••••••••••••••
Symbolic File Output
PRETTYPRINT
Comment Feature
PRETTYDEF
Special PRETTYPRINT Controls •••••••••••••••••
File Package
"
.............................
......... .................... .
......................................
... ................................. .
'
'
1
5
8
10
18
19
21
23
26
27
29
29
30
31
38
44
SECTION 15: Debugging - The Break Package
Debugging Facilities
BREAK 1 ........•..•..
Break Commands
Brkcoms ..... .
Brkfile
Breakmacros
Break Functions
BREAKIN
1
'4
......................................
..... ............. ............. .
...................................
'.'
'
7
14
15
15
16
19
SECTION 16: Error Handling
Unbound Atoms and Undefined Functions •••••••••••••
Teletype Initiated Breaks .••.•....••, ••••••••••••••
Control U •.•••.
Control B ..... . .
Control E
Other Types of Errors ....•...•.••.••••..••••••••••
Breakcheck - When to Break' ••.•••••••••••••••••••••
Error Types
Error Handling by Error Type •••••••••••••••••
Error Functions
.......................... .
iii
1
2
Z
3
3
4
4
7
10
12
TABLE OF CONTENTS (cont.)
SECTION 17: Automatic Error Corr 9ction - Tho DWIM Facility
l
Introduction
Interaction wi th DWIM ......•....•...•.•..•..••.•.•
Spellirig Correction Protocol .•...•••..•••••••
Parentheses Errors Protocol •.••••...•.••••.•••
Spelling Correction .... ~ .......••.••••.•..••••••••
Spelling Lists
Error Correction
Unbound Atoms
Undefined Car of Form .....•..••••.••..••••.••
Undefined Function in Apply ...•••..••••••••••
DW I ~IUSERFN
Spelling Corrector Algorithm .••.••.••••••.•••••• ~.
..............................
• • • • • • • • • • • • • • • • • • • • • I."• • • • •
DWI~1
Functions ........................... ., ......~ ..
1
5
5
7
10
11
14
16
17
18
19
20
23
SECTION 18: The Compiler and Assembler
The Compiler ..... .
Compiler Questions
Nlambdas ......... .
.............................. .
1
3
5
Globalvars ....................................... .
6
Compiler Functions
RECONPILE
Open Functions
Compiler Macros
FUNCTION and F~nctlonal Arguments ..•.•..••••..••••
Block Compiling
Specvars
Localfreevars
Retfns
Blkapplyfns
Blklibrary
Linked Function Calls
Relinking
The Block Compiler
BLOCKCONPILE
Block D~clarations ..•..•.••••.•••••.•..•...
7
10
13
14
16
.............................
BtO~lPL ..................................... .
I1RECOMPILE
Compiler Structure
ASSEMBLE ...... .
l.AP
Us ing ASSE~IBLE
Miscellaneous .............•.•.•.
Compiler Printout and Error Messages ••.•••••••••••
o •• o • • • • • • • • • • • • • •
17
18
18
20
20
21
21
25
26
27
28
30
31
34
35
40
46
41
48
SECTION 19: Advising
Implementation of Advising ••.•••••••••••••••••••••
Advise Functions ..•..•.•
0
•••••••••••••
iv
0
•••••••••••
2
5
TABLE OF CONTENTS
(~ont.)
SECTION 20: Printstructure and Interscope
Printstructure ...•....••.•.•.••••...••...•.....•.•
1
Intcrscope ............................................
10
SECTION 21: Miscellaneous
Measuring Functions •..•..
~........................
1
BR EAK rlQWN. • •••••••••••••••••• ,.....................
EDI TA ••••••• ;'. • ~" • • • • • • • • • •~. • • • • • • • • • • .'. • • • • • • • • • • •
5
8
Input Protocol ...•..........•....•..•..••••.•
F.DITA commands and variables ................•
Interfork Communication .•.........•.•.•••••.•.••••
10
12
17
Subsys .................•"............•....•..••.•,..
18
Miscellaneous TENEX Functions ......••... ~.........
Printing Reentrant and Circular List Structures
21
24
SECTION 22: The Programmer's Assistant and LISPX
Introduction .......•...•.•.•...•••.•••.•••....•••.
1
Overview ........ ,", ...... ., ....'......................
6
Event Specification ...........•••.....•. ~.........
History, Commands ................•...•..••••••.•.••
Implementation of REDO, USE, and FIX .•......•
History Commands Applied to History Commands.
HistorY Commands That Fail...................
~lore History Commands •.........•....••.•...••
Miscellaneous Features and Commands .....••..•.•••.
11
14
17
19
20
21
28
Undoi.ng ...... :...............................•..... ,.....
38
Testmode .........•...•••..•....••••••••••.•.••
41
Undoing out of order ...........•.....•...•.••
SAVESET .................. '. • . . . . . . • . .• . . . . . . . .
Format and Use of the History List .•....•.•••.•...
LISPX and READLINE •........••..•..•.•..•.•.•..••..
Functions ................•..•.••••...••.•••••.•.••
Tho Editor and the Assistant ..•••.•••••...•.•..•.•
42
43
44
47
48
Statistics ........... .......
Greeting and
Use~
e·.......................
Initialization ..••.••••.•••.••••
v
~1
63
64
TABLE Of CONTENTS (cont.)
SECTION 23: CLISp·- Conversational LISP
Introduction
CLISP Syntax ...•.............•..•.........••...•••
Infix Operators ...........•.•.......•..•..•..•••••
Prefix Operators ..•........•..•......••••...•..••.
Constructing l.ists - the <.> Operators ..••..••••••
IF, TIIEN. ELSE
Iterative Statements ..........•..•••.....••.•••••.
Errors in Iterative Statements .•.•.....•.••.•
Defining New Iterative Statement Operators
CLISP Translations .....•••••..••.•..••.•.••••••••.•
Declarations .............••••••••.••.•••.•.•••.•.•
Local Declarations ..•...•••.•..•....•.••...•
The Pnttern Match Compiler ..•••••..•••••••••••.•••
Element Patterns ..•..•...•••.•••.....•••••....
Segment Patterns ••..•••..•....••.•.•••••.•.••
1
9
10
13
16
17
18
27
28
30
33
35
36
39
41
Assignments ..•.•.•.•••..••••••.••.••••.••.•••
43
Place-markers ...••.•••..•••••••••••••••••.•••
I~cplacements .•...•••.•..•.••...••.••.•.••••••
Reconstruction ....•••••.••••••..••••••.••••••
Record Package ........•.•.••...•..••••..•••••••••.
Record Declarations ...•........••••....••...•
CREATE
Implementation ....• ~ .•..•.••..•...••...•••...
CLISPIFY
DWHtIFY
Compiling CLISP
Operation
CLISP Interaction with User .•••..• ~ .•.•..•••••••••
CLISP Internal Conventions ....•••..•.••.••.••.••••
CLISP Functions and Variables .•••.•.•.••.•••••••••
44
44
46
48
...................................
••••••••••••
tI
••••••••••••••
It
• • • • • • •: • • • • • • • •
51
55
57
58
61
63
64
67
68
71
APPENDIX 1: TRANSOR
Introduction
Using TRANSOR
The Translation Notes
TRANSORSET
Controlling the sweep
1
3
4
8
14
APPENDIX 2: INTERLISP Interpreter
APPENDIX 3: Control Characters
MASTER INDEX
vi
SECTION 1
INTRODUCTION
This document is a reference manual for INTERLISP, a LISP system currently
implemen,ted on the DEC POP-tO under the BBN TENEX time sharing system.[Bob1]
INTERLISpl is designed to provi~ethe user access to the large virtual memory
allowed by TENEX, with a relatively small penalty in speed (using special
paging techniques described in [BobZ]).
Additional data types have been added,'
including strings, arrays, and hash association tables (hash links) (Sections 7
and
10).
interpreter.
The
system
includes
a
compatible
compiler
(Section
18)
and
Machine code can be intermixed with INTERLISP expressions via the
assemble directive of the compiler.
The compiler also contains a facility for
"block compilation" which allows a group of functions to be compiled as a unit,
suppressing
internal
names.
Each successive
level
of computation,
from
interpreted through compiled, to block-compiled provides. greater speed at a
.cost
of debugging ease .
INTERLISP ~as been designed to be a good on-line interactive system.
Some of
the features provided include elaborate debugging facilities with tracing and
conditional breakpoints (Section 15), and a sophisticated LISP oriented editorwi thin the system (Section 9).
Utilization of a uniform error processing
through user accessible routines (Section 16) has allowed the implementation of
DWIM, a
!!o-~at-! -~ean
facility, which automatically corrects many types of.
errors without losing the context of computation (Section 17).
1.1
The CLISP
facility (Section 23) extends the LISP syntax by enabling ALGOL-like infix
operators such as +, -, -, /,
=, .,
AND, OR, etc., as well as IF-THEN-ELSE
statements and FOR-WHILE-DO stiltements.
CLISP expressions are automatically
converted to equivalent LISP for'ms when they are first encountered,.
CLISP also
includes list construction operutors, as well as a LISP oriented pattern match
compiler.
A novel and useful facility lof the INTERLISP system is the programmer's
assistant (Section 22), which monitors and records all user inputs.
The user
can instruct the progranuner I s ,assistant to repeat a particular operation or
sequence of operations, with
specified operations.
modifications, or to UNDO the effects of
po~.sible
The goal of the programmer's assistant, OWIH, CLISP.
etc. is to provide a programming environment which will "cooperate" with the
user in the development of his programs, and free him to concentrate more fully
on the conceptual difficulties and creative aspects of the problem he is trying
to solve.
To aid in converting to INTERL ISP programs written in other LISP dialects,
e.g., LISP 1.5, Stanford LISP,
accepts
transformations
(or
I~e,
have implemented TRANSOR, a subsystem which
can
operate
from
previously
defined
transformations), and applies these transformations to source programs written
in another LISP dialect, producing object programs which will run on INTERLISP
(Appendix 1).
In addition, TRANSOR alerts the programmer to problem areas that
(may) need further attention.
TRANSOR was used extensively in converting from
940 LISP to BBN-LISP on the PDP-l0.
A set of transformations is available for
converting from Stanford LISP and LISP 1.5 to INTERLISP.
A complete format directed list processing system FLIP [Teil], is available for
use within INTERLISP.
Although we have tried to be as clear and complete as possible, this document
1.2
is not designed to be an introduction to
LISP~
Therefore, some parts may only
be clear to people who have had some experience with other LISP systems.
good introduction to LISP has been written by Clark Weissman [Weil].
A
Although
not completely accurate with respect to INTERLISP. the differences are small
enough to be mastered by use of this manual and on-line interaction.
Another
useful introduction is given by Berkeley [Bert] in the collection of Berkeley
and Bobrow [Ber2].
Changes to this manual will be issued by replacing sections or pages, and
reissuing the index and table of contents at periodic intervals.
In addition,
the manual will be maintained on-line, and up to date versions of any or all
chapters will be available in the form of TENEX files from W. Teitelman at
Xerox PARC.
1.3
Bibliography
[Bert]
Berkeley. E.C .• "LISP, A Simple Introduction" in Berkeley. E.C. and
Bobrow, D.G. [Ber2].
[Ber2]
Berkeley, E.C., and Bobrow, D.G. (editors), The Programming Language
LISP, its Operatiol!! and Applications, MIT Press, 1966e
[Bobl]
Bobrow, D. G., Burchfiel, J. D., Murphy, D. L., and Tomlinson, R. 8.
nTENEX, a Paged Time Sharing System for the PDP-I0",
Communications of :the ACM, March, 1972.
[Bob2]
Bobrow, D.G., and Murphy, D.L. "The Structure of a LISP System Using
Two Level Storage", Communications of the ACM, VIS 3, March 1967.
[ Bob3]
Bobrow, D.G., and Wegbreit, B. "A Model and Stack Implementation for
Mul tiple EnvironmEmts" (to be published), Third International
Joint Conference ~!! Artificial Intelligence, August 1973.
[Meel]
McCarthy, J. et ale
[Murl]
Murphy, .D.L.
"Stora"e Organization and Management in TENEX",
Proceedings of Fal~ Joint Computer Conference, December 1972.
[8mi1]
8mi th, D. "MLISP" Art;ificial
University, October 1970.
[Teit]
Teitelman, W. FLIP, A format Directed List Processor in LISP, BBN
Report, 196-:;-:- -
[Tei2]
Teitelman, W. "Toward a Programming Laboratory" in Walker, D. (ed.)
International Joint Conference on Artificial Intelligence, May
1969.
---
[ Tei3]
Teitelman, W., Bobrow, D.G., Hartley. A.K. Murphy, D.L.
BBN-LISP
TENEX Reference Manual, Bolt Beranek and Newman, July 1971, first
revision, Febru8r~1972, second revision August 19,72.
[Tei4 ]
Teitelman, W. "Automatl!d Programmering - The Programmer's Assistant",
Proceedings of the Fall Joint Computer Conference, December 1972.
[Tei5 ]
Teitelman, W.
"CLISP - Conversational LISP"~ Third International
Joint Conference ~l Artificial Intelligence, August 1973.
[Weil]
Weissman, C. LISP 1.5
LI;SP 1.5 Programmer's Manual, MIT Press, 1966.
~rimer,
Intelligence Memo No.
Dickenson Press (1967).
1.4
135 Stanford
SECTION 2
USING INTERLISP
2.1' Using the INTERLISP'Manual ..; ~:Format, Notation, and Conventions
The
INTERLISP
sections.
manual
Each
is
divided' into
separa'te
more
section· ig paginated ,independently,
updates 'of sections.
or
to
less
independent
facilitate
issuing
Each sec'tion "cont'ains an index to ' keywords, functions,
and variables contained in that section.
In addition, there is a composite
index for the entire manual, plus several appendices and a table of contents.
Throughout the
manual~
terminology'and conventions will be offset from the text
and typed in italics, ·frequently at the beginning of a section.
one such notational
~onvention
For example,
is:
The' names of functions and ,,«riables are written in lOUler case and underlined
when theu appear in the text.
Examples:
Meta-LISP notation is used Jor describing Jonms.
member[x;y] is equivalent t'o (MEMBER X Y), 'member[car[x];FOO] is
equivalent to (MEMBER (CAR X) (QUOTE FOO».
Note that. in meta-LISP notation
lower case variables are evaluated, upper case quoted.
. notation is used to, distinguish between £!!!!:! and lli.!.:
e.g., if !=(A B C).
is (FOO A B C).
Similarly, l
(FOO x) is (FOO (A B C», whereas(FOO • x)
In other words, !
is cadr of (FOO x) but cdr of (FOO • x).
is caddr of, (FOO x'Y)','but cddr of (FOO x • y).
2.1
Note that this
convention
is
i.e., (FOO . (A B C»
in
fact
followed
by
the
read
program,
and (FOO A B C) read in as equal structures.
Other important conventions art:
TRUE in INTERLISP means not NIL.
The purpose of this is to
allo,~
a single function to be used both for the
computation of some quantity, and as a test for a condition.
For example, the
value of member[x;y] is either NIL. or the tail of 1.. beginning with !.
Similarly, the value of !!.!: is the' value of its first TRUE, i.e.,. non-NIL,
expression, and the. value of !Jrld is either NIL, or the value of its last
expression.
Although most lists terminate in NIL. the occasional list that ends in an atom,
e.g •• (A B . C) or worse, a nUlmer or string, could cause bizarre effects.
Accordingly. we have made the fol.lowing implementation decision:
All junction.s that iterate throl!lgh a li.st. e.g •• member. length. mapc etc.
terminate bll an nli.s.tp checlc.. 1'ather than the conventional nuLl-checlt, a.s a
.sajetll precaution again.st encouTiltering dat.a tupes which might cause infinite
cd r Loop.s. e. g .• s tri ngs. number~;. arraus.
t
Thus, member[x;(A B . C)]=member[x;(A B)]
reverse[(A B . C)]=reverse[(A B)]
append[(A B • C);y]=append[(A B);y]
For users with an application requiring extreme efficiency,1 we have provided
fast versions of memb, last, n1;h, !!!!!£. and length which compile open and
i---~-~-I~--;;;;;-~;~-~~--;;;~;;;d'-~~-~~;~--;~;-~~;;;~~;~~~:-~~--;;;;;;-;;~~~;;;
about 12, although both gener'ate only one word of code.
2.2
terminate on NIL checks. and therefore may'cause infinite cdr loops if given
poorly formed arguments.
However. to help detect these situations,
fmemb,
flast ~ fnth, fassoC, and 'flength 'all generate errors when interpreted if their
argument ends 1n a non-list other'than NIL, e.g. BAD ARGUMENT - FLAST.
Most Junctions that set sustem parameters. e.g .• printleueZ. linelenath, radix,
etc .• return as their ualue the old setting. 1/ giuen NIL as an argument. theu
return the current ualue without changing it.
All SUBRS, i. e., hand coded junctions. such as read, print, eu'al, ~, etc.,
have 'argument names' (U V W) as described under arglist, Section 8. Howeuer,
Jor tutorial purposes ,more suggestille names are used in the descriptions 01
these Junctions, in the text.
Most Junctions whose names end in ! are predicates. e.g. numberp, tailp. exprp,
most JUri,cttons whose names' end in !l. are nZambda's. t.e., do not require quoting
their arguments, e.g., setg, define,. nlsetg .
•• ~ is equal to 1/." means equal(x,IIJ is true. as opposed to"! t's !!l. to 1/."
meaning eq(x,uJ is true. i.e .• !. and II. are the same identical tiSP pointer.
When neru literal atoms are created (bu the read program. pack. or mitatom). theu
are provided with a junction dejinition cell initialized to NI£ (Section 8), a
ualue cell initialized to the atom NOBIND (Section 16), and a propertll list
initialized to NIL (Section 7). The junction dejinition cell is accessed bll
the functions getd and putd described" in Section 8. The ualue cell oj an atom
is car oj the atom. and its propertu list is cdr 0/ the atom. In particular,
£l!!. oj NI£ and cdr oj NI£ are alwalls NIL. and thesustem will resist attempts
to change them.
The term lis t rejersto anu structure created bU one or more con.se.s • i.e. it
doe.s not hcive to end in NIL. For example, (A . B) is a list. The Junction
listp, Section 6. is used to test lor li.sts. Note that not being a list does
not nece.ssarily impZu an atom. e.g .• strings' and aTraus are not lists. nor are
theyatom.s. See Section 10.
Many .sy.stem Junctions haue extra optional arguments jor internal use that are
not de.scribed in the writeups.
For example, readline is' described as a
Junction oJ no arguments. but arglist(READLINE} returns (LINE LISPXFLG). In
such cases, the user should just ignore the extra arguments.
.
INTERLISP departs from LISP 1.5 and, other LISP dialects in that car oj a Jorm
is neuer
evaluated~
In other words, if £!!. of a form is not an atom with a
function definition, and not a function object, i.'e. a list
LAMBDA, NLAMBDA, or FUNARG, an error is generated.
must be used if the name of a function is to be
functional arguments are applied.
2.3
~
~
of which is
or !ru!.!I* (section 8)
computed as for example, when
2.2
Using the INTERLISP System on TENEX - An Overview
Call INTERLISP by typing LISP followed by a carriage return.
INTERLISP will
type an identifying message, the date, and a greeting, followed by a
'~'.
prompt
top
character
indicates
INTERLISP executive,
that
the user
called !!'y'algt,
line, it is evaluated;
the second.
eval and
Rtalking
toR
the
(for historical reasons),
indicates the user is talking to TENEX.
inputs in ei ther eval or
is
This
level
just as
I@'
evalgt 'calls lispx which accepts
!..I!.l!.!I format: if just one expression is typed on a
if two
4~xpressions
are typed. the first is .!.I!.P1I-ed to
!..I!.l!.!I art. described in section 8.
value is typed, followed by
~
In both cases. the
indicating INTERLISP is ready for another input.
INTERLISP is normally exited via the fUnction LOGOUT. i.e.. the user types
LOGOUT( ). However. typing contr"ol-C at any point in the computation returns
control immediately to TENEX.
The user can then continue his program with no
ill effects with the TENEX CONTINUE comand, even if he interrupted it during a
Or he can reenter his program at evalqt with the TENEX
garbage collection.
REENTER command.
The latter is DEFINITELY not advisable !l the Control-C
typed during !! garbage
computation
will
collec1~ion.
return
control
~
Typing control-D at any point during a
to
evalgt.
If
typed
during
a
garbage
collection, the garbage collection will first be completed, and then control
will
be
returned
to
INTERLIiSP' s
top
level,
otherwise,
control
returns
immediately.
When
typing to the
INTERLISP read program,
typing a control-Q will cause
INTERLISP to print 'II' and clear the input buffer, i.a., erase the entire line
up to the last carriage return.
Typing control-A erases the last character
typed in, echoing a \ and the erased character.
beyond the last carriage return.
Control-A will not back up
ControI-O can be used to tmmedtatelu clear
2.4
the output buffer, and rubout to immediatel,l clear the input buffer. 2
In
addi tion, typing, control-U (in most cases) will cause the INTERLISP editor
(Section 9) to be called on the, expression being read, when the read 1s
completed.
Appendix 3 contains a list of all control characters,
and a
reference to that part of the manual where they are described.
Since the INTERLISP read program is normally line-buffered to make possible the
action
of control-Q,a
the user must
type
•
carriage
return
b.fore
any
characters are delivered to the function requesting input, e.g.,
.. E T.>
T
4
However, the read program automatic.llll supplies (and prints) this carriage
return when a matching right parenthesis is typed, .aking it unnecessary for
the user to do so, e.g.,
"CONS(A B)
(A • B)
The INTERLISP read program treats square brackets as 'super-parentheses' ': a
right square bracket automatically supplies enough right parentheses to match
back to the last left square bracket (in the expression being read), or if none
has appeared, to match the first left parentheses,
e. g. ,
(A (B (C]= (A (B (C»),
(A [B (C (0] E)·(A (8 (C (0») E).
2--~-~-----------~---------------~--~-~--------------------------~------------~
The action of control-Q takes place when it is read. If the user has
'typed ahead' several inputs, control-Q will only affect at most the last
line of input. Rubout however will clear the entire input buffer as soon
as it is typed, i.e., even during a garbage collection.
8
Except following control[T], see Section 14.
"
'.,' is used throughout the manual to denote carriage-return.
2.5
Thus to input an atom containing
% is the universal escape character for read.
ABX (C or
a syntactic delimiter, precede it by X, e.g.
xx.
See Section 14 for
more details.
Most of the "basics" of on-lillie use of INTERLISP, e.g. defining functions,
error handling,
editing,
saving your work,
following brief console session.
1.
are
illustrated
in the
Underlined characters were typed by the user.
The user callslNTERLISP from TENEX,
greeting.
etc.,
The prompt character
~
INTERLISP prints a date,
and a
indicates the user is at the top level of
INTERLISP •.
2.
The user deC·ines a functi')n,
INTERLISP,
functions
fact,
for computing factorial of n.
are defined via DEFINE or DEFINEQ,
In
(Section 8).
Functions may independently evaluate arguments, or not evaluate them, and
spread their arguments, or not spread them (Section 4).
The function fact
shown here is an example of an everyday run-of .. the-mill function of one
argument, which is evaluated.
3.
The user "looks" at the lFunction definition.
Function definitions in
INTERLISP are stored in a special cell called the function definition cell,
which is associated with the name of the function (Section 8).
is accessible via the two functions, getd and putd,
putd).
Note
that
expression, i.e.
form for eval.
4.
the
an
input
consisting
and defineq use
of
a
single
(GETD (QUOTE FACT», which was therefore interpreted as a
The user could also have typed GETD(FACT).
The user runs his function.
by
typed
u~)er
('def~ne
This cell
DWI" (Section 17).
Two errors occur and corrections are offered
In each case, the user indicates his approval, DWI"
makes the correction, i.e.
actually changes. the definition of fact, and
then continues the computation.
2.6
@LISP,>
INTERLISP-I0 11-17-73 •••
GOOD EVENING.
(LAMBOOA (N) (COHO «EO N 0) NIL)
Z
(T (ITIMES H (FACTT (SUBI H]
(fACT)
~(GETO (QUOTE FACT»
3
(LAMBOOA (H) (CONO «EQ H 0) NIL) (T (ITIHES N (FACTT (SU81 N»»»
~FACT(3)
.
.
4
LAMBOOA [IN FACT] -> LAMBDA? !ESl
FACTT [IN FACT] -> FACT? !ESl
~OEFINEQ«FACT
NON-NUMERIC ARG
NIL
IN ITIHES
5
,
(BROKEN)
:BT,>
ITIMES
CONO
FACT
CONO
FACT
CONO
FACT
**TOP**
:N,>
1
:EOITF(FACT)
EDIT
*(R NIL 1)
*OK,>
FACT
:RETURN 1.>
'BREAK' = 1
8
1-
6
~PP
9
10
11
FACT,>
12
(FACT
[LAMBDA (N)
(CONO
« EQ NO)
1)
FACT
(T (ITIMES N (FACT (SUBI N])
~PRETTYOEF«FACT)
FACT. ,I
13
14
FACT)
2.7
5.
An error occurs that OWl" cannot handle. and the system goes into a break.
At this point. the user can type in expressions to be eval-ed or apply-ad
exactly as at the top level.
The prompt character ':' indicates that the
user is in a break. i.e. that the
conte~t
of hi$
c~mputation
is available.
In other words. the system is actually "within" or "below" the call to
itimes in which the error occurred.
6.
The user types in the break command, BT, which calls (or a backtrace to be
printed.
In INTERLISP, interpreted and
compil~d
code (see Section 18 for
discussion of the compiler) are completely compatible, and in both cases,
the name of the function that was called, as well as the names and values
of its arguments are stored on the stack.
The stack can be searched and/or
modified in various ways (see Section 12).
Break commands are discusse:d in Section 15, which also explains how the
user can "break" a particular function, i.e. specify that the system go
into a "break H whenever a 'certain function or functions are called.
that
point the user can c!xamine the state of the computation.
At
This
facility is very useful for debugging.
7.
The user asks for the value of the variable
or binding.
rr.
i.e. the most recent value,
The interpretEtr will search the stack for the most recent
binding, and failing to find one, will obtain the top level value from the
atom's value cell, which is
£![
of the atom (Section 3).
If there are no
bindings, and the value cell contains the atom NOBINO, an unbound atom
error is generated (Section 16).
8.
The user realizes his error. and calls the editor to fix it.
the system is
~till
(Note that
in the break.) The editor is described at length and in
detail in Section 9.
It is an extremely useful facility of· INTERLISP.
Section 9 begins with a simple introduction designed for the new user.
2.8
9.
The user instructs the editor to replace all NIL's (in this case there is
only one) by 1.
The editor physically changes the expression
it is
operating on so when the user exits from the editor, his function,
as it
is now being interpreted. has been changed.
10. The user exits from the editor and returns to the break.
11. The user specifies the value to be used by itimes in place of NIL by using
the break command RETURN. This causes the computation to continue, and 6 is
ultimately returned as the value of'the original input, fact(3).
12. The user prettyprints (Section 14) fact,
i.e. asks it be printed with
appropriate indentations to indicate structure.
a comment facility.
Prettyprint also provides
Note that both tbe changes made to fact by the editor
and those made by DWIM are in evidence.
13. The user writes his function on a file by using prettydef (Section 14),
creating a TENEX file, FACT.;l, which when loaded into INTERLISP at a later
date via the function load (Section 14), will cause fact to be defined as
it currently is.
restoring
an
There is also a facility in INTERLISP for saving and
entire
core
image via
the
functions
Sysout
and
sysin
(Section 14).
14. The user logs out, returning control to TENEX.
However, he can still
continue his session by re-entering INTERLIBP via the TENEX REENTER or
CONTINUE command.
2.9
Index for Section 2
Page
Numbers
APPLY[FN;ARGS] SUBR
apply format
APPLY*[FN;ARG1; .•. ;ARGn] SUBR*
ARGlIST[X]
back trace
....................•••••.•••••••••••
................................... .
BAD ARGUMENT
FASSOC (error message)
BAD ARGUMENT
FLAST (error message)
BAD ARGUMENT
FLENGTH (error message)
BAD ARGUMENT
FMEHB (error message)
BAD ARGUMENT
FNTH (error Illessage)
BT (break command)
CONTINUE (tenex command)
CONTROL[U] SUBR
control characters
control-A
control-C
control-D
control-O
control-Q
control-U
debugging
OEFINE[X]
OEFINEQ[X] NL*
dot notation
DWIM
EQ[X;Y] SUBR
· ..................................... .
·..................................... .
·..................................... .
eQ
2.1
2.6
2.3
.................................... .
EQUAL[X;Y] ·
equal
escape character
EVAL[X] SUBR
eval format
EVALQT
FASSOC[X;Y]
files
FLAST[X]
FLENGTH[X]
FMEMB[X;Y]
FNTH[X:N]
function definition cell
functional arguments
garbage collection
GETD[X] SUBR
line-buffering
LINELENGTH[N] SUBR
LISTP[X] SUBR
lists
lOAO[FILE;LDFLG;PRINTFLG]
lOGOUT[] SUBR
NlISTP[X]
NOBINO
null-check
predicates
PRETTYDEF
PRETTYPRINT
PRINTlEVEl[N] SUBR
• • • • • '• • • • • • • •
I
••••••••••••••••••••••
.......... .......................... .
...........................................
'
........................................
·..................................... .
.......... ................... .
....................................
'
.......................
·..................................... .
·............................... ...... .
·.................................... .
·.................................... .
·..................................... .
.....................................
..............................
•••••••
II
•••••••••••••••••••••••••••
'
INI)EX.2.1
2.3-4
2.4
2.3
2.3
2.8
2.3
2.3
2.3
2.3
2.3
2.8
·2.4,9
2.5
2.4-5
2.4
2.4
2.4
2.4
2.4
2.5
2.8
2.6
2.6
2.3
2.3
2.3
2.6
2.4,6
2.4
2.4
2.3
2.9
2.3
2.3
2.3
2.3
2.3,6
2.3
2.4
2.3,6
2.5
2.3
2.3
2.3
2.9
2.4
2.2
2.3,8
2.2
2.3
2.9
2.9
2.3
Page
Numbers
prompt character
property list
pushdown list
PUTD[X;Y] SUBR
RADIX[N] SUBR
REENTER (tenex command)
RETURN (break command)
rubout
square brackets
SYSIN[FILE] SUBR
SYSOUT[FILE] EXPR
TENEX
true
(U V W) (value of ARGlIST)
U.B.A. (error message)
value cell
variable bindings
~ (carriage-return)
I I (typed by system)
X (escape characterl
notation
(typed by system)
\ (typed by system)
...................................
.........................
.................................
................................
......... ................................. .
"
••••
ill
......................
...............................
•••••••••••••••••••••••••••••••••
••••••••
0
••••• _
•••••••••••••
..............................
••••••••• 0
•••••••••••••••••••
]
~
(typed by system)
INDEX.2.2
2.4.6,8
2.3
2.8
2.3,6
2.3
2.4,9
2.9
2.5
2.5
2.9
2.9
2.4,6,9
2.2
2.3
2.8
2.3
2.8
2.5
2.4
2.6
2.1
2.8
2.4
2.5
2.4,6
SECTION 3
DATA TYPES, STORAGE ALLOCATION, AND GARBAGE COLLECTION1
INTERLISP operates ;in an 18-bitaddress spaci.
This address space is divided
into 512 word pages with a limit of 512 pages, or 262,144 words, but only that
portion of address space. currlntly in use actually exists on a·ny storage
medium.
INTERLISP itself· and>. all data storage are containld within this
address space. . A pointe... to a data Ile.entsuch as a nullber, atOll,·etc., is
simply thl addrlss of the data'll,.ent in this 18-bit'address spaci •
. 3.1
Data Types
The data types of INTERLISP are lists, atoms, pnames, arrays, large and small
integers,
floating
point numbers,
string .
~haracters
.and string pointers.
Compiled code and hash arrays are currently included with arrays.
In the descriptions of the various data types given below, for each data type,
first the input syntax and output format are described, that is, what. input
sequence will cause the INTERLISP read program to construct an Illment of that
type, and how the INTERLISP print program will print such an Ilemlnt.
those functions that construct aliments of that data type are given.
Next,
Note that
some data types cannot be input, thlY can only be constructed, e.g. arrays.
Finally, the format in which an Il ••lnt of that data type i·5 stor.d in •••ory
is described.
i---------------------------------------------------~-------------------------This section was written by A. K. Hartley.
3.1
3.1.1
Literal Atoms
A literal atom is input as any string of non-delimiting characters that cannot
be interpreted as a number.
The syntatic characters that delimit atoms are
space, end-of-line,2 line-feed, ,~ ( ) • ] and [.
However, these characters may
be included in atoms by precedin" them with the escape character X.
Literal atoms are printed by print and prinZ as a sequence of characters ,with
xes inserted before all delimitilllg characters (so that the atom will read back
in properly).
Literal atoms are printed by print asa sequence of characters
wi thout
extra X' s.
these
For example,
the atom consisting of
the
five
characters A, B, C, (, and 0 will be printed as ABCX(D by print and ABC(D by
prinl.
The extra Xt 5 are an art1lfact of the print program; they are not stored
in the atom's pname.
Li teral atoms can be constructed by pack, mkatom, and gensym (which uses.
mkatom) •
Literal atoms are unique.
In other words, if two literal atoms have the same
pname, i.e. print the same, they will allDalls be the same identical atom, that"
is, they will always have the same address in memory. or equivalently, they
will always be
corresponding to
!!l.a
~
Thus if ~lck or mkatom is given a list of characters
literal atom that already exists, they return a pointer to
that atom, and do not make a new atom.
Similarly, if the read program is given
as input of a sequence of char'acters for which an atom already exists. it
returns a pointer to that atom.
j--------------_________________
end-of-line character
carriage-return.
An
8
O ___________________
is
transmitted
by
~ _________________________
TENEX
when
it
sees
_
a
Note that this is not true for strings, large integers, floating point
numbers, and lists, i.e. the~, all can print the same without being g.
3.2
A literal atom is a 3 word (36 bits) datum containing:
PROPERTY LIS T
(CDR)
WORD I:
0
WORD 2:
TOP LEVEL BINDING
(CAR)
17
18
35
FUNCTION CALLING I NSTRUCTIO N
0
WORD 3:
PNAME
0
I
35
RESERVED FOR FUNCTIONS
ON FILES
17 18
35
I
FIGURE 3-1
Car of a literal atom, i.e. the right half of word 1, contains its top level
binding,
initially the atom NOBIND. Cdr of the atom is a poi'nter to, its
property list, initially NIL.
Word Z. the function definition cell. is a full 36 bit word, containing an
instruction to be executed for calling the function associated with that atom,
if any.
The left half differs for different function types (i.e., EXPR, SUBR,
or compiled code); the right half is a pointer to the function definition. 4
The pname cell, the left half of the third word, contains a pointer to the
pname of the atom.
The remaining half word is reserved for an extension of
INTERLISP to permit storing function definitions on tiles.
a-------------------------------------------------------~---------------------This use of a full word saves some time in function calls trom compiled
code in that we do not need to look up the type of the function definition
at call time.
3.3
3.1.2
Pnames
The pnames of atoms, 6 pointed to in the third word of the atom, comprise
another data type with storage assigned as it is needed.
occurs as a component of an atom or 'a string.
This data type only
It does not appear, for example,
as an element of a list.
Pnames have no input syntax or, output format as they cannot be directly
referenced by user programs.
A pname is a sequence of 7 bit characters packed 5 to a word, beginning at a
word boundary.
The first chara«:ter of a pname contains its length; thus the
maximum length of a pname is 126 characters.
3.1.3
Numerical Atoms
Numerical atoms. or simply numbBrs, do not have property lists, value cells,
functions definition cells. or e'xplicit pnames.
There are currently two types
of numbers in INTERLISP: integer:s, and floating pOint numbers_
Integers
The input syntax for an integel'" is an optional sign (+ or -) followed by a
6-~-----~-----------~--------------------------------- -------------------------
All INTERLISP pointers have pnames, since we define a pname Simply to be
how that pointer is printed. However, only literal atoms and strings have
their pnames explicitly st()red. Thus, the use of the term pname in a
discussion of data types 01" storage, allocation means pnames of atoms or
strings, and refers to a sequence of characters stored in a certain part of
INTERLISP's memory_
3.4
sequence of digits, followed by an optional Q.8 If the Q is present, the digits
are interpreted in octal, otherwise in decimal, e.g. 77Q and 63 both correspond
to the same integers, and in fact are indistinguishable internally since no
record is kept of how integers were created.
The setting of radix (Section 14), determines how integers are printed: signed
or unsigned, octal or decimal.
Integers are created by pack and mkatom when given a sequence of characters
observing the above syntax, e.g.
(PACK (LIST 1 2 (QUOTE Q») • 10.
Integers
are also created as a result of arithmetic operations, as described in Section
13.
An integer is stored in one 36 bit word: thus its magnitude must be less than
2t35. 7 To avoid h~ving to store (and hence garbage collect) the values of small
integers.
a few pages of address space, overlapping the INTERLISP machine
language code, are reserved for their representation.
ttself, minus a constant, is the value of the number.
'small' integers is -1536 thru +1535.
The small number pointe ..
Currently the range of
The predicate smallp is used to test
whether an integer is IsmaIl'.
While small integers have a unique representation, large integers do not.
In
other words, two large integers may have the same value. but not the same'
address in memory. and therefore not be!!.
For this reason the function
~
(or equal) should be used to test equality of large integers.
6---~-------~~-----------------------------------------------------------------
and terminated by a delimiting character.
self-delimiting, e.g. lists.
7
Note that
50..8
data types ar.
If the sequence of digits used to create the integer is too large, the high
order portion is discarded. (The handling of overflow as a result of
arithmetic operations is discussed in Section 13.)
3.5
Floating Point Numbers
A floating point number is input as a signed integer, followed by a decimal
point, followed by another sequence of digits called the fraction, followed by
an exponent (represented by E followed by a signed integer). B Both signs are
optional, and either the fraction following the decimal point, or the integer
preceding the decimal point may be omitted.
One or the other of the decimal
point or exponent may also be om:l.tted, but at least one of them must be present
to distinguish a floating poin1; number from an integer.
For example,
the
following will be recognized as floating point numbers:
5.
5.00
5.01.
.3
5E-3
-5.2E+6
5.1E2
5E2
Floating point numbers are pril1lted using the facilities provided by TENEX.
INTERLISP calls the floating point number to string conversion routines 9 using
the format control specified by the function fltfmt (Section 14);
initialized to T.
or free fOMllat.
For example,
fltfmt· is
the above floating point
numbers would be printed free format as:
5.0
5.0
5.01
.3
.0051
-5.2E6
500.0
510.0
Floating point numbers are also c:reated by pack and mkatom, and as a result of
arithmetic operations as described in section 13.
A floating point number is storedl in one 36 bit word in standard POP-tO format.
The range is ±2.94E-39 thru ±1.69E38 (or 2t-128 thru 2tI27).
8---~------------------------------------------------- -------------------------
and
9
terminate~
by a delimiter.
Addi tional information concerning these conversions may be obtained from
the TENEX JSYS Manual.
3.6
3.1.4
Lists
The input syntax for a list is • sequence perty listsobserue this conue~tion by cl/cling down the property lists two
cdrs at a time. Nost of these Junctions also generate an error. ARG NOT ATOM,
i! given an argument which is not a literal atom, i.e., thell cannot be used
directly on lists.
The term 'property name' or ' property' is used for the propertll indicators
appearing in the odd positions, and the term 'property ualue' or 'ualue oj a
property' or simply 'ualue' lor the ualues appearing in the euen positions.
Sometimes the phrase 'to store on the property --' is used, meaning to place
the indicated tnformation on the property list under the property name --.
Properties are usuallY atoms. although no checks are made to eliminate use oj
non-atoms in an odd position. However, the property list searching functions
all use g.
Property List Functions
put[atm;prop;val]
puts on the property list of atm, the property
~
with value val.
value for the property
val replaces any previous
~
on this property list.
Generates an error, ARG NOT ATOM, if atm is not a
literal atom.
addprop[atm,prop;new;flg]
~
Value is val.
the value n!! to the list which is the value
of property
~
on property list of atm.
If fIg
is T. !!!!! is consed onto the front of value of
7.1
~,
otherwise it is
~ed
on the end (nconct).
If atm does not have a property 2rQ2. the effect
is
the
same
as
put[atm;prop;list[new]],
for
exaunple, if addprop[FOO;PROP;FIE] is followed by
addprop[FOO;PROP;FUM],
be (FIE FUM).
getp[FOO;PROP]
will
The value of add prop is the (new)
property value.
If atm is not a literal atom,
generates an error, ARG NOT ATOM.
remprop[atm;prop]
removes all occurrences of the property 2r22 (and
its value) from the property list of atm.
is
~
is
not
Value
if any were found, oth,erwise NIL. If !!!!!
a
literal
atom,
generates
an
error,
ARG NOT ATOM.
changeprop[x;propl;prop2]
Changes
name
of
property
~
to
~
on
property list or !, (but does not arrect the value
or the property).
Value is !. unless
~
is not
round, in which case, the vaiue is NIL. If ! is
not
a
literal
atom,
generates
an
error,
Gets th. item arter the atom l on list!.
If l is
ARG NOT ATOM.
get[x;y]
not on the list !, value is NIL. For example,
get[A B C D):B].C.
Note, since i!! terminates on a non-list, get[atom,anuthing] is NIL.
Thererore, to search a property 1is t, Il!!I!. shou ld
be used, or get applied to cdr(atom].
7.2
getp[atm;prop]
gets the property value for
list of!!m.
~
from the property
The value of S!12 is NIL if atm is
not a literal atom, or irQ2 if not found.
Note, the ualue of 2!!! mau al80 be NIL, iJ there i8 an
the corre8ponding propertu ualue i8 NIL.
Note: Since
time,
~
~ccurrence
oj
~
but
searches a list two items at a
the same object can be used as
both
a
property name and a property value, e.g., if the
property list of atm is (PROP1 A PROP2 B A C),
then
getp[atmjA] • C.
Note
that
however
get[cdr[atm];A] • PROP2.
getlis[x;props]
searches the property list of !. and returns the
property list as of the first property on props
that it finds e.g., if the property list of ! is
(PROP1 A PROP3 B A C),
getlis[xj(PROPZ PROP3)]=(PROP3 B A C)
Value is NIL if no element on
~
is found.
!
can also be a list itself, in which case it is
searched as above.
deflist[l;prop]
is used to put values under the same property name
on the property lists of several atoms.
list of two-element lists.
! is a
The first element of
each is a literal atom, and the second element is
the property value for the property
~.
The
value of deflist is NIL.
Note,
Manu atom8 in the8U8tem fllreadu haue propertu li8t8, with properties
used bU the compiler. the brealtpacltalle. DWIH, etc.
Be careful not to
clobber such sU8tem propertie8. The ualue oj 8U8'prop8 gilles the complete
li8t of the propertu names used bU the 8ustem.
7.3
7.2
Hash Links
The description of the hash link facility in INTERLISP is included in the
chapter on property lists because of the similarities in the ways the two
features are used.
A property list provides a way of associating information
with a particular atom.
pointe~
A hash link is an association between any INTERLISP
(atoms, numbers, arrays
II
strings, lists, et al) called the hash-item,
and any other INTERLISP pointer called the hash-value.
stored in cdr of the atom.
called the hash-address,
Property lists are
Hash links are implemented by computing an address,
in a specified array. called the hash-array,
and
storing the hash-value and the hash-item into the cell with that address.
The
contents of that cell, i.e. the hash-value and hash-item, is then called the
hash-link. 1
Since the hash-array is obviously much smaller than the total number of
. possible hash-items,2 the hash-address computed from item may already contain a
hash-link. If this link is fro[[l item, 3 the new hash-value simply replaces the
old' hash-value.
be computed,
Otherwise, ano1;her hash-address (in the same hash-array) must
etc. until an empty cell is found, 4 or a cell containing a
hash-link from item.
When a hash link for item is being retrieved, the hash-address is computed
i--~-~--~~~--~--~-~-~-----------'------·----~--------- ----------------------~-~-
The term hash link (unhyphenated) refers to the process of associating
information this way. or thEI 'association' as an abstract concept.
2
3
4
which 1s the total number of INTERLISP pointers, i.e., 256K.
~
is used for comparing
itE~
with the hash-item in the cell.
After a certain number of iterations (the exact algorithm is complicated),
the hash-array is considered to be full, and the array is either enlarged,
or an error is generated, as described below in the discussion of overflow.
7.4
using the same algorithm as that employed for making the hash link.
corresponding cell is empty, there is no hash link for item.
hash-link
from
item,
the
hash-value
is
hash-address must be computed, and so forth. 6
returned.
If the
If it contains a
Otherwise,
another
Note that more than one hash link can be associated with a given hash-item by
using more than one hash-array.
Hash Link Functions
In the description of the functions below, the argument array has one of three
forms:
(1)
NIL,
in
which
case
the
hash-array
provided
by
the
system,
syshasharray. is used;6 (2) a hash-array created by the function harray, or
created 'from an ordinary array using clrhash as described below; or (3) a list
~
of which is a hash-array.
The latter form is used for specifying what is
to be done on overflow, as described below.
harray[n]
creates a hash-array of size n,.
equivalent to
clrhash[array[n]].
clrhash[array]
sets all elements of array to 0 and sets left half
of first word of header to -1.
puthash[item;val;array]
Value is array.
puts into array a hash-link from item to val.
6--~---------------------------------------------------------------------------
For reasonable operation, the hash array should be ten to twenty percent
larger than the maximum number of hash links to be made to it.
6
syshasharray is not used by the system, it is provided solely for the
user's benefit.
It is initially 512 words large, and is automatically
enlarged by 50" whenever it is 'full'. See page 7.7.
7.5
Replaces previous link from same item, if any.
val=NIL
any
old
link
is
removed,
hash-value or NIL is not allowed).
gethash[item;array]
If
(hence
Value is
a
~.
finds hash-link from item in array. and returns
the hash-value.
Value is NIL if no link exists.
gethash compiles open.
rehash[oldar:newar]
hashes all items and. values in oldar into newar.
The two arrays do not. have to be (and usually
aren't) the same size.
maphash[array:maphfn]
Value is
~.
maphfn is a function of two arguments.
For each
hash-link in array, maphfn will be applied to the
has,h-value
and
hash-item,
e.g.
maphash[a;(LAHBDA(X Y) (AND(LISTP Y) (PRINT X»)]
will print the hash-value for
1is,ts.
dmphash[arrayname]
al~
hash-links from
The value of maphash is array.
Nla~da-nospread
that prints on the primary output
file a loadable form which will restore what is in
thEI
(E
hash-array
specified
(DHPHASH SYSHASHARRAY»
by
arrayname,
e. g.
as a prettydef command
will dump the system hash-array.
Note, all g identitie~ except G/tom~ and ~mall integer~ are Lost bU dumping and
l oading becau~e read wi II create new ~tructure for each item.
Thus if
two li~t~ contaiRan !!l. substructure, when theu are dumped and Loa~ed
baclc. in. the corre~pondinQ' ~ub~tructure~ while equal are no Longer g.
7~-~---------------------------·'-----------------------------------~----------circlprint and circlmaker (Section 21) provide a way of dumping and
reloading structures contaill'ling !!l substructures so that these identities
are preserved.
7.6
Hash Overflow
By using an array argument of a special form.
the user can
provide
for
automatic enlargement of a hash-array when it overflows, i.e., is full and an
attempt is made to store a hash link into it.
the
form (hash-array. n),
rr
f
a
In the first case. a new hash-array
is
II a PQsitive integer;
floating point number; or (hash-array)
created with
The array argument is either of
0
or (hash-array. f),
more cells than the current hash-array.
In the second case, the
new hash array will be f times the size of the current hash-array.
case, (hash-array), is equivalent to (hash-array. 1.5).
The third
In each case, the old
hash-array is rplacaed into the dotted pair, and the computation continues.
If . a hash-array overflows, and the array argument used was not one of these
three forms, the error HASH TABLE FULL is generated, which will either cause a
break or unwind to the last errorset. as per treatment of errors described in
Section 16.
The system hash array. syshasharray, is automatically enlarged by 1.5 when it
is full.
7.7
Index for Section 7
Page
Numbers
.......................
AOOPROP[ATH;PROP;NEW;FlG]
ARG NOT ATOM (error message)
CHANGEPROP[X;PROP1;PROP2]
CIRClMAKER[L]
CIRCLPRINT[L;PRINTFLG;RLKNT]
CLRHASH[ARRAY] SUBR
OEFtIST[L;PROP]
OMPHASH[L] NLtfr
ERRORSET[U;V] SUBR
GET[X;Y]
GETHASH[ITEM;ARRAY] SUBR
GETLIS[X;PROPS]
GETP[ATM;PROP]
HARRAY[lEN]
hash link functions
hash links ·
hash overflow
HASH TABLE FULL (error message)
hash-address
hash-array ·
hash-item
hash-link
hash-value
MAPHASH[ARRAY;HAPHFN]
property
property list
• •••••••••••••• '* •••••••••••••••••
property name
'property value
PUT[ATH;PROP;VAL]
PUTHASH[ITEH;VAL;ARRAY] SUBR
REHASIf[OLOAR;NEWAR] SUBR
REMPROP[ATH;PROP]
SYSHASHARRAY (system variable/parameter)
SYSPROPS (system variable/parameter)
value of a property
·................... ............ .
.................................... .
.....................................
....................................
.......................................
·.................................... .
·............................... .
...............................
............
......... .................. .
~
INDEX.7.1
7.1
7.1-2
7.2
7.6
7.6
7.5
7.3
7.6
7.7
7.2
7.6
7.3
7.3
7.5
7.5-6
7.4-6
7.7
7.7
7.4
7.4-5,7
7.4-6
7.4-6
7.4-6
7.6
7.1
7.1-3
7.1,3
7.1,3
7.1-2
7.5
7.6
7.2
7.5,7
7.3
7.1
SECTION 8
FUNCTION DEFINITION AND EVALUATION
General Comments
A function defini tion in INTERLISP is stored in a special cell called the
function definition cell, which is associated with each literal atom.
This
cell is directly accessible via the two functions putd, which puts a gefinition
in the cell, and getd which gets the
the funct;i.on
~
from the cell.
In addition,
returns the function type, i.e., EXPR, EXPR*
FSUBR* as
described in Section 4.
an
expr,
compiled
~.finition
and subrp, are true if the function is
~,ccodep,
function,
or
subr
respectively;
argtype
returns
0, 1, 2, or 3, depending on whether the function is a spread or nospread (i.e.,
its fntyp ends in *), or evaluate or no-evaluate (i.e., its
~
begins with F
or CF); arglist returns the list of arguments; and nargs returns the number of
arguments.
~,exprp,
ccodep, subrp. argtype, arglist, and nargs can be
given either a literal atom, in which case they obtain the function definition
from the atom's definition cell, or a function definition itself.
Subrs
Because subrs,l are called in a special way, their definitions are stored
i-----------------------------------------------------------------------------Basic functions, handcoded in machine language, e.g. cons, car, cond. The
terms subr includes spread/nospread, Ival/noeval functions,-r7e.~e four
(ntype s SUBR, FSUBR, SUBR·, and FSUBR ••
8.1
differently than those of compiled or interpreted functions.
In the right half
of the definition cell is the address of the first instruction of the subr. and
in the left half its argtype: 0, I, 2, or 3.
pair of argtype and
addr~ss.
the definition cell. but a new
getd of a subr returns a dotted
Note that this is not the same word as appears in
~ffi!;
i.e •• each getd of a subr performs a £Qn!.
Similarly. putd of a definition 'of the form (number. address). where number
=
0, 1, 2, or 3, and address is in the appropriate range, stores the definition
as a subr, i. e., takes the £.2!l!. apart and stores £!!: in the left half of the
defini tion cell and cdr in the rJLght half.
Validity of Definitions
Al though the function definition c'ell is intended for function definitions,
putd and getd do not make thorough checks on the validity of definitions that
"look like" exprs, compiled code, or subrs.
Thus if putd is given an array
pointer, it treats it as compiled code, and Simply stores,the array pOinter in
the definition cell.
getd will then return the array pointer.
Similarly. a
call to that function will simply transfer to what would normally be the entry
\
point for the function, and plroduce random results if the array were not
compiled function.
Similarly. if putd is given a dCltted pair of the form (number
0
address) where
number is O. 1, 2, or 3, and address falls in the subr range. putd assumes it
is a subr and stores it away as described earlier.
getd would then return £2.!l!
of the left and right half, i.e 0, a dotted pair equal (but not!.9.) to the
expression originally given put!!.
Similarly, a call to this function would
transfer to the corresponding address.
Finally, if putd is given any other list, it simply stores it away.
this
A call to
function would then go through the interpreter as described in the
appendix.
8.2
Note that putd does not actually check to see if the s-expression is valid
defin it ion. i. e., begins with LAMBDA or NlAMBDA. Simi larly. m.r.J! is true if a
definition
is
a
list
and
not of
the
form
(number. address),
number
=
0, 1, 2, or 3 and address a subr address; subrp is true if it is of this form.
arglist and nargs work correspondingly.
Only fntyp and argtype check function definitions further than that described
above: both argtype and
~
return NIL when
~
is true but £!!: of the
definition is not LAMBDA or NLAMBDA.2 In other words, if the user uses putd to
put (A Be) in a function definition cell. getd will return this value, the
editor and prettyprint will both treat it as a definition, exprp will return T.
ccodep and subrp NIL, arglist B, and nargs 1.
getd[x]
gets the function gefinition
of~.
Value 1s the
definition. 3 Value is NIL if ~ is not a literal
atom, or 'has no definition.
fgetd[x]
fast
version
of
getd
car[vag[addl[loc[x]]]].
that
compiles
open
as
Interpreted. generates an
error, BAD ARGUMENT - FGETD, if .! is not a literal
atom. 4
2---~~;;;-;~~~~~~~;-~;~;-d~~~;;;~~-~;i~;-~~-~;~;~;;-;~d-~~~~~O;;-;~d-~;~~;-~~;;
check.
The compiler and interpreter also take different actions for
LAMBDAs and NlAMBDAs, and therefore generate errors if the definition is
neither.
8
Note that getd of a subr performs a
footnote on fgetd below.
4
Fgetd is intended primarily to check whether a function ha~ a definition,
rather than to obtain the definition. Therefore, for subrs, fgetd returns
just the address of the function definition, not the dotted pair returned
by get~, page 8.2, thereby saving the cons.
8.3
£Q!!!,
as described on page 8.2.
See
putd[x;y]
put:s the !!efinition
Value
into !'S function cell.
Generates an error, ILLEGAL ARG -
is~.
PUTD, if !
~
is not a literal atom, or 'J. is a
string. number. or literal atom other than NIL.
putdq[x;y]
nlalmbda
version
of
considered quoted.
movd[from.to;copyflg]
Moves
the
redefines
putd;
If
arguments
are
Value is !.
definition
to.
both
of
from
copyflg=T,
definition of from is used.
meaningful forexprs,
to
a
!2,
£22'i.
i.e.,
of
the
copyflg=T is only
although movd works
compiled functions and subrs as well.
for
The value
of .movd is to.
Note,
subrp. ccodep. exprp. aratupe. nargs. and argltst all can be gtuen
etther the name 0/ a function. or a deftnttton.
~.
fntyp[fn]
Value is NIL if fn is not a function definition or
the name of a defined function.
Otherwise fnt'J.P
returns one of the following as defined 1n the
section on function types:
EXPR
CEXPR
SUBR
FEXPR
CFEXPR
.FSUBR
EXPR*
CEXPR*
SUBR*
FEXPR*
CFEXPR*
FSUBR*
The prefix
r
indicates unevaluated arguments, the
prefix £ indicates compiled code; and the suffix •
indicates an indefinite number of arguments.
8.4
~
returns FUNARG if fn is a funarg expression.
See Section 11.
subrp[fn]
is true if
an~
only if fntyp[fn] is either SUBR,
FSUBR, ·SUBR". ,or FSUBR-, i. e.. the third column of
fntyp's.
ccodep[fn]
is true if and only if fntyp[fn] is either CEXPR,
CFEXPR, CEXPRft,or CFEXPR*, i.e., second column of
fntyp's.
exprp[fn]
is true if fntyp[fn] is either EXPR, FEXPR, EXPR*,
or
FEXPR*,
i.e. ,
first
column
of
fntyp' s.
However, exprp[ fn] is also true if fn is (has) a
list definition that is not a SUBR, but does not
begin with either LAMBDA or NLAMBDA.
In other
words" exprp is not quite as selective as fntyp.
argtype[fn]
fn is the name of a function or its definition.
The value of argtype is the argtype of fn, i.e.,
0, 1 p 2, or 3, or NIL if fn is not a function.
The interpretation of the argtype is:,
o
eval/spread function
(EXPR, CEXPR, SUBR)
1
no-eval/spread functions
(FEXPR, CFEXPR, FSUBR)
2
eval/nospread functions
(EXPR*, CEXPR*, SUBR*)
3
no-eval/nospread functions
(FEXPR*, CFEXPR*, FSUBR*)
i.e.,
argtyp~
8.5
corresponds to the roUls of fntyps.
value is the number of arguments of fn, or NIL if
fn is not a function. 6 nargs uses exprp, not
nargs[fn]
fnty~,
so that nargs[(A (B C) 0)]-2. Note that if
fn 1s a SUBR or FSUBR, nargs • 3, regardless of
the number of arguments logically needed/used by
If
the routine.
nars,s
arglist[fn]
fn
is a nospread
= 1.
,value is the 'argument list' for fn.
the
function,
'argument
functions.
list'
is
an
atom for
Note that
nospread
Since NIL is a possible value, for
arglist,
generated",
ARG:S NOT AVAILABLE, if fn is not a function. 6
If fn is a
FSUBR-,
SUBR·
or
FSUBR,
the value is U.
an
error
the value of arglist is
is
(U
V W), if a
SUBR-
or
This is merely a •feature , of arglist, subrs do not
actually store the names U, V, or W on the stack.
However. if the user breaks
or traces a SUBR (Section 15), these will be the argumen't names used when an
equivalent EXPR definition is constructed.
define[x]
The argument of define is a list.
Each element of
the list is itself a list either of the form (name'
definition)
or
(name
arguments
••• ).
In
the
second case, following 'arguments' Is the body of
the definition.
As an
example,
consider
the
6-------------~------------------------------------------------------~--------1.e., if ~, ccodep, and subrp are all NIL.
6
If fn is a compiled function, the argument list is constructed, 1.e. each
call to arglist requires making a new list. for interpreted functions, the
argument list is simply cadr of getd.
8.6
following two' equivalent expressions for defining
the function null.
1)
(NULL (LAMBDA (X) (EQ X NIL»)
2)
(NULL (X) (EQ X NIL»
define will generate an error on encountering an atom where a defining list is
expected.
If dfnflg=NIL. an attempt to redefine a function fn will cause
define to print the message (fn REDEFINED) and to save the old definition of fn
using savedef before redefining it.
redefined.
If dfnflg=T.
If dfnflg=PROP or ALLPROP, the
the function
is Simply
definition is stored on the
n~w
property list under the property EXPR. (ALLPROP affects the operation of rpaqq
and
~.
section 5).
dfnflg is initially NIL.
dfnflg is reset by load to enable various ways of handling the defining of
functions and setting of variables when loading a file.
For most applications,
the user will not reset dfnflg directly himself.
Note,
define will operate correctlu if the Junction is alreadu deJined and
broken. aduised. or broken-in.
nlambda nospread version of define. i.e., takes an
indefinite
number
of arguments
evaluated.
Each Xi must be a list, of the form
described in define.
which
are
not
defineg calls define,
so
dfnfig affects its operation the same as define.
savedef[fn]
Saves the definition of tn on its property list
under property EXPR, CODE, or SUBR depending on
its!n!l2.
Value is the property name used.
If
getd[fn] is non-NIL, but fntyp[fn] is NIL, saves
on property name LIST. This situation can arise
8,.7
when a function is redefined which was originally'
defined with LAMBDA misspelled or omitted.
If l:n- is a list, savedef operates on each function
in
the list,
and
its value
is a
list
of
the
individual values.
unsavedef[fn;prop]
Res1~ores
lis1~
the definition of fn from' its property
under
Value is
~
property
~.
(see
savedef
above).
If nothing saved under J!.!:.Qj!. and
fn jls defined, returns (prop NOT FOUND
r,
otherwise
genorates an error, NOT A FUNCTION.
If
,~
is not given, i.e. NIL, unsavedef looks
undor EXPR, CODE, and SUBR, in that order.
value of unsavedef is the property name,
The
or if
nothing is found and fn is a function, the value
is (NOTHING FOUND);
otherwise generates an error,
NOT A FUNCTION.
If ,dfnflg=NIL, the current definition of fn.
any.,
is saved using savedef.
if
Thus one can use
I
unsilvedef to switch back and forth
between
two
defj,ni tions of the same function, keeping one on
its property list and the other in the function
deftnition cell.
If
fn
is
a
list,
unsavedef
operates
on
each
func:tion of the list, and its value is a list of
the individual values.
8.8
eval[x]7
eval evaluates the expression
~
and returns this
va lue i . e. eva 1 provides a way of call ing the
interpreter.
type
Note that eval is itself a lambda
function,
its
so
argument
is
the
first
evaluated, e.g.,
(ADD1 3»
(ADD1 3)
... (EVAL FOO)
~SET(FOO
4
"'EVAL(FOO)
(ADD1 3)
e[x]
nlambda
or
(EVAL (QUOTE FOO»
nospread
version
of
Thus
eval.
it
eliminates the extra pair of parentheses for the
list
apply[fn;args]
of
arguments
for
eval.
i.e.,
eval[x].
Note
however
equivalent
to
INTERLISP,
the user can type just !
evaluated.
(See Section 3.)
e
x
is
that
in
to get !
~
applies the function fn to the arguments
aras.
The individual elements of args are not
evaluated by
fn is simply called with args
as its argument list. 8 Thus for the purposes of
~,
~,
nlambda's and lambda's are
same.
However
like
eval,
~
treated
is
a
the
lambda
function so its arguments are evaluated before it
is called e.g.,
7-----------------------------------------------------------------------------eval is a 5ubr 50 that the 'name' ! does not actually appear on the stack.
8
Note that fn
itself, as in
(APPLY (QUOTE
(APPLY (QUOTE
(ADD1 3). .
may still explicitly evaluate one or more of its arguments
the case of setq. Thus
SETQ) (QUOTE (FOO (ADD1 3»» will set FOO to 4, whereas
SET) (QUOTE (FOO (ADD1 3»» will set FOO to the expression
8.9
..SET(FOOI 3)
3
..SET(FOOl 4)
4
.. (APPLY (QUOTE IPLUS) (LIST FOOl FOOl]
7
Here, fool and fo02 were evaluated when the second
~
argument to
was evaluated.
Compare with:
..SET(FOOl (ADDl Z»
(ADDl 2)
..SET(FOOl (SUB1 5»
(SUBl 5)
.. (APPLY (QUOTE IPLUS) (LIST FOOl FOOZ]
NON-NUMERIC ARG
(AD01 Z)
equi.valent to
example,
if
apply[fnjlist[arg ; ••• ;arg n ]] For
1
fn is the name of a functional
argument to be applied to ! and
(APPLY* FN X Y),
which
(APPLY FN (LIST X Y».
is
Note
X. one can write
equivalent
that
to
(FN X Y)
spe(:ifies a call to the function FN itself. and
will cause an error if FN is not defined.
Sec1~ion
evala[x;a]
(See
FN will not be evaluated.
16.)
Simulates a-list evaluation as in LISP 1.5.
~
is a
forl1la, ! is a list of dotted pairs of variable name
! is 'spread' on the stack, and then
and value.
~
is evaluated, i.e. t any variables appearing free
in
~~,
will
~hat
be
also appears as
given
the
value
E![
in
of an element of .!
the
cdr
of
that
elelllent.
rpt[rptnjrptf]
Evaluates the expression rptf rptntimes.
At any
POillt. rptn is the number of evaluations yet to
8.10
take
place.
evaluation.
Returns
If rptn
~
the
value
of
the
last
0, rptf is not evaluated,
and the value of rpt is NIL.
Note, !21 is a lambda function. so both its arguments are eualuated be/ore ~
is called. For most applications. the user will probablu lDant to use
!P.!:.!I. •
rptq[rptn;rptf]
nlambda version of rpt:' rptn is evaluated, rptf is
not, e.g. (RPTQ 10 (READ»
to read.
arg[var;m]
~
will perform ten calls
compiles open.
Used to access the individual arguments
lambda nospread function.
arg
function used like .!!!
is the name of' the
atomic
argument
list
y!.!:
to
a
function, and is not evaluated;
and
example,
following
the
is
an
nlambda
lambda-nospread
mis
the desired argument,
consider
is
of a
the number of
evaluated.
definition
For
of
iplus in terms of plus.
[LAMBDA X
(PROG «M 0)
LP
(N 0»
(COND
«EQ N X)
(RETURN H»)
(SETQ N (ADOl N»
[SETQ M (PLUS M (ARG X N»)
(GO LP]
The value of arg is undefined for
mless
than or
equal to 0 or greater than the ualue of y!!:. 9
Lower numbered arguments appear earlier in the
form, e.g. for (IPLUS A B C),
8.11
arg[X;l]=the value of A,
arg[Xi2]cthe value of B, and
arg[X;3]=the value of C.
Note that the lambda variable should never be
reset.
However, individual arguments can be reset
using setarg described below.
setarg[var;m;x]
set~
to
~
the mth argument for the lambda nospread
fun'ction whose argument
considered quoted,
mand!
list
is Y.ill:.
Y1!.!:
is
are evaluated; e.g. in
the previous example, (SETARG X (ADD1 N)(HINUS H»
would be an example of the
set,arg.
8.12
correct
form
for
Index for Section 8
Page
Numbers
........................
a-list
ADVISED (property name)
ALLpROP
APPLY[FN;ARGS] SUBR
APPLY-[FN;ARG1; ... ;ARGn] SUBRARG[VAR;M] fSUBR
ARGLIST[X]
·
ARGS NOT AVAILABLE (error message)
ARGTYPE[FN] SUBR
argument list ·
BAD ARGUMENT - FGETD (error message)
BROKEN (property name) ·
BROKEN-IN (property name)
CCODEP[FN] SUBR ·
CEXPR (function type)
CEXPR* (function type)
CFEXPR (function type)
CFEXPR- (function type)
CODE (property name) ·
.........................................
............................... .
................................
................................. .
•
II
••••••••••••••••••••••••••••••
............
........................ .
........................
...............................
··.........................
..
........................
·........................ .
..........................
...........................
DE FIN E[ X] •••••••• '•••••••••••••••••••••••••••••••
DEFINEQ[X] NL*
OFNFLG (system variable/parameter) ..............
E[XEEEE] NL*
·................................ .
•
•••••
II
•••••••••••••••••••••••••••
................................ .
EVAL[X] SUBR
·
EVALA[X;A] SUBR
EXPR (property name)
EXPR (function type)
EXPR* (function type) ·
EXPRP[FN] SUBR
FEXPR (function type)
FEXPR- (function type)
FGETD[X]
FNTYP[ X]
FSUBR (function type)
FSUBR- (function type) ·
FUNARG (function type)
function definition and .evaluation
function definition cell
functional argument ·
GETD[X] SUBR
ILLEGAL ARG - PUTD (~rror message)
INCORRECT DEFINING FORM (error message)
interpreter
LAMBDA
LIST (property name)
MOVD[FROM;TO;COPYFLG]
NARGS[X]
NLAMBDA
nospread
NOT A FUNCTION (error message)
(NOT FOUNO)
(NOTHING FOUND)
PROP[X;Y]
PUTD[X;Y] SUBR
PUTDQ[X;Y] NL ·
REDEFINED (typed by system)
··..........................
.
.....................
....
.
......................... .
·................................ .
"
........................................
·......................... .
........................ .
............. "
............................. .
·........................... .
.....................................
......................................
........................................
•
...................
0
•••••••••
...................
··...............................
...................... ........ .
·................................. .
·................................ .
................................. .
.....................
INDEX.8.1
"
8.10
8.7
8.7
8.9
8.10
8.11
8.1,3-4,6
8.6
8.1-5
8.1
8.3
8.7
8.7
8.1,3-5
8.4-5
8.4-5
8.4-5
8.4-5
8.7-8
8.6-7
8.7
8.7-8
8.9
8.9
8.10
8.7-8
8.4-6
8.4-5
8.1,3-6
8.4-5
8.4-5
8.3
8.1,3-7
8.4-6
8.4-6
8.5
8.1-12
8.1-2
8.10
8.1-3,7
8.4
8.7
8.9
8.3,5,8
8.7
8.4
8.1,3-4,6
8.3,5
8.1
8.8
8.8
8.8
8.7
8.1-4
8.4
8.7
Page
Numbers
RPT[RPTN;RPTF]
RPTQ[RPTN;RPTF] NL
SAVEDEF[X]
"
SETARG[VAR;H~X] fSUBR
spread
SURR (function type)
SUBR (property name)
SUBR* (function type)
5UBRP[FN] SUBR
subrs
U (value of ARGLIST)
(U V W) (value of ARGLIST)
UNSAVEOEF[X;TYP]
... ......... ............. .
.... ...................... .
~
'
•• "
• • • • • • • 4t • • • • • • • • • • • • • • •
UIDEX.8.Z
8.10-11
8.11
8.7-8
8.12
8.1
8.4-6
8.7-8
8.4-6
8.1,3-5
8.1
8.6
8.6
8.8
SECTION 9
THE INTERLISP EDITOR t
The INTERLISP editor allows rapid, convenient modification of list structures.
"ost often it is used to edit function definitions, (often while the function
itself is running) via the function editf, e.g., EDITF(FOO). However, the
editor can also be used to edit the value of a variable, via !!!!!y, to edit a
property list, via editp, or to edit an arbitrary expression,
via~.
It is
an important feature which allows good on-line interaction in the INTERLISP
system.
This chapter begins with a lengthy introduction intended for the new user.
The
reference portion begins on page 9.15.
9~1
Introduction
Let us introduce some of the basic,editor commands, and give a flavor for the
edi tor's
language structure by guiding the reader through a hypothetical
editing session.
Suppose we are editing the following incorrect definition of
append:
i-----~---------·------------------------·------------ -----------.-.-----.-.----
The editor was written by and is the responsibility of W. Teitelman.
0.1
(LAMBDA (X)
Y
(COND
«NUL X)
Z)
(T (CONS (CAR]I
(APPEND (CDR X Y]
We call the editor via the funct;ion edi tf:
"EDITF(APPEND)
EDIT
*
The editor responds by typing EOIT followed bY., which is the editor's prompt
character, i.e., it signifies that the editor is ready to accept commands. 2
At any given moment, the editor's attention is centered on some substructure of
the
expression
being edited.
This substructure
is called
the
current
expre$$ion, and it is what the user sees when he gives the editor the command
P, for print.
Initially, the c:urrent expression ·is the top level one, i.e.,
the entire expression being edi t,ed.
Thus:
.p
(LAMBDA (X) Y (COND & &»
*
Note that the editor prints tho current expression as though pr1ntlevel were
set to 2, i.e., sublists of Slliblists are printed as &.
The command ? will
print the current expression as though printlevel were 1000.
*7
(LAMBDA (X) Y (COND «NUL X) Z) (T (CONS (CAR) (APPEND (COR X V»~»~»~
*
and the command PP will prettyprint the current expression.
2-------------------~-------------~----------------------------------------~~--
In other words. all lines beginning with • were typed by the user, the rest
the editor.
by
9.2
A positive integer is interpre,ted by the editor as a cODlDand to descend into
the correspondingly numbered element of the current expression. Thus:
*2
*p
(X)
*
A negative integer has a similar effect, but counting begins from the end of
the current expression and proceeds backward, i.e •• -1 refers to the last
element in the current expression, -2 the next to the last, etc.
For either
positive integer or negative integer, if there 1s no such element, an error
occurs,3 the editor types the faulty cODlDand followed by a 1, and then another
*
The current expre&&ion i& neller changed when a co.and cau&e.s fin error.
Thus:
*p
(X)
*2
2
1
*1
*p
X
•
A phrase of the form 'the current expression is changed' or 'the current
expression becomes' refers to a shift in the editor's attention, not to a
modification of the structure being edited.
When the user changes the current expression by descending into 'it, the old
current expression is not lost.
Instead, the editor actually operates by
a~~-----~----------------------------~---------------- -------------------------
'Editor errors' are not of the flavor described in Section 16. i.e., they
never cause breaks or even go through the error machinery but are direct
calls to error! indicating that a coaunand is in some way faulty. What
happens next depends on the context in which the command was being
executed.
For example, there are conditional commands which branch on
errors. In most situations, though, an error will cause the editor to type
the faul ty command followed by a 1 and wait for more input. Note that
typing control-E while a cOllUDand is being executed aborts the cOlIIDand
exactly as though it had caused an error.
9.3
maintaining a chain of expressions leading to the current one.
expression is simply the last link in the chain.
The current
Descending adds the indicated
subexpression onto the end of the chain, thereby making it be the current
expression.
The command 0 is used to ascend the chain; it removes the last
link of the chain. thereby making the preutou8 link be the current expression.
Thus:
-p
X
-0 P
(X)
-0
-1
P
(CONO (& Z) (T &»)
-
Note the use of several
conunand~»
on a single line in the previous output.
editor operates in a line buffered mode, the same as evalqt.
The
Thus no command
is actually seen by the editor', or executed, until the line is terminated,
either by a carriage return, or a matching right parenthesis.
The user can
thus use control-A and control-'l! for line-editing edit comands. the same as he
does for inputs to evalqt.
In our edi ting session, we will make the following corrections to append:
delete Y from where it appears, add Y to the end of the argument list,4 change
NUL to NUll, change Z to Y, add Z after CAR, and insert a right parenthesis
following CDR X.
first we will delete Y. By now we have forgotten where we are in the function
defini"tion, but we want to be at the ·top· so we use the cormnand· t, which
ascends through the entire chain of expressions to the top level expression,
4---T~;~;-~~~-~;;;;~~~~~-~~~id-~;-~~~~~h-~f-;;-~~;-~;;;;~~~~:-~:;::-HOV~-Y-f;~~
its current position to a ne'w position, and 1n fact there is a MOVE command
in the edi tor. However, f(Jr the purposes of this introduction, we will
confine ourselves to the simpler edit commands.
9.4
which then becomes the current expression, i.8., t re.ov•• all links except the
first one.
P
(LAMBDA (X) Y (COHO 6 6»
*t
*
Note that if we are already at the toP. t has no .ffect, i ••.• it is • NOP •
. However, 0 would generate an error.
In other words. t •••ns -go to the top,-
while 0 means wascend one link.-
The basic structure modification commands in the editor are:
n
(n)
~
1 deletes the corresponding
element from the current expression.
(n 8 1 •••
n ,m
em)
~
1 replaces the nth ele.ant in the current
expression with
(~n 8
1
••• 8
m)
n ,m
1 insertse 1 ••• e. before the nth element
in the current expression.
~
Thus:
*p
(LAMBDA (X) Y (COHO 6 6»
*(3)
*(2 (X
*p
V»~
(LAMBDA (X Y) (COHO 6 6»
*
All structure modification done bU the editor i, de,tructiue. t.e .• the editor
uses rplaca and rplacd to phustcaLLu chaR,e the ,tructure it .a, ,tuen.
Nota that all three of the above co..ands perfoMD their operation with respect
9.5
to the nth element from the front of the current expressioni the sign of ! is
used to specify whether the operation is replacement or insertion.
Thus. there
is no way to specify deletion or' replacement of the nth element from the end of
the current expression, or insertion before the nth element from the end
without counting .out that elelmant's position from the front of the list.
Similarly. because we cannot specify insertion after a particular element, we
cannot attach something at the end of the current expression using the above
commands.
Instead, we use thEI command N (for !!£2!!£).
Thus we could have
performed the above changes instead by:
*p
(LAMBDA (X) Y (COND 6 6»
lIr(3)
lIrZ (N Y)
*p
(X Y)
lIrt P
lIr (LAMBDA (X Y)
(CCJND & &»
*
Now we are ready to change NUL to NULL. Rather than specify the sequence of
descent commands necessary to re!ach NUL, and then replace it with NUll, e.g., 3
Z 1 (1 NULL), we will use F. the! find cODlDand, to find NUL:
*p
(LAMBDA (X Y) (COHD 6 6»
*F NUL
*p
(NUL X)
*(1 NULL)
*0 p
« NULL X) Z)
*
Note that F is special in that it corresponds to two inputs.
In other words, F
says to the edt tor, "treat your' next conunand as an expression to be searched
for." The search is carried out in printout order in the current expression.
If the target expression is not found there, F automatically ascends and
searches those portions of the higher expressions that would appear after (in a
printout) the current expression.
If the search is successful, the new current
9.6
expression will be the structure where the expressi,on was found, 6 and the chain
will be the same as one resulting from the appropriate sequence of ascent and
descent commands.
If the search is not successful, an error occurs,
neither the current expression nor the chain is changed: B
"P
«NULL
and
X) Z)
"F COND P
COND ?
"P
.."«NULL X)
Here
Z)
the search failed to find a
£!!!!!!
following the current expression,
al though of course a cond does appear earlier in the structure.
This last
example illustrates another facet of the error recovery mechanism: to avoid
further confusion when an error occurs, all commands on the line beuond the one
which caused the ,error (and all comands that may have been typed ahead while
the editor was computing) are forgotten.?
We could also have used the R command (for replace) to change NUL to NULL. A
command of the form (R e 1 e 2 ) will replace all occurr~nces of e 1 in the current
expression by e 2 • There must be at'least one such occurrence or the R command
w111 generate an error.
Let us use the R command to change all
Z'.
(even
though there is only one) 1n append to Y:
6~----~~~-~~--~-------·------------------------------------~---------.---------
If the search is for an atom, e.g., F NUL, the current expression will be
the structure containing the atom.
6
F is never a NOP, i . e., if successful, the current expression after the
search will never be the same as the current expression before the search.
Thus F expr repeated without intervening commands that change the edit
chain can be used to find successive instances of expr.
?
i. e. the input burfer is cleared (and saved) (see clearbuf, Section 14).
I t can be res tored, and the type-ahead recovered via the co_and SBUFS
(alt-mode BUFS). described in Section 22.
9.7
*t (R Z Y)
*F Z
Z?
*PP
[LAMBDA (X Y)
(COND
«NULL X)
Y)
(T (CONS (CAR)
(APPEND (CDR X Y]
*
The
next
task
is
to
(CAR)
change
to
(CAR X).
We
could
do
this
by
(R (CAR) (CAR X», or by:
*F CAR
*(N X)
*p
(CAR X)
*
The expression we now want to change is the next expression after the current
expression, i.e., we are currently looking at (CAR X) in (CONS (CAR X) (APPEND
(COR X
-1,
We could get to the append expression by typing 0 and then 3 or
V»~).
or we can use the connand N)I:, which does both operations:
*p
(CAR X)
*NX P
(APPEND (CDR X V»)
*
Finally, to change (APPEND (COR X
(2 (COR X) V), or (2 (COR X»
to (APPEND (COR X) V), we could perform
V»~
and (N Y). or 2 and (3), deleting the V, and then
o (N V). However, if Y were a complex expression, we would not want to have to
retype it.
removes
Instead, we could IJse a command which effectively -inserts and/or
left
and
right
parentheses.
There
are
six of
these
comMands:
BI,BO,LI,LO,RI, and RO, for !!oth in, I!oth 2,ut, left in, left 2,ut, right in, and
r.ight .Q.ut.
Of course, we will ,always have the same number of left .parentheses
as right parentheses, because
1~he
parentheses are just a notational guide to
9.8
structure that is provided by our print program. 8 Thus, left in, left out,
right in, and right out actually do not insert or remove just one parenthesis,
but this is very suggestive of what actually happens.
In this case, we would like a right parenthesis to appear following X in (CDR X
Y) • Therefore,
we use the co_and (RI Z Z),
which means insert a' right
parentheses after the second element in the second element (of the current
expression):
*p
(APPEND (CDR X V»~
*(RI 2 2)
*p
(APPEND (CDR X) Y)
*
We have now finished our editing,and can exit from the editor, to test append,
or we could test it while still inside of the editor, by using the E command:
*E APPEND«A B) (C 0 E»
(A BCD E)
*
The E command causes, the next input to be given to evalgt.
If there is another
input following it, as in the above example, the first will be applied (apply)
to the second.
Otherwise, the input is evaluated (eval).
We prettyprint append, and leave the editor.
8-----------------~--~-------------------------------- -------------------------
Herein lies one of the principal advantages of a LISP oriented editor over
a text editor: unbalanced parentheses errors are not possible.
9.9
*PP
[LAMBDA (X Y)
(CONO
«NULL X)
Y)
(C#~R
(T (CONS
*OK
APPEND
9.2
X)
(APPEND (CDR X) Y]
Commands for the New User
As mentioned earlier, the INTERL.ISP manual is intended primarily
8S
manual,
and
and
accordingly.
the
remainder
of
this
chapter
is
organized
a reference
presented
While the commands. introduced in the previous scenario constitute
a complete set, i.e., the user could perform any and all editing operations
using just those commands, therel are many situations in which knowing the right
command(s) can save the user considerable effort.
the
We include here as part of
introduction a list of those commands which are not only frequently
applicable but also easy to us.e.
They are not presented in any particular
order, and are all discussed in detail in the reference portion of the chapter.
UNDO
undoes the
last modification
to
the structure
being edited, e.g., if the user deletes the wrong
element, UNDO will restore it.
of
should
UNDO
give
the
The availability
user
confidence
to
experiment with any and all editing coaunands, no
matter how complex, because he can always reverse
the effect of the command.
BK
like NX, except makes the expression immediately
be/ore the current expression become current.
BF
~ackwards
find.
Like
F,
except
backwards, i.e., 1n inverse print order.
9.10
searches
\
Restores the current expression to the expression
before the last ·big jump·, e.g., a find command,
an t, or another \.
For example, if the user
types F CONO, and then F CAR, \ would take him
back to the CONO. Another \ would take him back to
the CAR.
\P
like \ except it restores the edit chain to its
state as of the last print, either by P, 1, or PP.
If the edit chain has not been changed since the
last print, \P restores it to its state as of the
printing before that one, i.e., two chains are
always saved.
Thus if the user types P followed by 3 2 1 P, \P will take him back to the
first P, i.e., would be equivalent to 0 0 O.
Another \P would then take him
back to the second P. Thus the user can use \P to flip back and forth between
two current expressions.
The search expression given to the F or BF command
need not be a literal S-expression.
can be a pattern.
Instead, it
The symbol Be can be used
anywhere within this pattern to ma.tch with any
single element of a list, and -- can be used to
match with any .segment. of a list.
incorr~ct
F
(NUL Be)
definition
of
append
Thus, in the
used
cou Id have been used to find
earlier,
(NUL
X),
and F (CDR _a) or F (CDR Be A), but not F (CDR 6),
to find (CDR X V).
Note that at and -- can be nested arbitrarily
9.11
~eeply
in the pattern.
For
example. if there are many plac:es where the variable X is set, F SETQ may not
find the desired expression, nor may F (SETQ X &). It may be necessary to use
F (SETQ X (LIST
--».
However, the usual technique in such a case is to pick
out a unique atom which occurs
F commands.
I~rior
to the desired expression, and perform two
This -homing in- l)rOCeSS seems to be more convenient than ultra-
precise specification of the pattern.
5 (alt-mode)
$ 1s equivalent to -- at the character level, e.g.
VERS will match with VERYLONGATOH t as will SATOM,
SLC)NGS.
(but not SLONG) and SVSNSMS. $
F ~[SETQ VERS (CONS
a
of
inside
ne~'ted
can be
patt~rn,
e.g.,
--».
If the search is successful, the editor will print
= :followed by the atom which matched with the
$-
atom, e.g.,
-F (SETQ VERS &)
=VERYLONGATOH
-
Frequently the user will want to replace the entire current expression. or
insert something before it.
In order to do this using a command of the form (n
e1
em) or (-n e 1 .•. em)' the user must be above the current expression.
In other words, he would have to perform a 0 followed by a conunand with the
appropriate number.
However, if he has reached the current expression via an F
command, he may not know what that number is.
In this case, the user would
like a command whose effect w()uld be to modify the edit chain so that the
current
expression
became
tht!
first
expression.
element
in
a
new,
higher
current
Then he could perform the desired operation via (1 e 1 ••• em) or
(-1 e 1 •.• em). UP is provided for this purpose.
9.12
UP
after UP operates, the old current expression is
the first element of the new current expression.
Note that if the current expression happens to be
the first element in the next higher expression,
then UP is exactly the same as O.
Otherwise, UP
modifies the edit chain so that the new current
expression is a tail9 of the next higher.
expression:
*F APPEND P
(APPEND (CDR X) Y)
*Up p
.•. (APPEND & V»~
·0 P
(CONS (CAR X) (APPEND & V»~
•
The ••• is used by the editor to indicate that the
current expression is a tat 1 of the next h1gher
expression as opposed to being an element (1 •••• a
member) of the next higher expression.
Not.: if
the current expression is alreadu a tail. UP has
no effect.
(8 e 1 ••• em)
inserts e 1 ••• em before the current expression.
i.e., does an UP and then a-I.
(A e 1 .•• em)
inserts e 1 ••• em after the current expression,
i.e., does an UP and then either a (-2 8 1 ••• e.)
or an (N e 1 ••• em)' if the current expression is
the last one 1n the next higher expression.
9~-----~--------·-------------------------------------------------------------Throughout this chapter 'tail' means 'proper tail' (see Section 5).
9.13
(: 8
reJl,laces current expression by e 1 ••• 8m, i.8.,
does an UP and then a (1 e 1 ••• em).
1 ••• em)
deletes current expression: equivalent to (:).
DELETE
Earlier. we introduced the RI co_and in the append example.
The rest of the
conunands in this family: BI, BO" lI, lO, and RO, perform similar functions and
are useful in certain situations..
In addition, the commands HBO and XTR can be
used to combine the effects of several commands of the BI-BO family.
used to embed the current expression in a larger expression.
HBO is
For example, if
the current expression is (PRINT bigexpression), and the user wants to replace
it by
(CONO (FlG (PRINT bigexpression»), he could accomplish this by (LI 1),
(-1 FLG). (LI
1), and (-1 CONO) •. or by a single HBO command, page 9.47.
XTR is used to extract an expres,sion from the current expression.
For example,
extracting the PRINT expression from the above CONO could be accomplished by
( 1),
(LO
1),
(1).
and
(LO
1) (.r by a single XTR command.
The new user is
encouraged to include XTR and MBO in his repertoire as soon as he is familiar
with the more basic commands.
This ends the introductory material.
9.14
9.3
Attention Changing Commands
Commands to the edi tor fall into
t~ree
classes: commands that change the
current expression (i.e., change the edit chain) thereby ·shifting the editor's
attention,· commands that modify the structure being edited, and miscellaneous
commands, e.g., exiting from the editor. printing. evaluating expressions. etc.
Within the context of commands that shift the editor's attention, we can
distinguish among (1) those comands whose operation depends only on the
structure of the edit chain, e.g., 0, UP, NX; (2) those which depend on the
contents of the structure, i.e., commands that search: and (3) those commands
which simply restore the edit chain to some previous state, e.g., \, \P. (1)
and (Z) can also be thought of a$ local, small steps versus open ended, big
jumps.
Commands of type (1) are discussed on page 9.15-21. type (2) on page
9.21-34,
9.3.1
UP
and type (3) on page 9.34-36.
Local Attention-Changing Commands
(1) If a P command would cause the editor to type
before typing the current expression, i.e. the
current expression is a tail of the next higher
expression, UP has no effect: otherwise
(2) UP modifies the edit chain so that the old
current expression (l.e., the one at the time UP
was called)
is the first element in the new
current expression. 10
io------------------~--~----·----------------------·--------------------------If the current expression is the first element in the next higher
expression UP simply does a
the edit chain.
o.
Otherwise UP adds the corresponding tail to
9.15
Examples: The current expression in each case is
(CONO «NUll X) (RETURN
1.
V»~).
*1 P
CONO
·UP P
(CONO (Be Be»
z.
*-1 P
«NUll X) (RETURN
V»~
·UP P
«NUll X) (RETURN
*up P
... «NUll X) (RETURN
3.
V»~
V»~)
*F NULL P
(NULL X)
·UP P
«NULL X) (RETURN
*UP P
V»~
... «NULL X) (RETURN
V»~)
The execution of UP is' straightforward, except in those cases where the current
expression appears more than onl:e in the next higher expression.
For example,
if the current expression is j(A NIL B NIL C NIL) and the user performs 4
followed by UP. the current eXlpression should then be ••• NIL C NIL). UP can
determine which tail is the corlrect one because the commands that descend save
the last ta i I on an internal editor variable t
command
is executed,
las tail.
Thus after the 4
lastail 1s (NIL C NIL). When UP is called,
it first
determines if the current expression is a tail of the next higher expression.
If it is, UP is finished.
Otherwise, UP computes
memb[current-expression;next-higher-expression] to obtain a tail beginning with
the current expression .11 If 1there are no other instances of the current
expression
in
the next higher expression t
this tail is the correct one.
ii------------------------------------------------------------------------~----
The current expression should alwall$ be either a t'ail or an element of the
next higher expression.
If it is neither, for example the user has
directly (and incorrectly) manipulated the edit chain, UP generates an
error.
9.16
Otherwise UP uses lastailto select the correct tail. t2
~ 1)
n (n
adds the
~th
element of the current expression to
the front of the edit chain, thereby making it be
the new current expression.
by
UP.
Generates
an
Sets lastail for use
error
if
the
current
expression is not a list that contains at least
~
elements.
-n (n
~ 1)
adds the
~th
ele.ment from the end of the current
expression to the front of the edit chain, thereby
making it be the new current expression.
lastail for use by UP.
Sets
Generates an error if the
current expression is not a list that contains at .
least
o
~
elements.
Sets edit chain to cdr of edit chain,
thereby
making the next higher expression be
the new
current expression.
Generates an error if there
is no higher expression, i.e. cdr of edit chain is
NIL.
Note
that
0 usually corresponds to going back to the next higher
left
12----------------------------------------------------------------------------Occasionally the user can get the edit chain into a state where lastail
cannot resolve the ambiguity, for example if there were two non-atomic
structures in the same expression that were g, and the user descended more
than one level into one of them and then tri.d to come back out using UP.
In this case, UP prints LOCATION UNCERTAIN and generates an error. Of
course, we could have solved this problem completely 1n our implementation
by saving at each descent both elements and tails. However, this would be
a costly solution to a situation that arises infrequently, and when it
does. has no detrimental effects. The lastail solution is cheap and
resolves 99X of the ambiguities.
9.17
parenthesis,
but not always.
(A BCD E F B), and the user
for example,
if the current expression 15
p~trforms:
*3 UP P
... C D E F G)
*3 UP P
••• E F G)
*0 P
.•• C 0 E F G)
If the intention is to go back to the next higher left parenthesis, regardless
of any intervening tails, the c(IDlDand 10 can be used .13
10
dOEIS repeated 0' s until it reaches a point where
the current expression is not a tail of the next
hl"her expression, i.e .• always goes back to the
next higher left parenthesis.
t
sets edit chain to last of edit chain, thereby
malting the top level expression be the current
expression.
NX
Never generates an error.
effectively does an UP followed by a 2,14 thereby
mak.lng
the
current
eXlllression.
expression
be
the
next
Generates an error if the current
eXlllression is the last one in a list.
(However,
tNX described below will handle this case.)
Bt(
makes
the
current expression
be
the
previou~
i3~~--------------------------------------------------------------------------~
!O is pronounced bang-zero.
14
Both NX and BK operate by performing a ! 0 followed by an appropriate
number, i.e. there won't be an extra tail above the new current expression,
as there would be if NX operated by performing an UP followed by a 2.
9.18
expression
,in
the
next
higher
expression.
Generates an error if the current expression 1s
the first expression in a list.
For example, if the current expression is (CONO «NULL X) (RETURN
V»~):
*F RETURN P
(RETURN Y)
*BK P
(NULL X)
(NX n) n
~
1
equivalent to !!. NX commands, except if an error
occurs, the edit chain is not changed.
(BK n) n 2 1
equivalent to !!. Bk commands. except if an error
occurs, the edit chain is not changed.
Note:
!NX
(NX -n) is equivalent to (Bk n), and vice versa.
makes current expression be the next expression at
a higher level, i.e., goes through any number of
right' parentheses to get to the next expression.
9.19
for example:
frPP
(PROG «L L)
(UF L»
lP (CONO
«NULL (SETO L (CDR L»)
(ERROR!»
([NUll (COR (FHEHB (CAR L)
(CADR l]
(GO LP»)
(EOITCOM (QUOTE NX»
(SETQ UNFIND UF)
(RETURN L»
*F COR P
(COR L)
*NX
NX
?
*!NX P
(ERROR!)
*!NX P
«NULL &) (GO LP»
*!NX P
(EDITCOH (QUOTE NX»
*
!NX operates by doing O's until it reaches a stage where the current expression
is not the last expression in the next higher expression, and then does a NX.
Thus ! NX always goes through at least one unmatched right parenthesis, and the
new current expression is alwaYli on a different level, i.e. , fNX and NX always
produce different results.
For example using the previous current expression:
*F CAR P
(CAR L)
*!NX P
(GO LP)
*\P p
(CAR L)
frNX P
(CAOR l)
*
(NTH n) n I- 0
equivalent to ! followed by UP,
i~e.t
causes the
list starting with the !th element of the current
eX~tress ion
( or !!.th from the end 1f
9.20
n
< 0) to
become the current expression .16 Causes an error
if current expression does not have at least !!.
elements.
A generalized form of NTH using location specifications is described on page
9.3Z.
9.3.2
Commands That Search
All of the editor conunands that search uS,e the same pattern matching routine. 16
We will therefore begin our discussion of searching by describing the pattern
match mechanism.
A pattern pat matches with! if:
1.
pat is !! to !.
Z.
pat is
3.
pat is a number and !.9..2 to !.
4.
pat is a string and strequal[pat;x] is true.
5.
If car[pat] is the atom *ANY*, cdr[pat] is a list of patterns and
&.
pat matches ! if and only if one of the patterns on cdr[pat]
matches x.
6a.
If pat is a literal atom or string containing one or more altmodes, each $ can match an indeCini te number (including 0) of
contiguous characters in a literal atom or string, e.g.
VERS matches both VERYlONGATOH and
"VERYLONGSTRING· as do SLONGS (but not
SLONG), and SVSLSTS.
i6-~--~----~------------------------------------------------------------------~
(NTH 1) is a NOP t as is (NTH -n) where n is the length of the current
expression.
16
This routine is available to the user directly, and is described on page
9.88.
9.21
6b.
If pat is a liter'al atom or string ending in troo alt-modes, pat
matches with the first atom or string that is ·close· to pat. in
the sen se used by the spe 11 ing correc tor ( Sec t ion 17).
E •g •
CONSSSS matches with CONS, CNONCSS with NCONC or NCONC1.
The pattern matching routine always types a message of the form
=x to inform the user of the object matched by a pattern of type
6a or 6b, 17 e. g. I=VERVLONGATOH.
7.
If carr pat] is th4' atom --. pat matches! if
a.
cdr[pat]=NIL" i.e. pat=(--), e.g.
(A
_e)
matches (A) (A 8 C) and (A . 8)
In other words, -- can match any tail of a
b.
lis~.
cdr[pat] matches with some tail of !,
e.g. (A
(&» will match with (A B C (D»,
but not (A 8 C D). or (A 8 C (D) E). However,
note that (A -- (&)
_e)
will match with
(A B C (D) E).
In other words, -- can match any interior segment of a list.
8.
If car[pat] is thu atom •• , pat matches! if and only if cdr[pat]
is !9. to !.18
9.
Otherwise if ! is a list, pat matches! if car[pat]
matches car[x]. and cdr[pat] matches cdr[x].
When the edi tor is searching. t;he pattern matching routine is called to match
with element.s in the structure,. unless the pattern begins with •••• in which
case cdr of the pattern is matched against proper tails in the structure.
Thus
if the current expression is (A B C (8 C».
17-----------------------------··----------------------------------------------unless editquietflg=T.
18·
Pattern 8 is for use by plr"ograms that call the editor as a subroutine,
since any non-atomic expres~iion in 8 command tllped in by the user obviously
cannot be !!.!l to already eXi!.ting structure.
9.22
*F (8 --)
*p (8 C)
*0 F ( ••• 8 --)
*p
,
••• 8 C (8 C»
Matching is also attempted with atomic ta1ls (except for NIL).
Thus
*p
(A (8 • C»
*F C
*p
C)
Although the current expression is the atom C after the (inal command, it is
printed as ... • C) to alert the user to ,the fact that C is a tat I, not an
element.
Note that the pattern C will match with either instance of C in
(A C (8 . C». whereas ( •••• C) will match only the second C. The pattern NIL
will only match with NIL as an element, i.e. it will not match in (A I), evan
though .cddr of (A B) is NIL. However, ( •••• NIL) (or equivalently ( ••• » may
be used to specify a NIL totl, e.g. ( •••• NIL) will match with £sl!: of the
third subexpression of «A. B)(C • D) (E».
Search Algorithm
Searching begins with the current expression and proceeds in print order.
Searching
usually
means
find
the
next
instance
of
this
pattern,
and
consequently a match is not attempted that would leave the edit chain
unchanged. 19 At each step, the pattern is matched against the next element in
the expression currently being searched, unless the pattern begins with
in
which case it is matched against the next tail of the expression.
19----------~--------------~----------------------------~---------~-----~------
However, there is a version of the find command which can succeed and leave
the current expression unchanged (see page 9.26).
9.23
If the match is not successful, the search operation is recursive first in the
car direction and then
in the cdr direction,
i.e. ,
if the element under
examination is a list, the search descends into that list before attempting to
match with other elements (or tlllils) at the same level. 20
However. at no point is the totiill recursive depth of the search (sum of number
of cars and cdrs descended int(.) allowed to exceed the value of the variable
maxlevel.
At that point. the search of that element or tail is abandoned,
exactly as though the element or tail had been completely searched without
finding a match. and the search continues with the element or tail for which
the recursive depth is below maxlevel.
This feature is designed to enable the
user to search circular list structures (by setting maxlevel small). as well as
protecting him from accidentally encountering a circular list structure 1n the
course of normal editing. maxlevel is initially set to 300. 21
If . a successful match is not found in the current expression,
the search
automatically ascends to the ne,ct higher expression,22 and continues searching
there on the next expression after the expression it just finished searching.
If there is none,
it ascends again, etc.
This process continues until the
entire edit chain has been sear'ched, at which point the search fails, and an
error is generated.
If the search fails (or, what is equivalent, is aborted by
control-E), the edit chain is not changed (nor are any conses performed).
If
the search is successful, i. e., an expression is found that the pattern
20----------------------------------------------------------------------------There is also a version of the find convnand (see page 9 .27) which only
attempts matches at the top level of the current expression, i.e., does not
descend into elements, or ascend to higher expressions.
21
maxlevel can also be set to
22
See footnote on page g. 24.
I~Il,
which is equivalent to infinity.
9.24
matches, the edit chain is set to the value it would have had had the user
reached that expression via a sequence of integer commands.
If the expression that matched was a list, it will be the final link in the
edit chain, i.e., the new current expression.
If the expression that matched
is not a list, e.g., is an atolD, the current expression will be the tail
beginning with that atom,23 i.e., that atom will be the first element in the
new current expression.
In other words, the search effectively does an Up.24
Search Commands
All of the commands below set lastail for use by UP, set un find for use by \
(page 9.35), and do not change the edit chain or perform any conses if they
are unsuccessful or aborted.
F pattern
i.e., two commands: the F informs the editor that
the
next command
pattern.
is
to be
interpreted
as
a
This is the most common and useful fonm
of the find command.
If successful,
the edit
chain always changes, i.e., F pattern means find
the next instance of pattern.
If lDemb[pattern;current-expression]
is
true,
does not proceed with a full recursive search.
F
If
the value of the memb is NIL. F invokes the search
algorithm described earlier.
23~--------~---~-~-------------~---~-~--------
______
M- - - - - - - - - - - - - - - - - - - - - - - - - c~se. the current
Unless the atom is a tail, e.g. B in (A • B). In this
expression will be B, but will print as •••• B).
24,
Un less upfindflg=NIl (initially set to T) •
9.43-44.
9.25
For discussion,
see page
Thus if the current expression 1s
(PROG NIL lP (COND (-- (GO lPl»)) ... LPI ... ), F lPl will find the prog label,
not the lPl inside of the GO expression, even though the latter appears first
(in print order) in the current expression.
Note .that 1 (making the atom PROG
be the current expression), followed by F lPl would find the first lPl.
(F
pattern
sante as F pat tern, i. e., finds the !!ext instance
N)
of pattern, except the memb check of F pattern is
not; performed.
(F
Similar to F pattern, except may succeed without
pattern T)
chalnging edit chain, and does not perform the memb
che'ck.
Thus if the current expression is (COND •• ). F COND will look for the next
CONO, but (F CONO T) will 'stay here'.
(F pattern n) n
~
1
Finds
the
Equivalent
!!th
to
(F pattern N)
place
(F
that
pattern
repeated
n-l
pattern
T)
matches.
followed
times.
Each
by
time
pattern successfully matches, !! is decremented by
1. and the search continues, until!!. reaches
o.
Note that the pattern does not have to match with
!!. i.dentical expressions; it just has to match !!.
times.
Thus
if
the
current
expression
is
(FOOl FOOZ FOO3), (F FOOS 3) will find FOOl.
If the pattern does not match successfully
~
times, an error is generated and the edit chain is
unchanged (even if the pattern matched n-l times).
9.26
(F pattern) or
only matches with elements at the
(F pattern NIL)
top level of the current expression,
search
will
not
descend
into
i. e. , the
the
current
expression, nor will it go outside of the current
expression.
"ay succeed without changing edt t
chain.
For example, if the current expression is
(PROG NIL (SETQ X (CONO & &»
the SETQ, whereas (F (CONO
(CONO 6) ••• ), F CONO will find the COHO inside
--»
will find the top level CONo, i.8., the second
one.
(FS pattern 1 ••• pattern n )
equivalent
to
F
pattern t
followed
by
F
pattern 2
followed by F pattern n , so that if F
patternm fails, edit chain is left at place
patternm_1 matched.
(F- expression x)
equivalent to (F (_.
expressioQ) x),
i.e.,
searches for a structure !.!I to expression, see
page 9.22.
(ORF pattern 1 ••• pattern n ) equivalent to (F (-ANY· pattern 1 ••• pattern n ) H),
i.e., searches for an expression that is matched
by either
pattern 1,
pattern 2 , ••• or
pattern n •
See page 9.21.
BF pattern
~ackwards
find.
Searches in reverse print order,
beginning with expression immediately before the
current expression (unless the current expression
is the top level expression, in which case BF
searches the entire expression, in reverse order).
9.27
SF uses the same pattern match routine as F, and
maxlevel and upfindflg have the same effect, but
the searching begins at the
end of each list, and
des'cends into each element before attempting to
match that element.
If unsuccessful, the search
continues with the next previous element,
etc.,
until the front of the list is reached, at which
point BF ascends and backs up, etc.
For example, if the current expression is
(PROG
NIL (SETQ .X (SETQ Y (LIST Z») (CONO «SETQ W --)
--» --),
F LIST
followed by SF SETQ will leave the current expression as (SETQ Y (LIST Z)), as
will F CONO followed by BF SETQ.
sealrch always includes current expression, i. e. ,
(BF pattern T)
starts at the end of current expression and works
bac:kward, then ascends and backs up, etc.
Thus
in
the
previous
example,
where
F
CONO
followeBF
SETQ
found
(SETQ Y (LIST Z», F CONO follellwed by (BF SETQ T) would find the . (SETQ W --)
expression.
(BF pattern)
(BF pattern NIL)
sarne as BF pattern.
Location Specification
Many of the more sophisticated commands described later in this chapter use a
more general method of specifying position called a location specification.
A
location specification is a Ijtst of edit commands that are executed in the
normal fashion with two excepti.ons.
First, all commands not recognized by the
9.28
editor are interpreted as though they had been preceded by F.26 For example,
the location specification (CONO Z 3) specifies the 3rd element in the first
clause of the next COND. 28
Secondly,
if an error occurs while evaluating one of the co_ands in the
location specification, and the edit chain had been changed. i.e., was not the
same
as
it
specification.
was
at
the
beginni~g
of
that
execution
the location operation· will continue.
of
the
location
In other words,
the
location operation keeps going unless it reaches a state where it detects that
it is
I
looping', at which point it gives up.
Thus, if (CONO Z 3) is being
located, and the first clause of the next CONO contained only two elements, the
execution of the command 3 would cause an error.
The search would then
continue by looking for the next CONO. However, if a point were reached where
there were no further COHOs, then the first command, COHO, would cause the
error; the edit chain would not have been changed, and so the entire location
operation would fail, and cause an error.
The IF conunand in conjunction with the II function provide a way of using
arbitrary predicates applied to elements in the current expression.
will
be
described
1n detail
later in
the chapter,
along with
IF and
II
examples
illustrating their use in location speCifications.
Throughout this chapter,
specification.
the meta-symbol ,
is used to denote a location
Thus' is a list of commands interpreted as described above.
,
can also be atomic, in which case it is interpreted as list[@].
26----------------------------------------------------------------------------Normally such commands would cause errors.
26
Note that the user could always write F COHO followed by 2 and 3 for
(COHO Z 3) if he were not sure whether or not COHO was the name of an
atomic command.
9.29
(lC • (f)
pry, e.g. CADR->CAAR.
Note that the S feature can be used to delete or add characters, as well as
replace them.
For example, (R $1 $) will delete the terminating l's from,all
Similarly, if an alt-mode in ! does not have a mate
literal atoms and strings.
in
the characters matched by the S are effectively deleted. For example,
(R $1$ $) will change AND/OR to ANO. 66 l can also be a list containing
~,
alt-modes,
e.g.
(R 11 (CAR
I>:~
will
change
FOOl
to
(CAR FOO), FIE1
to
(CAR FIE).
If !
does not contain alt-modes, ,
83 - - i; -;-;; ;~~~; -;-~~~i~~:
not-
matter
appearing in I
-; -
whether
refers to the entire
;h;; -i; -~;;;
~ ~j.-li-~~- -r-;p-l-a~-e-d- -b-;-; -;;;;;; ~ - -;;;;; !
or
l
themselves
are
strings,
and (R "SOS" "SAS·)
equivalent.
Note also thillt x will never match with a number,
(R S1 SZ) will not change 11 to-12.
(R SOS SAS), (R "SOS" SAS), (R SDS "SAS"),
i.e.
are
i.e.
64
Note that CAOOR was not changed to CAAAR, i.e. (R SDS SAS) does not mean
replace every D with A, but replace the first 0 in every atom or string by
A.
If the user wanted to replace every 0 by A, he could perform
(LP (R SOS SAS».
66
However, there is no similar operation for changing ANDIOR to OR, since the
first $ in l always corresponds to the first I in !, the second I in ~ to
the second 1n !, etc.
9.58
expression matched by!. e.g. (R LONGATOH 'S) changes LONGATOH to 'lONGATOM,
(R (SETQ X &) (PRINT S» changes every (SETQ X &) to (PRINT (SETQ X &».88
Since
(R $x! $y$)
is a frequently used operation for replacing ~haracters, the
following command is provided:
CRC x
equivalent to
y)
Rand RC change all instances of ! to l.
(R
$xI $y$)
The commands Rl and Ret are available
for changing just one, (i.e. the first) instance of ! to l.
(Rt x y)
find the first instance of ! and replace it by
(Rei x y)
(Rl IxI Iy$).
~.
In addition. while Rand RC only operate within the current expression, Rt and
RCt will continue searching, a la the F command, until they find an instance of
!, even if the search carries them beyond the current expression.
switches the nth and mth elements of the current
(SW n m)
expression.
for example, if the current expression is
(LIST (CONS (CAR X) (CAR
V»~
(CONS (CDR X) (CDR
V»~),
(CONS (CAR X) (CAR
V»~).
(SW 2 3) will modify it to be
(LIST (CONS (COR X) (COR
and
m is
V»~
The relative order of !!.
not important, i.e., (SW 3 2) and (SW Z 3) are equivalent.
66---~--------------------------------------------------~---------------------If x is a pattern containing an alt-mode pattern somewhere within it, the
characters matched by the alt-modes are not available. and for the purposes
of replacement, the effect is the same as though x did not contain any altmodes. For example, if the user types (R (CAR FS) (PRINT S», the second I
will refer to the entire expression matched by (CAR FS).
9.59
SW'
~th
uses the generalized
NTH
conunand to find the
and mth elements, a la the DI-DO commands.
Thus in the previous example, (SW CAR CDR) would produce the same result.
Commands That Print
9.5
PP
prettyprints the current expression.
P
prints the current expression as though printlevel
were set to 2.
(P
m)
prints mth element of current expression as though
~lntlevel
(P 0)
(P
SalDe
m n)
were set to 2.
as P
pr:lnts mth element of current expression as though
ID[lntlevel were set to ft.
prints current expression as though pr1ntlevel
(P 0 n)
we."e set to !!.
?
Both
sBllle
(P
m)
and
(P
m n)
use
as
(P
0 100)
the generalized
NTH
command
to
obtain
the
corresponding element, so that !! does not have to be a number, e.g. (P COHD 3)
will work.
PP
causes all comllu!nts to be printed as
9.60
--COMMENT--
(see Section
P and ?print as .-COMMENT-. only those comments that are (top level)
elements of the current expression. 81
14) .
PP*
prettyprints
current
expression,
including
comments.
PP* is equivalent to PP except that it first
reset~
.*comment*·flg to NIL (see
Section 14). In fact, it is defined as (KESETVAR *-COMMENT**FLG NIL PP), see
page
9.77.
PPV
prettyprints current expression as a variable,
i.e. no special treatment for LAMBDA, CONO, SETQ,
etc., or for CLISP.
PPT
prettyprints current expression,
printing eLISP
translations, if any.
a~----------------------------------------------------------------------------Lower expressions are not really seen by the editor; the printing command
simply sets printlevel
.n~
calls print.
9.61
9.6
Commands That Evaluate
E
o1;,ill "he" tllped in,68 causes the editor to call
li.spx giving it the next input as argument. B9
Example: *E BREAK(FIE FUM)
(FIE FUM)
*E (FOO)
(FIE BROKEN)
(E x)
evaluates !. i.e.. performs eval[x]. and prints
the result on the teletype.
(E x T)
The (E x)
s~me
as (E .x) but does not print.
and (E x T) commands are mainly intended for use by macros and
subroutine calls to the editor'; the user would probably type in a form for
evaluation using the more convenient format of the (atomic) E cODlDand .•
Example: (I 3 (GETD (QUOTE Foo») will replace the 3rd element of the current
expression with the definition or roo. 70 (I N Foo (CAR FIE»
will attach the
69
1 ispx is used by evalqt Bind break for processing teletype inputs.
If
nothing else is typed on the same line, lispx evaluates its argument.
Otherwise, lispx applies it to the next input. In both cases, lispx prints
the result. See above example, and Sections 2 and 22.
70
The I command sets an internal flag to indicate to the structure
modi fica tion cODlDands not tell copy expression( s) when inserting, replacing,
or attaching.
9.62
value of foo and £!r of the value of fie to' the end of the current expression.
(I
F= FOO T) will search for an expression
~
to the value of foo.
If £ is not an atom, £ is
evalu~ted
also.
FOO), if !.!a is NIL,
Example: ,(I (CONO «NULL FLG) (QUOTE -1»
(T-1»
the value of foo before the first
of .the current expression, otherwise
el~ment
~nserts
replaces the first element by the value of foo.
is an NLAHBDA. NOSPREAD function (not a command).
Its value is what the current expression would be
after executing the edit commands com! ••• comn
starti~g from the present edit chain.
Generates
an error if any of com 1 thru comn cause errors.
The current edit chain is never changed.?1
Ex~mple:
(I R(QUOTE X) (II (CONS •• Z»)
expression by the first
The
I
~
replaces all
XiS
in
the current
containing a Z.
command is not very convenient for computing an entire edit command for
execution. since it computes the comand name and its arguments separately.
Also, the
I
command cannot be used to compute an atomic commande, The following
two commands provide more general ways of computing commands.
(COMS Xl ••• "n)
Each Xi is evaluated and its value is executed as
a cODlDand.
7i----------~~-----~---~---------------------------·-- ---------~---------------
Recall that A, 0, :, INSERT, REPLACE, and CHANGE mate special checks for I I
forms in the expressions used for inserting or replacing, and use a copy of
II form instead (see page 9.43). Thus, (INSERT (II 3 2) AFTER 1) is
equivalent to (I INSERT (COPY (II 3 2» (QUOTE AFTER) 1).
9.63
For example, (COMS (CONO (X (LIST 1 X»»
will replace the first element of the
current expression with the value of ! if non-NIL, otherwise do nothing.?2
executes com •••• comn "
is mainly useful in conjunction with the COMS command.
COHSQ
For example,
suppose the user wishes to comlllUte an entire list of comands for evaluation,
as opposed to computing each c,olIIDand one at
8
time as does' the COPIS cOlIIDand.
He would then write (COMS (CONS (QUOTE COMSQ) x»
commands"
9.7
e.g •• (COMS (CONS (QUI)TE COMSQ) (GETP FOO (QUOTE COMMANDS»».'"
Conunands That Test
generates an error unless the value of eval[x] is
(IF x)
true,
i.e.,
if
eval[x]
eval[x]=NIl, IF will
For
where x computed the list of
some editor' commands,
~ause
causes
an
error
or
an error.
the occurrence of an error has a well defined
mean ing, i. e ., they use errors
example, an error condition in
1;0
8
branch on, as cond uses NIL and non-NIL.
For
location specification may simply mean -not
this one, try the next.- Thus the location specification
(IPlUS (E (OR (NUHBERP (II 3»
second argument is a number.
provides
(ERRORI»
T»
specifies the first IPlUS whose
The IF comand,
by equating NIL to error ~
a more natural way of accomplishing the same result.
equivalent location specification is (IPLUS (IF (NUMBERP (II 3»».
9.64
Thus,
an
The IF command can also be used to select between two alternate lists of
commands for execution.
(IF x coms 1 coms Z)
If eval[x] is true,
execute coms 1 ; if eval[x]
causes an error or is equal to' NIL, execute
coms ·73
z
for example,
the command (IF (READP T) NIL (P»
will print the current
expression provided the input buffer is empty.
IF can also be written as:
(IF x coms t
)
if eval[xl' is
true,
execute
coms t ;
otherwise
generate an error.
(LP • coms)
repeatedly executes
~,
a list of commands,
until an error occurs.
For example, (lP F PRINT (N T»
expression.
will attach a T at the end of every print
(lP F PRINT (IF (II 3) NIL «N T»»
will attach a T at the end of
each print expression which does not already have a second argument. 14
When an error occurs. lP prints n OCCURRENCES.
73----~-~--~--~-------------------------------------~---------------~----------
Thus IF is equivalent to (COMS (CONS (QUOTE COHSQ) (COND
( (CAR (NlSETQ (EVAl X») COMS!)
(T COMSZ»».
74
i. e . the form (II 3) wi 11 cause an error if the edit conunand 3 causes an
error, thereby selecting «N T» as the list of ,commands to be executed.
The IF could also be written as (IF (CDDR (II» NIL «N T»).
9.65
whElre
n
is
the
number
successfully executed.
of
times
The edit chain is left
of the last complete successful execution of
(lPQ . coms)
SaDie
as
LP
but
was
~
does
not
print
the
a~
~.
message
n C-CCURRENCES.
In order to prevent non-terminating loops, both lP and lPQ terminate when the
number of iterations reaches m1Clxloop , initially set to 30. 76 , Since the .ed;1t
chain 15 left as of the last successful completion of the loop, the user can
simply continue the LP cODlDand ",ith REDO (Section ZZ).
(SHOW • x)
! 1,5 a list of patterns.
all
instances of the
SHOW does a LPQ printing
indicated
e.Ql. (SHOW FOO (SETQ FIE 6»
andl all (SETQ FIE 6)' s.
expression(s),
will print all FOO's
Generates an error if
there aren't any instances of the expression(s).
(EXAM •
x)
lik.e SHOW except calls the editor recursively
(via the TTY:
cODlDand described on page 9.70) on
each instance of the indicated espressfon( s) so
that the user can examine and/or change them.
(ORR coms l .•• comsnl
begins by executing coms l , a list of, commands.
If no error occurs, ORR is finished. Otherwise,
ORR
ORR
restores the edit chain to its original value,
and continues by executing coms Z ' etc. If none of
the cODlDand lists execute without errors, i.e.,
9.66
the ORR -drops off the end-, ORR generates an
error.
Otherwise, the edit chain is left as of
the completion. of the first cOPlDand list which
executes without an error. 76
For example, (ORR (NX) (!NX) NIL) will perform a NX, if possible, otherwise a
!NX, if possible, otherwise do nothing.
(ORR (UP (1»
9.8
(BK UP (2»
Si.ilarly, DELETE could be written as
(UP (: NIL»).
Macros
Many of the more sophisticated branching commands in the editor, such as ORR,
IF, etc., are most often used in tonjunction with edit macros.
The macro
feature permits the user to define new commands and thereby expand the editor's
repertoire. 77 Macros are defined by using the'" command.,
(M c • coms)
For £ an atom, M defines £ as an atomic command. 78
Executing £ is then the same as executing the list
of commands £2m!.
For example, (M BP BK UP P) will define BP as an atomic command which does
three things. a BK, and UP. and a P.
"acros can use commands defined by macros
76 - - ~ i~ --;; --~ --~;;.;;~~- -;;;;- -i-; --p-e-r-f~~-t-I-y- --l~~~-{,-- ~~d- -~~i i--;i~;;; -- ;;;~~~;
successfully. Thus, making the last 'argument' to ORR be NIL will insure
that the ORR never causes an error. Any other atoll is treated as (atom) t
i.e., the above example could be written as (OR NX !NX NIL).
77
However built in commands always take precedence over macros, i.e. t
editor's repertoire can be expanded. but not redefined.
78
If a macro is redefined, its new definition replaces its old.
g.67
the
as well as built in conunands in their definitions.
For example, suppose Z is
defined by (M l -1 (IF (READP 'f) NIL (P»),
does a -1, and then if
nothing
has
been
typed,
P.
a
i.e. l
Now
we
zz
define
can
by
(M II -1 l), and ZZZ by (M III -1 -1 Z) or (" Zll -1 ll).
Macros can also define list commands, i.e., commands that take arguments.
(M (c) (arg t ••• argn ) • coms)
~ an atom.
"defines ~ as a list command.
EXEtcuting (c e 1 ••• en) is then performed by
substituting
thr'oughout
For example, we could define
e1
£Q!!!!,
for
arg l , ... en
for
argn
and then executing £Q!!!!.
more general BP by (M (BP) (N) (BK N) UP P).
ill
Thus. (BP 3) would perform (BK 31), followed by an UP, followed by a P.
A list command can be defined via a macro so as to take a fixed or indefinite
number of 'arguments', as with spread vs. nospread functions.
The form given
above specified a macro with a fixed number of arguments, as indicated by its
argument
list.
If the
'argunlant list'
is atomic,
the command
takes
an
indefinite number of argumants.?~
(M (c) arg . coms)
~,
arg both atoms, defines
(c e 1
substituting (e 1
Executing
command.
for
executing
For example,
the command 2ND,
arg
~
as a list cOlIIDand.
en)
is
en) ,
i.e. ,
throughout
performed
by
of
the
cdr
£Q!!!,
and
then
~.
page 9.30.
( " ( 2ND) X (ORR « lC • X) (LC • X»».
9.68
can be defined as a macro by
Note that for all editor commands, 'built in' conunands as well as commands
defined by macros,
independent.
atomic definitions and list definitions are completelu
In other words, the existence of an atomic definition for £ in no
way affects the treatment of £ when it appears as £!r of a list command, and
the existence of a list definition for £ in no way affects the treatment of £
when it appears as an atom.
In particular, £ can be used as the name of either
an atomic command, or a list command, or both.
In the latter case,
two
entirely different definitions can be used.
Note also that once £ is defined as an atomic command via a macro definition,
it will not be searched for when used in a location specification,. unless it is
preceded by an F. Thus (INSERT -- BEFORE BP) would not search for BP, but
ins tead perform a BK. and UP, and a P, and then do the insertion.
The
corresponding also holds true for list commands.
Occasionally. the user will want to employ the S command in a
some temporary result.
(H
(SW)
mac~o
to save
For example, the SW command could be defined as:
(S
(I 1 FOO)
(N H) (NTH N)
FOO 1) HARK 0 (NTH M)
~
(I 1 FIE»
(S
FIE 1)
80
Since this version of SW sets foo and fie, using SW may have undesirable side
effects, especially when the editor was called from deep in a computation, we
would have to be careful to make up unique names for dummy variables used in
edi t
macros, which is bothersome.
Furthermore, it would be impossible to
define a command that called itself recursively while setting free variables.
The BIND command solves both problems.
80----------------------------------------------------------------------------A more elegant definition would be:
(SW) (N H) (NTH N) HARK 0 (NTH H) (S FIE 1) (I 1 (II .. 1»
..... < I 1 FIE», but this would still use one free variable.
(H
9.69
(BIND . coms)
b1.nds
three
dummy
variables
11,
12,
13,
(1ni tialized to NIL), and then executes the edit
cOlIIDands
£Q.!!!!.
Note that these bindings are only
in effect while the commands are being executed,
and that BIND can be used recursively;
it will
rebind '1, 12, and '3 each time it is invoked. 81
Thus we could now write SW safely as:
(M (SW (N M) (BIND (NTH N) (5 '1 1) HARK 0 (NTH H) (5 12 1)
(I 1 11)
~
(I 1 12»».
User macros are stored on a lisit usermacros.
The prettydef command USERHACROS
(Section 14), is available for dumping all or selected user macros.
9.9
NIL
Miscellaneous Commands
unless preceded by F or 8F, is always a NOP.
Thus
extra right parentheses or square brackets at the
ends of commands are ignored.
TTY:
calls the editor recursively.
The user can then
tYJ,e in commands, and have them executed.
The
TT": comand is completed when the user exits from
thet lower editor.
The TTY: conunand is extremely
u~.eful.
(see OK and STOP below).
It enables. the user to set up a complex
operation, and perform interactive attention-changing commands part way through
8i-~~------------------------------------------------- -------------------------
BIND is implemented by (PltOG (II 12 13) (EOITCOMS (COR COM») where com
corresponds to the BIND command, and editcoms 15 an internal editor
function which executes a list of comands.
9.70
For example the command (MOVE 3 TO AFTER CONO 3 P TTY:) allows the user to
it.
interact, in effect,
within the MOVE command.
Thus he can verify for himself
that the correct location has been found, or complete the specification ·by
hand. It In effect, TTY: says • I 'Ii tell you what you should do when you get
there.·
The TTY: command operates by printing TTY: and then calling the editor.
The
initial edit chain in the lower editor is the one that existed in the higher
editor at the time the TTY: command was entered.
Until the user exits from the
lower editor, any attention changing commands he executes only affect the lower
editor's edit chain. 82 When the TTY: command finishes, the lower editor's edit
chain becomes the edit chain of the higher editor.
OK
exits from the editor
STOP
exits from the editor with an error.
Mainly for
use in conjunction with TTY: co_ands that the
user wants to abort.
Since all of the commands in the editor are errorset protected, the user must
exit from the editor via a command. 83 STOP provides a way of distinguishing
between a successful and unsuccessful (from the user's standpoint) ed'iting
session.
For example, if the user, is executing (MOVE 3 TO AFTER COHD TTY:),
and he exits from the lower editor with an OK, the HOVE cOlIIDand will then
82-~--~-------------·--------~------------------------ -------------------------
Of course, if the user performs any structure modification commands while
under a TTY: conunand, these will modify the structure in both editors,
since it is the same structure.
83
Or by typing a control-D. STOP is preferred even if the user is editing at
the evalgt level, as it will perform the necessary 'wrapup' to insure that
the changes made while editing will be undoable (see Section 22).
9.71
complete its operation.
If the user wants to abort the MOVE command, he must
make the TTY: command generat'B an error.
lower editor with a STOP command.
He does this by exiting from the
In this case, the higher editor's edit chain
will not be changed by the TTY: command.
SAVE
exits from the editor and saves the 'state of the
edi t
I
on the property list of the function or
variable
being
edited
under
property
the
EDIT-SAVE. If the editor is called again on the
same
structure,
·continued,· i.e.,
the
editing
is
the edit chain,
effectively
mark
list,
value of un find and undolst are restored.
For example:
*p
(NUll X)
*F COND P
(COND (& &) (T
*SAVE
FOO
&»
.
"'EOITF(FOO)
EDIT
*p
(COND (& &) (T
&:~)
*\ p
(NUll X)
*
SAVE is necessary only if the user is editing many different expressions; an
exit from the editor via OK alwlsys saves the state of the edit of that call to
the editor. 84 Whenever the editctr is entered, it checks to see if it is editing
the same expression as the last one edited.
In this case, it restores the mark
84-------~----------~------------·--------------------------------------------~
on the property list of the atom EDIT, under the property name lASTVALUE.
also remprops EDIT-SAVE frOID the property list of the function or
variable being edited.
OK
9.72
list, the undolst, and sets un find to bl the edit chain as of the previous exit
from the editor.
For example:
"EDITF(FOO)
EDIT
*p
(LAMBDA (X) (PROG6 6 lP • • • 6»
~P
(COND 6 Be)
*OK
FOO
any nu.olr of lispx inputs
except for calls to the editor
.
"EOITF(FOO)
EDIT
*p
(LAMBDA (X) (PROG Be • lP 6 •• 6»
*\ p
(COND '"
*
&)
Furthermore, as a result of the history f.ature (section 22), if the editor 1s
called on the same express~on within a certain nuaber of lispx inputs,86 the
stata of the edit of that expression is restored, regardless of how •• ny other
expressions .ay have been edited in the •• anti.,.
86-~---~~--~-~------------------------------~-----·~-------------------~-------
Namely, the size of the history list. initially 30, but it can be increased
the user.
by
9.73
for example:
"EDITF(FOO)
EDIT
•
•p
(COND (3& 3&) (6 3&) ( 3& ) (T 6»
·OK
FOO
.
less than 30 lispx input,. including editing
.
"EDITF(FOO)
EDIT
.\ P
(COND (Be Be) (3& Be) (Be) (1 Be»
•
Thus the user can always contJlnue editing,' including undoing changes from a
previous editing session, if
(1)
No other expressions have been edited since that seS5ion;86 or
(2)
That session was
(3)
It was ended with a SAVE cOllllland.
~sufficientIY'
•
RAISE
recent; or
•
•
is an
edit macro
(I 1 (U-CASE
(II
derine~
as
UP
followed
by
1»), i. e • it raises to upper-
case the current expression, or if a tail, the
first element of the current expression.
LOWER
Similar to RAISE, except uses I-case.
86------------------------------·----------------------------------------------Since saving takes place at ext t time, intervening calls that were abo ....'ted
via control-D or eXited via . STOP will not afrect the editor' s memory of
this last session.
9.74
First does a RAISE. and then lowers all but the
CAP
first character. i.e. the first character 1s left
capitalized.
Note: RAISE, LOWEll. and CAP .re all NOPs if the corresponding atom or string t&
alreadu in that state.
(RAISE
equivalent
x)
to
(I R (L-CASE x) x),
i.e.
changes
every lower-case x to upper-case in the current
expression.
(LOWER
similar to RAISE,
x)
CASE
except
performs
(I R x (L-
x».
Note in both (RAISE x) and (LOWER x), ! is typed in in upper case.
REPACK
Permits the 'editing' of an atom or string.
For example:
*p
-THIS IS A LOGN STRING-)
REPACK
*EOIT
P
(T HIS X I S X A X LOG N % S T R 1 N G)
Jr(SW G N)
*OK
87
-THIS IS A LONG STRINGl1li
REPACK operates by calling the editor recursively on unpack of the current
i~------------------~---------------------------------------------------------Note that this could also have been accomplished by (R SGNS SNGS) or s1mply
(RC GN
HG).
9.75
expression, or if it is a list, on unpack of its first element.
If the lower
editor is exited successfully, i.e. via OK as opposed to STOP, the list of
atoms is made into a single atom or string, which replaces the atom or string
being 'repacked.' The new atom or string is always printed.
(REPACK
@)
(LC
does
')
followed
by
e.g.
REPACK,
(REPACK THISS).
(;
• x)
! is the text of a comment.
; ascends the edit
chl!in looking for a •safe' place to insert the
cOIJwent, e. g. • in a cond clause. after a I!.!:2.S
stlstement, etc., and inserts (* •
po:Lnt,
if
possible,
eX«UDple,
if
(FACT (SUB1
N))
the
otherwise
current
alter that
x)
before.
For
expression
is
in
[COND
( (ZEROP N) 1)
(T (ITIHES N (FACT (SUBI
N]
(; CALL FACT RECURSIVELY) would insert
(*
CALL FACT RECURSIVELY)
be/ore
the
itimes
eX~lression. 88
; does not change the edit chain, but unfind is
set to where the comment was actually inserted.
JOINe
is used to join two neighboring COND's together,
e.g. (CONO clause l clause Z)
followed
by
88----------------------------------------------------------------------------If inserted after the i tirr!!.!,. the comment would then be (incorrectly)
retu.rned as t. he value of the cond. However. if the cond was itself a 2!:QD.
statement, and hence its value was not being used, the comment coula-bi
(and would be) inserted after the itimes expression.
9.76
(CONO clause 3 clause 4 )
becomes
(CONO clause l clauseZ clause 3 clause 4 ).
JOINC
does an (F CONO T) first so that you don't have to
be at the first COND.
spli ts one CONO into two.
!
specifies the last
clause in the first COND, e.g. (SPLITC 3) splits
(CONO clause l clause Z clause l clause 4 )
into
(CONO clause l clause Z)
(CONO clause l clause4 ).
Uses generalized NTH command, so that ! does not
have ,to be
(SPLITC
a number,
RETU~N).
e.g.,the
user
can
say,
meaning split after the clause
containing RETURN.
SPLITC also does an (F COHO T)
first.
CL
Clispifies current expression.
See Section 23.
ow
Owimifies current expression.
See Section 17 and
23.
(RESETVAR var for. • coms)
executes
~
while Y!r is reset to the value of
form, and then restores !!!., i •e •
effect 1ve ly
calls the function resetvar (Section 5).
9.77
9.10
UNDO
Each conunand that causes
struc1~ure
modification automatically adds an entry to
the front of undolst that contains the information required to restore all
pointers that were changed by that command.
UNDO
undoes
the
modification
last,
i.e.
cODlDand
most
that
recent,
has
not
structure
yet
been
undone,89 and prints the name of that command,
e.!~.,
"SO UNDONE. The edit chain is then exactlll
Whist it was before the·' undone' coaunand had been
pelr-formed. 90 If there are no cODlDands to undo,
UNI)O types NOTHING SAVED.
I UNDO
undoes all modifications performed during this
edjLting session, i.e.
this call to the editor.
As each command is undone, its name is printed a
la UNDO. If there is nothing to be undone, IUNDO
pr:l.nts NOTHING SAVED.
89----------------------------------------------------------------------------Since UNDO and 'UNDO cause structure modification, they also add an entry
to undolst. However, UNDO ~nd !UNDO entries are skipped by UNDO, e.g., if
the user performs an INSERT, and then an MBD, the first UNDO will undo the
MBD, and the second will undo the INSERT. However, the user can also
specify precisely which cflmmands he wants undone by identifying the.
corresponding entry on the history list as described in Section 22. In
this case, he can undo an UNDO command, e.g. by typing UNDO UNDO, or undo a
!UNDO command, or undo a command other than that most recently performed.
90
Undoing an event containing an I. E. or S command will also undo the side
effects of the evaluation(s), e.g. undoing (I 3 (/NCONC FOa FIE» will not
only restore the 3rd element but also restore FOO. Similarly, undoing an B
command will undo the set. See discussion of UNDO in Section 22. (Note
that if the I command was typed directly to the editor, INCONC would
automatically be substituted for NCONC as described in Bection 22.)
9.78
Whenever the user conttnue$ an editing session
8S
described on page 9.12-14,
the undo information of the previous session is protected by inserting a
special blip, called an undo-block, on the front of undolst.
This undo-block
will terminate the operation of a IUNDO, thereby confining its effect to the
current session,
will si.ilarly prevent an UNDO command from operating on
~nd
cOmMands executed in the ,revious session.
Thus,
if
executes
the user enters the editor continuing a session, and immediately
an
UNDO
or
IUNDO,
the
editor
will
type
BLOCKED
instead
of
NOTHING SAVED. Si.ilarly, if the user executes several cormnands and then undoes
them all, another UNDO or IUNDO will also cause BLOCKED to be typed.
UNBLOCK
re.oves an undo-block.
blocked
state,
i.e.
If executed at
if
UNDO
or
IUNDO
a non-
could
operate, types NOT BLOCKED.
TEST
adds an undo-block at the front of undolst.
Note that TEST together with fUNDO provide a 'tentative' mode for editing, i.e.
the user can perfor. a number of changes, and then undo all of thelll with a
Single !UNDO command.
9.79
Editdefault
9.11
Whenever a command is not recol}nized, i.e.; is not "built' in' or defined as a
macro, the editor calls an in1;ernal function, editdefault,,"t'o'-determine what
action to take. 91 If a location specification is being \ executed, an 'internal
flag informs edi tderault to treat the command as though it bad 'bean'prec'eded by
an F.
If the command is a list, an attempt is made to perform spelling correction on
car of the command 92 using editcomsl,: a list of' all !ist edit corntnand~. 93 If
spelling correction is successful,94 the correct coimnand name is' 'rplacaed into
the
command.
and
the
editor
In other words, if the user types
continues
(lP F
~RINT
by
executing
the
command.
(HBBD AND (NUll FlG»)), only one
spelling correction will be necessary to change HBBD to MBD.
If spelling
correction is not successful, an error is generated.
If the command is atomic, the
pl~ocedure
followed is a little more elaborate.
9j------------------------------·----------------------------------------------Since ed i tdefau 1 t is part of the edit block. the user cannot advise or
redefine it as a means of alJlgmenting or extending the editor. However, the
user can accomplish this via edituserfn.
If the value of the variable
edituserfn is T, editdefault calls the function edituserfn giving it the
command as an argument. If edituserfn returns a non-NIL value, its value
1s interpreted as a singlEt command and executed. Otherwise, the error
correction procedure described below is performed.
92
unless dwimflg:NIl. See Sect.1on 17 for discussion of spelling correction.
93
When a macro is defined vi.. the H conunand, the command name is added to
edi tcomsa or editcomsl. depending on whether it is an atomic or list
command. The prettydef cO~land USERHACROS (Section 14), is aware of this,
and provides for restoring !ditcomsa and editcomsl.
.
94
Throughout this discussion. if the command was not typed in directly, the
user will be asked to approve the spelling correction. See Section 17.
9.80
1)
If the command is one of the list commands, i.e., a member of editcomsl,
and there is additional input on the same teletype line. treat the entire
line as a single list command. 96 Thus, the user may omit parentheses for
any list command typed in at the top level (provided the command 1s not
also an atomic command, e.g.
NX, BK). For example,
*p
(COND (& &) (T &»
*XTR 3 Z]
·HOVE TO AFTER lP
*
If the command is on the list editcomsl but no additional input 1s on the
teletype line, an
erro~
is generated, e.g •
•p
(COND (& &) (T &»
*MOVE
MOVE?
•
If the command is on
editcomsl, and not typed in directly, e.g. it appears
as one of the commands in a lP command, the procedure is similar. with the
rest
of
the
command
stream
at
that
level,
being
treated
as
"the teletype line", e.g.
(lP F (COND (T &»
Z)
XTR 2 2).98
If the command was typed in and the first character in the command is an 8,
96----------------------------------------------------------------------------The line is read using readline (Section 14).
Thus the line can be
terminated by a square bracket, or by a carriage return not preceded by a
space.
96
Note that if the command is being executed in location context, editdefault
does not get this far, e.g. (HOVE TO AFTER COND XTR 3) will search for XTR,
not execute tt. However, (HOVE TO AFTER COND (XTR 3» wll1 work.
9.81
treat the 8 as a mistyped left parenthesis, and and the rest of the line as
the arguments to the command, e.g.,
-p
(COND (& Be) (T 8:»
-8-2 (Y (RETURN Z»)
=(-2
-p
(COND (Y Be) (Be Be) (T Be»
3)
I f the command was typed il1l, is the name of a function. arid is followed by
NIL or a list £!r of which is not an edit command, assume the user forgot
to type E and means to apply the function to its arguments, type -E and the
function name, and perform the indicated computation, e.g.
-BREAk(FOO)
=E BREAK
(FOO)
•
4)
If the last character in the cODlDand is P, and the first n-l characters
comprise a number, assume that the user intended two cODlDands, e.g.,
-p
(COND (& 8r) (T 8r Jt )
-OP
=0 P
(5ETO X (COND Be &»
5)
Attempt spelling correction using editcomsa, and if successful,97 execute
the corrected command.
6)
Otherwise,
if there is additional input on the same line, or cODlDand
stream, spelling correct using editcomsl, e.g.,
~~--;;;-;;;;;;;;-;;-;;;;-;:;;:-------------------------------------------------
9.82
*HBBO SETQ X
=HBD
..
7)
Otherwise, generate an error.
9.12
Editor Functions
edite[expr;coms;atm]
edits an expression.
Its
value
is
element of editl[list[expr]:coms;atm].
the
last
Generates
an error if expris not a list.
editl[l;coms;atm:mess]
edIt1 98 i$ the edItor.
Its first argum~nt is the
edit chain, and its value is an edit chatn, namely
gg
the value of ! at the time editl is exited.
~
is
an
optional
list
of
commands.
for
interactive editing, coms is NIL. In this case,
editl types EDIT and then waits for input from
teletype. tOO Exit occurs only via an OK, STOP, or
SAVE cOlIIDand.
If £em! is not NIL, no message is typed, and each
98----------------------------------------------------------------------------edit-e", not edit-one.
99
!
is a specvar, and so can be examined or set by edit conunands. for
example, t is equivalent to (E (5ETO l (LAST L» T). However, the user
should only manipulate or examine I directly as a last resort, and then
with caution.
-
NIL, editl types it instead of EDIT. For example, the TTY:
command is essentially (SETQ l (EDITl l NIL NIL (QUOTE TTY:»).
100 If mess is not
9.83
mmnber
of £!!!!!!.
e"ecuted.
is
treated
as
a
command
and
If an error occurs in the execution of
one of the commands, no error message is printed,
the rest of the commands are ignored, and e'ditl
e)tits with an error, i.e. the effect is the same
a!; though a STOP command had been executed.
If
all comands execute successfully, editl returns'
the current value of
at,!! is optional.
!.
On calls from edi tf, it is the '
name of the function being edited; on calls from
editv, the name of the var'iable, and calls from
ed!!2,
the atom whose
edited.
property list
is
being
The property list of atm is used by the
SAVE command for saving the state of the edt t.
Thus SAVE 'will not save anything if !!!!!=NIL, 1.e.
wh'sn editing arbitrary expressions via edi te or
editl directly.
editIO[l,coms;messieditlflg].fO.f
like
editl
except
does
not
rebind
or
initialize the editor's various state variables,
such as lastail, unfind, undolst, marklst, etc.
editf[x]
nli~bda.
car[x]
nospread function for editing a function.
is
the name of
the
opt;ional list of cODUDands.
function,cdr[x]
For the' rest of 'the
dislcussion, fn is car[x], and £!!!!.! is cdr[x].
The value of editf is fn.
9.84
an
(1) In
the most common case,
fn
is an expr,
and !.!!!!!. simply ,performs
putd[fn;edite[getd[fn];coms.fn]].
(2) If fn
is not an expr, but has an EXPR property, edi tf prints PROP, and
performs edite[getp[fn;EXPR];coms:fn].
If edite returns
(i.e.
if the
editing is not terminated by a STOP), and some changes were made, editf
performs unsavedef[fn], prints UNSAVED, and then does putd[fn;value-ofedite].
(3)
If fn is neither an expr nor has an EXPR property, but its top level value
is a list, editf assumes the user meant to call editv, prints =EDITV, calls
edi tv and returns.
Similarly, if fn has a non-NIL property list, editf
prints =EDITP, calls editp and returns.
(4)
If fn is neither a, function, nor has an EXPR property, nor a top level
value that is a list, nor a non-NIL property list, editf attempts spelling
correction using the spelling list userwords, 102 and if successful, goes
back to (1).
Otherwise, editf generates an fn NOT EDITABLE error.
If editf ultimately succeeds in finding a function to edit, i.e. does not exit
by calling editv or editp, editf calls the function addspell after editing has
been completed. lOa Addspell 'notices' fn, i.e. sets lastword to fn, and adds fn
102---------------------------------------------------------------------------Unless dwimflg=NIL. Spelling correction is performed using the function
misspelled? If fn=NIL, misspelled? returns the last 'word' referenced,
e.g. by defineq, editf, prettyprint etc. Thus if the user defines foo and
then types editf[], the editor will assume he meant foo, type -FOO, and
then type EDIT. See Section 17.
108 Unless dwimflg=NIl.
addspell is described in Section 17.
9.85
to the appropriate spelling lists.
newfile?
If any changes were made, editf also calls
which performs the updating for the file package as described in
Section 14.
ed1tv[editvx]
nlambda, nospread function, similar to editf, for
editing yalues.
car[editvx] specifies the value,
cdr[editvx] is an optional list of co_ands.
If car[editvx] is a list, it
JLS
evaluated and its value given to edite, e.g.
EOITV«COR (ASSOC (QUOTE FOO) D'ICTIONARY»». In this case, the value of editv
1s T.
However. for most applications, car[editvx] is a variable name, i.e. atomic, as
in EOITV(FOO). If the value of this variable is NOBIND, editv checks to see if
it 1s the name of a function, and if so, assumes the user meant to call editf,
prints =EOITF, calls edi tf and returns.
Otherwise, editv attempts spelling
correction using the list ~ords.l04 Then editv will call edite on the value
of car[editvx] (or the corrected spelling thereof).
Thus, if the value of foo
is NIL, and the user performs I(EOITV FOO), no spelling correction will occur,
since foo is the name of a variable in the user's system, i.e. it has a value.
However,. edite will generate alll error, since foo's value is not a list, and
hence not editable.
If the use." performs (EOITV FOOO), where the value of fooo
is NOBINO, and foo is on the user's spelling list, the spelling corrector will
correct FOOO to FOO.
Then edi tEt will be called on the value or foo.
Note that
this may still result in an errctr if the value of faa is not a list.
When (if) edite returns, editv sets the variable to the value returned, and
calls addspeIl and newrile?
104------------------·--------------------------------------------------------Unless dwimflg=NIL. Misspelled? is also called if carr edi tvx] is NIL, so
that EOITV() will edit lastword.
9.86
The value of editv is the name of the variable whose value was edited.
editp[x] _
nlambda, nospread function, similar to editf for
editing I!roperty lists.
If the property list of
car[x] is NIL, editp attempts spelling correction
using userwords.
property
list
Then editp calls edite on the
of
spelling thereof).
car[x],
When (if)
(or
~
the
corrected
returns, editp
rplacd's car[x] with the value returned, and calls
addspell.
The value of editp is the atom whose property list
was edited.
editfns[x]
nlambda, nospread function, used to perform the
same editing operations· on
several
functions.
car[x] is evaluated to obtain a list of functions.
cdr[x] is a list of edit commands.
editfns maps
down the list of functions, prints the name of
each function, and calls the editor (via editf) on
that function. 106
For example, EDITFNS(FOOFNS (R FIE FUM»
will change every FIE to FUM in each
of the functions on foofns.
The call to the editor is errorset protected, so
i06-~:;:-~h;-~;ri~i~i~~-~r-;~i~f~;-~i;h~-b;~-----------------------------------
[MAPe (EVAL (CAR X» (FUNCTION (LAMBDA (Y)
(APPLY (QUOTE EDITF)
(CONS (PRINT Y T) (CDR Xl
9.87
that if the editing of one function causes an
error,
editfns
function. 108
will
proceed
to
the
next
Thus in the above example, if (me of the functions did not contain a FIE, the R
command would cause an errOlr,
but editing would continue with
the next
function.
The value of editfns is NIL.
edit4e[pat;x;changeflg]
i!. the pattern match routine.
~!-matches!.
Its value is T if
See page 9.21-23 for definition of
'nlatch I .107
Note:
before each search operation in the editor begins, the entire pattern is
scanned for atoms or strings containing alt-modes.
patterns
of
the
These are replaced by
form' (CONS (QUOTE $) (UNPACK atom/string»
for
6a,
and
(CONS (QUOTE SS) (CONS (NCHARS atom/string) (UNPACK atom/string»), for 6b. 108
Thus from the standpoint of !!lit4e, pattern type 6a is indicated by car[pat]
being the atom $ ($ is alt-mode) and pattern type 6b by car[pat] being the atom
$S
(double alt-mode).
106---------------------------------------------------------------------------In particular. if an error occurred while editing a function via its EXPR
property. the function would not be unsaved. In other words, in the above
example, only those functions which contained a FIE. i.e. only those
actually changed. would be unsaved.
107 changeflg is for internal use by the editor.
108 In latter case, atom/string corresponds to the atom or string up to but not
including the final two-alt-modes.
possible.
In both cases, dunpack is used wherever
9.88
Therefore, if the user wishes to call edit4e directly. he must first convert
any patterns which contain atoms or strings ending in alt-modes to the form
recognized by edit4e.
This is done with the function editfpat.
editfpat[pat;flg]
makes a copy of pat with all patterns of type 6
converted to the form expected by edit4e. 109
editfindp[x:pat;flg]
allows a program to use the edit find command as a
pure predicate from outside the editor.
expression, pat a pattern.
~
is an
The value of editfindp
is T if the command F pat would succeed,
otherwise.
NIL
editfindp calls editfpat to convert
pat to the form expected by edit4e. unless flg=T.
Thus,
if the program is applying editfindp to
several
pattern,
different
it
will
expressions
be
more
using
efficient
the
same
to
call
editfpat once, and then call editfindp with the
converted pattern and
esubst[x:y;z;errorflg;charflg]
the
!!saT.
equivalent to performing (R y x)110 with ~ as
current
expression,
i. e.
the
arguments is the same as for subst.
and/or !
can employ alt-modes.
esubst is the modified!.
tID
Note that
The
of the type that never causes a break.
9.89
value
of
~
of
~enerates an error ttt
unless charflg=T. in which case it is equivalent to (RC y x).
9.59.
111
order
See page
if I not found in!.
If errorflg-T. also prfnts
an error message of thefonl y 1.
eSlubst is always undoable.
changename[fn;from;to]
rel)laces all occurrences of from by to, in the
de1finition of fn.
If fn is an expr, changename
performs nlsetq[ esubst[ to; from;getdt tn]]].
is compiled,
(and
If fn
changename searches the literals of
all
of
its
compiler
generated
subfunctions). replacing each occurrence of from
with to. 112
The' value of changename is fn if at least one
instance of from was found, otherwise NIL.
changename is used by break and advise for changing calls to fnl to calls to
fnt-IN-rnZ.
editracefn[com]
is available to help the user debug complex edit
maClros, or subroutine calls to the editor.
If
editracefn is set to T, the function editracefn is
called whenever a command that was not typed in by
the user is about to be executed, giving it that
comrlland as its argument.
BRE~'"
options
described
However. the TRACE and
below
are
probably
sufficient for most applications.
ii2---------------------------------------------------------------------------Will succeed even if from i~; called from fn via a linked call. In this
case, the call will also be relinked to calr-to instead.
9.90
If edi tracefn is set to TRACE, the name of the
cOlIIDand and the current expression are printed.
If
editracefn=BREAK,
the
same
information
printed, and the editor goes into a break.
user can then examine the state of the editor.
editracefn is initially NIL.
9.91
is
The
Index for Section 0
Page
Numbers
(A el ... em) (edit conunand) ......••..••..••••••
AOOSP£LL[X;SPlS'T;N] ..•... _~ ••..•••••••••••••••••
AFTER (in INSERT command) (in editor) ••••••.••••
AFTER (in MOVE command) (1n editor) ............ .
(B 01 ... em) (edit command) .•..••••••••••••••••
BEFORE (in INSERT command) (in editor) ••••••••••
BEFORE (in MOVE command) (in editor) .•.•••.•••••
(BELOW com x) (edit command) ................... .
(BELOW com) (edit command) .••.••••••••••••••••••
BF (edit conunand) ....•.••••••••••••••••••••.••••
(BF pattern T) (edit command) .•.••••••••••••••••
(BI n m) (edit command) ..•••..••••••••••••••••••
(BI n) (edit command) .•...••.•••••••••••••••••••
(BIND. corns) (edit command) ••••.••••••••.••••••
BK (edit command) ............•.•••••••••.••..•••
(BK n) (n a number, edit command) •••.••...•.••••
BLOCKED (typed by editor) •....••••••.•••••.•.•••
(BO n) (edit command) ...........••••...•••••••••
BY (in REPLACE command) (in editor) •••••••••••••
CAN'T - AT TOP (typed by editor) .••••.•••.••••••
CAP (edi t command) ........•.•.•••••••••••••••.••
(CHANGE @ TO ... ) (edit command) ••••..•.•.••.••.
CUANGENAHE[ FN; FROM; TO] •....•••••••••••••••••••••
CL (e d i t comma nd ) . . . . . . . . . . . . • • • • . . . . . • • • • • • • • . •
commands that move parenthe:ses (in editor) ••••.•
(COMS xl ... xn) (edit command) •.•••••••.•.•••••
(COMSQ . corns) (edit command) •••••••••••••••••••
continuing an edit session •..•••••••••••••••••••
control-D
control-E
...................................... .
...................................... .
current expression (in editor) ••••••••••••••••••
DELETE (edit command) .....•..•••.•••••••••••••••
( DE LE TE . @) (ed i t command) ...•.•••••••••.••••••
DESTINATION IS INSIDE EXPRESSION BEING HOVED
(typed by editor) .......•••.•••.•••••••••••
OW (edit command) ................................ .
DWIHFLG (system variable/parameter) •••••••••••••
E (edi t command) .................................. .
(E x T) (edi t command) ..•...••••••••••••••••••••
(E x) (edit command) ...••.•.••••••••.•••••••••••
EOIT (typed by editor) .••.•.••••••••••••••••••••
edi t chain
...............
t
••••••••••••••••••••••
edit commands that search .......•••••.••.•••••.•
ed it commands that test .....••.•.•.••.••••••••••
edit macros ...................................... .
EDIT-SAVE (property name) ~ ...•••.•••••••••••.•.•
EOIT4E[PAT:X;CHANGEFLG] .....••....•.•••••••••••••
EOITCOMSA (editor variable/parameter) .••••••..••
EOITCOMSL (edi tor variable/I)arameter) ••••••••.••
EOITOEFAULT (in editor) ......•..•...•....•..••.•.
EOITE[EXPR;COHS;ATH] ...•. ~ ••••••••••..••.•••••••
EOITF[X] NL*
.............., .••••••••.•.••••..•••••
EOITFINDP[X;PAT;FlG] ....• ~ ••••••.•••••••••••••••
EOITFNS[X] NL •........•.•.••••••.•••••••••••••••
EOITFPAT[PAT;FLG] .•...•.•
~
editing compiled functions ••••••••••••••••••.•••
u ••••••••••••
IN[)EX.9.1
•••••••••
9.13,39-40
9.85-87
9.41
9.48
9.13,30"40
9.41
9.48
9.31
9:31
9.10.28
9.28
9.8,52
9.52
9.70
9.10,18-19
9.19
9.79
9.8,52
9.42
9.5,17
9.75
9.4'2
9.90
9.77
9.51-54
9.63
9.64
9.72-74
9.71
9.3
9.2,4,8.11-15,23
9.14,37,40,42
9.42
9.49
9.77
9.80,85"86
9.9,62
9.62
9.62
9.83
9.4,7.11~13,15,23
9.21-33
9.64
9.67-70
9.72
9.88
9.80,82
9.80-82
9.80-83
9.1,83,86-87
9.1,84-86
9.89
9.87-88
9.69
9.90
Page
Numbers
EOITL[L;COMS;ATM;MESS] .........•.•...••.........
EOITLO[L;COMS;MESS;EDITLFLG] ..........•..•.•.•..
EOITP[X] Nt* ...••.•......•.•••••••••.•••••••••••
EOITQUIETFLG (e~itor variable/parameter) •••.••.•
EDITRACEFN
...................................... .
EOITUSERFN
•...••.•..•
0
••••••••••••••••••••••••••
EOITV[EOITVX] Nt- ...•.•.••••••••••••••••••••••••
(EMBED @ IN ... ) (edit command) •.•••••••••••••••
errors (in editor)
..••.•.•••••••••••.•••••••••••
ESUBST[X;Y;Z;ERRORFLG;CHARFLG] ..••....••••.•.•••
( EXAM . x) (ed i t command) ••••.••••••••••••••••••
EXPR (property name) ........•....•.•••••.•••••••
(EXTRACT @1 from. @2) (edit cODlDand) •••••.•••••
F (edit command) .........••..•••.•••.•••••••••••
F pattern (edit command) ....••••••••••••••••..••
(F pattern N) (edit command) .•...•.•••••••.•••.•
(F pattern n) (n a number. edit command) ••.•••••
(F pattern T) (edit command) .•.•••.•••.•••••••••
(F pattern) (edit command) ••••••••••••••••••••••
(F= ... ) (edit command) ..•.......•••••.••••.••••
FOR (in INSERT command) (in editor) •••..••.•.•••
FROM (in EXTRACT command) (in editor) •••••••••••
(FS ... ) (edit command) ..•..••••••••••••••••••••
generalized NTH command (in editor) •••••••••••••
HERE (in edit command) ..... ~ ...•••••..••••••••.•
history list
................................... .
(I c xl ... xn) (edit command) .•.••..•.•.•..•.•.
(If x coms1 coms2) (edit command) •••.•••••..•.••
(IF x coms1) (edit command) .•.....•••.••.•..•..•
(If x) (edit command) .......•....••••••••••..•.•.
implementation of structure modification commands
IN
(in edito.r)
...........••...•.•••••.••.•.••.
(in EHBED command) (in editor) •••••••••••••••
(INSERT ... AFTER. @) (edit command) ••••••..•••
(INSERT ... BEFORE . @) (edit command) ..••.•••••
(INSERT ... FOR. @) (edit command) •••••••.•.•••
JOINC (edit command) ....•...••••••••••••••••••••
L-CASE[X;FLG] .....................•••.........•.
LASTAIL (editor variable/parameter) •••••••••••••
LASTVALUE (property name) .........••.••.••.•....
LASTWORO (system variable/parameter) ••••••••••••
(LC . @) (edit command) .....•....••...••••••..••
(LCL . @) (edit command) •.•..•••.•••.•••••••••.•
(LI n) (edit command) .....•..•••.••••.••••.•••••
lISPX
.......................................... .
(LO n) (edit command)
.....•...•...•..••••••.••.•
location specification (in editor) ••••••••..•••.
LOCATION UNCERTAIN (typed by editor) •••••.••.•••
LOWER (edit command) ....•..•••••••••••••••••••••
(LOWER x) (edit command) ...•.•••..••..•••.•••••.
(LP . corns) (edi t command) •.......•......•.•••.•
(LPQ . coms) (edit command) .••••.••••.•••..•••••
(H (c) (argl .•. argn) • corns) (edit command)
(M (c) arg .. corns) ..0' •.••••••••••••••••••••••••••
(H c . corns) (edit command) •••••••••••••••••••••
macros (in editor) •..•••••••••••••••••••••••••••
HARK (edt t conunand) ••.••••••••••.•••••••••••••••
9.83-84
9.84
9.1,85,87
9.22
9.90-91
9.80
9.1,85-86
9.48
9.3
9.89
9.66
9.85,88
9.46
9.6,25-26
9.25
9.26
9.26
9.26
9.27
9.27
9.41
9.46
9.27
9.32,52,60
9.42
9.73,78
9.62
9.65
9.65
9.64
9.37-39
9.48
9.41
9.41
9.41
9.76
9.74
9.16-17,25,84
9.72
9.85-86
9.30
9.30
9.8.53
9.62,73
9.8,53
9.28-29,64
9.17
9.74
9.75
9.65-66
9.66
9.68
9.68
9.67
9.67-70
9.34
Page
Numbers
(HARK a tom) (edi t conunand) ••••••••••••••••••••••
HARKLST (editor variable/parameter) •••••••••••••
HAXLEVEl (editor variable/parameter) ••••••••••••
HAXLOOP (editor variable/parameter) •••••••••••••
HAXLOOP EXCEEDED (typed by editor) ••••••••••••••
(HBD 01 ... em) (edit conunilnd) ••••••••••••••••••
(MOVE @1 TO com • @2) (edi 1~ command) •••••••••••
0
n (n a number, edit command)
••••••••••••••••••••
(N el •.. em) (edit command) ••••••••••••••••••••
(n e 1 ... em) (n a number, edt t command) •••
(n) (n a number ted! t commclnd)
•••••••••••••••
0
••••
0
••
NEWFILE?[NAME;VARSFLG] ....•••••.••••••••••••••••
NEX (edit command) ..••••.•••••
(NEX x) (edit command) ••.••••••• ~ •••••••••••••••
NIL (edit command) .•••••.•••••••••••••••••••••••
0
NOBIN[)
•••••••••••••• 0
••
.....•.......•.•.. '.•.••••••••••••••••.••••
NOT BLOCKED (typed by editor) •••••••••••••••••••
NOT CHANGED, 50 NOT UNSAVEO (typed by editor)
NOT EDITABLE (error message) ••••••••••••••••••••
NOTHING SAVED (typed by editor) •••••••••••••••••
(NTH n) (n a number, edit c:ommand) ••••••••••••••
(NTH x) (edit command) ••.) •••••••••••••••••••••••
NX (edt t command) •...•••., •••••••••••••••••••••••
(NX n) (n a number, edi t command) •••••••••
OCCURRENCES (typed by editor) •••••••••••••• ~ ••••
0
0'<
•••••
(edit cornrnand)
.......................
(edit command)
........................ .
(edi t command)
........................ .
P (edt t command)
••••••••
(P m n) (edi t command)
••
(P m) (edit conunand)
••••
(pattern .• @) (edit command)
•••••••••••••••••••
pattern match (in editor)
•••••••••••••••••••••••
PP (edi t command) •••••••..•••••••••••••••••••••••
ppliII: (edi t command)
••••••..•••••••••••••••••••••••
PPT (edit command)
.••••••.•••••••••••••••••••••••
PPV (edit command) ••••••..•••••••••••••••••••••••
prom p t c h a rae t e r
•••.•••••.•••••••••••••••••••••••
PROP (typed by cd! tor) •••.••••••••••••••••••••••
(R x y) (edi t command)
........................... .
(Rt x y) (edit command)
•
RAISE (edit command) ••••.•••••••••••••••••••••••
(RAISE X) (edit command) .••••••••
(RC x y) (edit command) •.•••••••••••••••••••••••
(Ret x y) (edit command)
••••••••••••••••••••••••
0
••••••••
(ORF ... )
(ORR ... )
t• • • • • • • • • • • • • • • • • • • • • • • •
II
•••••••••••••••••••••••
t• • • • • • • • • • • • • • • • • • • • • • • •
0
t·
••••••••••••••••••••••
0
0
••••••••••••••
REAOL INE[ LINE; LISPXFLG] .....•.••••••••••••••••.•
REPACK (edit command) •••••••••••••••••••••••••••
(REPACK @) (edit conunand) •••••••••••••••••••••••
(REPLACE @ WITH ... ) (edit command) •••••••••••••
RESETVAR[RESETX;RE5ETY;RESETZ] NL •.•.•••••.•••••
(RESE TVAR var form . corns) (ed! t cOlilDand) •••••••
(RI n m) (edi t command) •••••••••••••••••••••••••
(RO n) (edit command) •••••••••••••••••••••••••••
(5 var . @) (edit command)
•••
SAVE (edi t command) •••••••••••••••••••••••••••••
0
••••••••••••••••••
search algorithm (in editor)
••••••••••••••••••••
(SHOW. x) (edit command)
•••••••••••••••••••••••
INDEX.9.l
9.34
9.34,84
9.24,28
9.66
9.66
9.47
9.48
9.3.17
9.36
9.5,36
9.5,36
9.86
9.32
9.32
9.64,70
9.86
9.79
9.85
9.83,85
9.78
9.20
9 ..32-33
9.8,18-t9
9.19
9.65
9.71,76,83
9.27
9.66
9.2,60
9.60
9.60
9.33
9.21-23,88-89
9.2,60
9.61
9.61
9.61
9.2
9.85
9.7,57
9.59
9.74
9.75
9.59
9.59
9.81
9.75
9.76
9.42
9.77
9.77
9.8,53
9.8.53
9.36
9.72,74,83-84
9.23-25
9.66
Page
Numbers
spelling correction ....•..••••••••••.•••••••..••
(SPLITC x) (edit command) ..•.•...••••.•••••••.••
STOP (edit command) ....•...•.••.••...•.••••.••••
structur~ modification commands (in editor)
(SURROUND @ IN •.. ) (edit command) •..••••..•.•••
(SW n m) (edit command) .••••••••••••••••••.•••••
teletype
........... ............................. .
TEST (edit command) .••••••••••••.•••••••••••••••
THRU (edi t command) •.••.••.•..•••••••.•••.••••••
TO (edit command) .••••••••••••••••••••••••••••••
TTY: (edit command) ...••...••••..••••••.••••••••
TTY: (typed by editor) •.••••••••••••••••••••••••
U-CASE[ X]
.............••.•••••••••••••••••••••••
UNBLOCK (edit command) .•••.••.••••••••••••••••••
UNDO (edit command) ....•..••••••••••.••••.•••.••
undoing (in editor) ....••.••.••.••••••••••••••••
UNOOLST (editor variable/parameter) •••••••••••••
UNDONE (typed by editor) .•.•.•••••••••••••••••••
UNFIND (editor variable/parameter) ••••••••••••••
UNSAVEO (typed by editor) .••••••••••••••••••••••
UP (cdi t command) .......•.•.•.••••••••••••••••••
UPFINDFLG (editor variable/parameter) •••••••••••
USERMACROS (editor variable/parameter) ••.•..•••.
USERMACROS (.pret tydef command) .....•.•.•••.•.•••
USERWOROS (system variable/parameter) ••.••.••.••
WITH (in REPLACE command) (in editor) •.••••••
WITH (in SURROUND command) (in editor) .•••..•••.
(XTR . @) (edit command) .•.•••••••••.•••••••••••
o (edit conunand) .........•.•.•.•••••.•.•••••..••
! 0 (edi t comm
nchars[x]
or
< minus[nchars[x]] or ! corresponds to a character
in ! to the
If
!
righ~
is
of the character indicated by
not
a
string,
equivalent
m.
to
subs,tring[mkstring[x];n ;m], except substring does
not have to actually make the string if .! is a
litelrel atom. 6 For example,
substring[CA B C);4;6]-WB C·.
gnc[x]
Bet !ext £haracter of string!.
Returns the next
char'acter of the string, Cas an atom), and removes
the character from the string.
is the null string.
is made.
Returns NIL if .!
If! isn't a string, a string
Used for sequential access to characters
of a. string.
Note that if ! is a substring of I. gnc[x] does
not remove the character from I. i.e. pnc doesn't
physically change the string of characters. just
the pointer end the byte count. B
6---------------------------------~-------------------------------------------See string storage section that follows.
6
See string storage section that follows.
10.6
glc[x]
sets last !;,haracter of string!.
Above remarks
about pnc also supply to glc.
lambda nospread function.
Concatenates (copies
of) any number of strings.
The arguments are
transformed to strings if they aren' t
strings.
Value is the new string, e.g.
concat[ -ABC- ;OEF; -GHI-]
= -ABCOEFGHI-.
The value
of concat[l is the null string, --
rplstring[x;n;y]
Re!!ace
characters
character
negative.
n with
!
string
string l.
!
n may
beginning
at
be positive or
and l are converted to strings if
they aren't already.
(converted)!.
of
Characters are smashed into
Returns new!.
Error if there is
not enough room in ! for l' i.e. the new string
would be longer than the original.' Note that if !
is a substring of !. ! will also be modified by
the action of rplstring.
mkatom[x]
Creates an atom whose pname is the same as that of
the string ! or ,if ! isn't a string. the same as
that of mkstring[xl, e.g.
atom
X(AX ax ex).
If
mkatom[(A B C)l is the
atom
would
have
) 99
characters, causes an error, ATOM TOO LONG.
7-----------------------------------------------------------------------------If l was not a string, ! will already have been partially modified since
rplstring does not know whether l will 'fit' without actually attempting
the transfer.
10.7
Searching Strings
strpos is a function for searching one string looking for another.
Roughly it
corresponds to member, except that it returns a character position number
instead of a tail.
This number can then be given to substring or utilized in
other calls to strpos.
strpos[x;y;start;skip;~nchor;tail]
!
and I
are both strings
converted automatically).
(or else
they are
Searches I beginning at
cha."acter number start, (or else 1 if
sta~rt
is
NIL) and looks for a sequence of characters equal
to!.
If a match is round,
the corresponding
chal"acter position is returned,
otherwise NIL,
e.g., ,
strpos[-ABC-,-XYZABCDEF-]=4
strpos[-ABC·,·XYZABCDEF-;5]=NIl
strpos[·ABC·,·XYZABCDEFABC-;5]=10
ski)! can be used to specify a character in
~
that
with
the
matches any character in I, e.g.
strpos[·A&C'-;-XYZABCDEF·;Nll;&]=4
If anchor
chal~acters
is
T,
strpos
compares !
beginning at position start, or 1.
If
that comparison fails, strpos returns NIL without
seal~ching
any further down I.
Thus it can be used
to compare one string with some portion of another
string, e.g.
strpos[-ABC·;·XYZABCDEF·;NIl;NIl;T]=NIl
strpos[·ABC·;·XYZABCDEF·;4;NIL;Tl=4
10.8
Finally,
if tail is T.
the value returned by
strpos if successful is not the starting position
of the sequence of characters corresponding to !,
but the position of the first. charac ter after
that,
i.e.
starting point plus nchars[x] e.g.
strpos[-ABC-i-XYZABCOEFABC-;NIl;NIliNIliT]-7.
Note
that strpos[-A-;-A-;NIL;NIL;NIL;T]-2,
even
though -A- has only one character.
Example Problem
Given the strings !, l' and !, write a function
corresponding
to
that
portion
of
!
~
that will make a string
e.g.
and
between
Solution:
(FOO
[LAMBDA (X Y Z)
(AND (SETQ Y (STRPOS Y X NIL NIL NIL T»
(SETQ Z (STRPOS Z X V»~
(SUBSTRING X Y (SUB1 Z])
strposl[a;str;start;neg]
str
is
a
string
(or
else
automatically to a string),
characters or character codes. 8
it
!
is
is
converted
a
list
of
strposl searches
str beginning at character number start (or else 1
if .!1!.!::!=NIl) for one of the characters
in~.
If
one is found, strposl returns as its value the
8---------~------------------------------------------- -------------------------
If any element of a is a number, it is assumed to be a character code.
Otherwise, it is converted to a character code via chconl. Therefore, it
is more efficient to call strposl with! a list of character codes.
10.9
cor'responding character position, otherwise NIL.
E.gl.,
strposl[(A B C);-XYZBCO·]=4.
If
neg=T,
str'posl searches for a character not on !, e.g.,
strposl[(A B C); ·ABCOEF·:NIL;T]=4.
If ! is an array, it is treated as a bit table.
Thel
bits of (EL TAl) correspond to character
codes 0 to 43Q, of (ELT A 2) to codes 44Q to 107Q,
etc:.
Thus an array whose 'first element was 17Q
wOUild be equivalent to a list (400 410 420 430) or
(1_.
If
~
I I- I).
is not a bit table (array), strposl first converts it to a bit table using
makebittable described below.
If strposl is to be called frequently with the
same list of characters, a cons,iderable savings can be achieved by converting
the list to a bit table once, and then passing the bit table to
strpos~
as its
first argument.
makebittable[l:neg;a]
makes a bit table suitable for use by strposl.
andl neg are as for strposl.
!
If! is not an array
with at least 4 elements, makebittable will create
an array and return that as its value.
Otherwise
it uses (and changes) !.
Note:
if neg=T. strposl must call makebittable whether ! is a list or an
array.
To obtain bit table a/fficiency with neg=T, makebi ttable should be
called with neg=1, to construct the -inverted- table, and the resulting table
(array) should be given to strpc,sI with neg-NIL.
10.10
String Storage
A string is stored in 2 parts; the characters of the string, and a pOinter to
the characters.
The pointer, or 'string pointer', indicates the b,te at which
the string beg,ins and the length of the string.
storage.
a
It occupies one word of
The characters of the string are stored five characters to a word in
portion of the
INTERLISP address space devoted exclusively to storing
characters.
Since the internal pname of literal atoms also consists of a pOinter to the
beginning of a string of characters and a byte count, conversion between
literal atoms and strings does not require any additional storage for the
characters of the pname, although one cell is required for the string pointer. 9
When the conversion is done internally, e.g. as in substring,
strpos, or
strposl, no additional storage is required for using literal atoms instead of
strings.
The use of storage by the basic string functions is given below:
mkstring[x]
substring[x;n:m]
x string
no space
x literal atom
new pOinter
other
new characters and pointer
! string
new pointer
x literal atom
new pOinter
other
new characters and pointer
9-~---~--~---------------~---------------------------- -------------------------
Except when the string is to be smashed by rplstring. In this case, its
characters must be copied to avoid smashing the pname of the atom.
rplstring automatically performs this operation.
10.11
gnc[x] and glc[x]
x string
no space, pointer is modified
other
like mkstrina.
but doesn '·t make much
sense
args, any type
new
characters
for
whole
new
string, one new pointer
rplstring[x:n:y]
no new space unless characters are in
x string
(as
space
pname
mkstring[ atom])
in
of
result
which
case
1f
is
quietly copied to string space
10.3
x other
new pointer and characters
y any type
type of y doesn't matter
Array Functions
Space for arrays and compiled code are both allocated out of a common array
space.
. Arrays of pointers and unboxed numbers may be manipulated by the
following functions:
array[n:p:v]
This function allocates a block of n+Z words, of
which the first two are header information.
The
nex1; pin are cells which will contain unboxed
numbers, and are initialized to unboxed
last
n-p 2 0
ini1~ialized
avajLlable
storing
contain y.
an
poilllters) •
will
contain
pointers
with y, i.e., both £!!: and cdr are
for
ini1~ially
(i.EI.,
cells
o. . The
array
information,
If
~
is NIL,
containing
all
and
each
0 is used
INTERLISP
The value of array is the array, also
10.12
called an array pOinter.
If sufficient space is
not available for the array, a garbage collection
of array space, GC: 1, is initiated.
If this is
unsuccessful in obtaining sufficient space,
an
error is generated, ARRAYS FULL.
Array-pointers print as In, _here n is the octal representation 0/ the pointer.
Note that In _tll be read a$ a lit~ral atom. and not an array pointer.
arraysize[a]
Returns the size of array I.
Generates an error,
ARG NOT ARRAY, if I is not an array_
arrayp[x]
Value is ! if ! is an array pointer otherwise NIL.
No check
is made
to
ensure
that !
actually
addresses the beginning of an array.
elt[a.n]
Value
is
nth
element
of
the
array 1 10
elt
generates an error, ARG NOT ARRAY, if ! is not the
beginning of an array.l1
If n corresponds to the
unboxed region of !, the value of elt is the full
36 bit word, as a boxed integer.
If
n corresponds
to the potnter region of !, the value of elt is
the
seta[a;n:v]
~
half of the corresponding element.
sets the nth element of the array I_
Generates an
io------------~---------------~---~------------------- -------------------------
elt[a;l] is the first element of the array (actually corresponds to the 3rd
cell because of the 2 word header).
11
arrayp is true for pointers into the middle of arrays, but elt and seta
must be given a pointer to the beginning of an array, i.e.,~ value of
array.
10.13
error, ARG NOT ARRAY,
of an array.
If
~
i f ! is not the beginning
corresponds to the unboxed
regjion of !, y must be a number, and is unboxed
and stored as a full 36 bit word into the nth
elenlent of!.
If!! corresponds to the pointer
region of !, y replaces the £!! half of the nth
The value of seta is y.
elenlent.
Note that seta and el t are a llDall.!; i""erse operations.
eltd[a;n]
samel as 81 t for unboxed region of a, but returns
cdr half of nth element, if.!! corresponds to the
pointer regionlOf !.
setd[a;n;v]
samel as seta for unboxed region of a, but sets cdr
half' of nth element, if n corresponds to tiii
poinlter region of!. The value of ~ is .!.
In ,other words, eltd and setd are! always inverse operations.
10.4
Storage Functions
reclaim[n]
Initiates a garbage collection of type n. Value
of r~eclaim is number of words available "(for that
typi) after the ~ollection.
Garbage collections. IDhether inuoled directlll bll the user or indirectlll bll need
Jor storage. do not confine their actil/itll solelll to the data tllpe lor which
thell were called. but automaticallll collect some or all 0/ the other tllpes (see
Section 8).
ntyp[x]
Value
is
type
number.
for
the
data
type
of
INTERLISP pointer !, e.g. ntyp[(A • B)] is 8, the
type number for lists..
Thus GC: 8 indicates a
garbage collection of list words.
10.14
type
number
arrays, compiled code
stack positionsi
list words·
atoms
.
floating point numbers
large integers
small integers
string pointers
pname storage
string storage
1
2
8
12
16
18
20
24
28
30
typep[x;n]
eq[ntyp[x];n]
gcgag[message]
message is a string or atom to be printed (using
print) wherever a garbage collection is begun.
If
message=T, its 'standard setting, GC: is printed,
followed by the type number.
When the garbage.
collection is c!:omplete. two numbers are printed
the number of words collected for that type, and
the total number or words available for that type,
i.e. allocated :but not necessarily currently in
use (see --,
minfs ~elow).
Example:
"'RECLAIM( 18)
GC: 18
511, 3071 FREE WORDS
3071
"'RECLAIM(12)
GC: 12.
1020, 1020 FREE WORDS
1020
If message=NIL, no garbage collection message is
printed, either on entering or leaving the garbage
collector.
Value of i£H!i is old setting.
10.18
minfs[njtyp]
8ets the minimum amount of free storage which will
be maintained by the garbage collector for data
types of type number!IR.
If,p after any garbage
collection tor that type, fewer than II free words
are pre$ent. sufficient storage will be added (in
512 word chunks) to
rai~e
the level to
If !IR=NIl, 8 is used, i.e.
th~
n.
minfs.refers to
lis·t words.
If
l~.NIl,
minfs returns the current !!!!!!f! setting
for the corresponding type.
A minfs
setting can also be changed dynamically,
even during a garbage
collection, by typing control-8 followed by a number, followed by a perio,d. 12
If the control-S was typed durirng a garbage collection, the number is the new
minfs setting for the type beinlg collected, otherwise for type 8, i.e. list
words.
Note, A garbage collection oJ a 'related' tupe mall also cause more storage to
be assigned to that tllpe. See discussion oJ garbage collector algorithm.
Section 8.
storage[flg]
Prints amount ot storage (by type number) used by
and assigned to the user, e.g.
12----------------------------------------------------------------------------When the control-S is typed, INTERLISP immediately clears and saves the
input buffer, rings the bell, and waits for input, which is terminated by
any non-number.
The input buffer is then restored, and the program
continues. If the input was terminated by other than a period, it is
ignored.
10.16
"STORAGE()
TYPE USED
ASSIGNED
1
8
12
80072
7970
7032
87552
16
0
18
24
28
30
1124
118
4226
573
4608
1024
SUM
101115
113664
9216
7680
512
2560
512
If f1g=T. includes storage used by and assigned to
the system.
gctrp[n]
Value is NIL.
sarbage£ollection
tra~.
Causes
a
(simulated)
control-H interrupt when the number of free list
words (type 8) remaining equals !!,
garbage collection would occur in
The
message
GCTRP
interrupt (Section
occurs.
Note
is
16)
that
by
i.e. when a
n more
conses.
the
function
printed,
is called.
and a
advising
(Section
break
19)
interrupt the user can program the handling of a
1lillI!. instead of going into a break. 18
Value of 1lillI!. is its last setting.
gctrp[ -1] will
I
disable' a previous Qctrp since
there are never -1 free list words.
qctrp
is
initialized this way.
ii----------------------------------------------------------------------------For Ilf!!:..2 interrupts, interrupt is called with intype (its third argument)
equal to 3. If the user does not want to go into a break, the advice
should still allow interrupt to be entered, but first set intype to -1.
This will cause interrupt to -quietly· go away by calling the function that
was interrupted. The advice should not exit interrupt via return, as in
this case the function that was about to be called when the interrupt
occurred would not be called.
10.17
gct,rp[] returns number of list words left, i.e.
nun~er
of
conses
until
next
type
8
garbage
collection, see Section 21.
conscount[n]
conscount[ ]
returns
INT'ERLISP started up.
number
of
conses
since
If !! is not NIL,
resets
conscount to !!.
closer[a.x]
Stores ! into memory location ! .
Both
~
and !!
must be numbers.
openr[a]
Value is the number in memory location .!,
boxed.
10.18
i. e.
Index for Section 10
Page
Numbers
·................................ .
·............................. .
·............................... .
AOOOn (gensym)
ARG NOT ARRAY (error message)
ARRAY[N;P;V] SUBR
array functions
array header
ARRAYP[X] SUBR
ARRAYS FULL (error message)
ARRAYSIZE[A]
ATOM TOO LONG (error message)
bell (typed by system)
CHARACTER[N] SUBR
character atoms
character codes ·
CHCON[X;FLG] SUBR
CHCON1[X] SUBR
ClOSER[A;X] SUBR
compiled code
CONCAT[Xl;X2: .•• ;Xn] SUBRCONSCOUNT[N] SUBR
control-H
control-S
DCHCON[X;SCRATCHlIST;FlG]
DUNPACK[X;SCRATCHLIST;FLG]
ElT[A;N] SUBR
ELTO[A;N] SUBR
FCHARACTER[N] SUBR
garbage collection
GC:, (typed by system) •••••••••••••••••••••••••••
GC: ,1 (typed by system)
GC: 8 (typed by system)
GCGAG[MESSAGE] SUBR
GCTRP[N] SUBR
GENNUM (system variable/parameter)
GENSYM[CHAR]
GlC[X] SUBR
GNC[X] SUBR
input buffer ·
INTERRUPT[INTFN.INTARGS;INTYPE]
literal atoms
MAKEBITTABLE[L;NEG;A]
MAPATOMS[FN] SUBR
MINFS[N;TYP] StlBR
MKATOM[X] SUBR
MKSTRING[X] SUBR
NCHARS[X] SUBR
NTHCHAR[X;N] SUBR
NTYP[X] SUBR
null string
OPENR[A] SUBR
PACK[X] SUBR
PACKC[X] SUBR
pnames
prin2-pnames
print name
RAOIX[N] SUBR
RECLAIM[N] SUBR
·.................................. .
.....................
·.................................. .
...........................
·
.............................
·...............................
.
............................... .
·............................. ..
·................................
................................
·............................... .
·............................. .
.......................................
.......................................
·................................ .
..............................
..............................
.........................
·................................. .
·.................................. .
.....................................
.....................................
..................................
.
.................
·................................. .
·............................. .
·............................. .
·................................
.
................................
·..................... ............ .
·........... .................. ..
·..................................
·................................. .
··..................................
.
.................................
.
..........................................
·................................... .
......................................
·................................. .
·............................... .
'
'
INDEX.10.1
10.5
10.13-14
10.12
10.12-14
10.12
10.13
10.13
10.13
10.2,7
10.16
10.4
10.2
10.4
10.4
10.4
10.18
10.12·
10.7,12
10.18
10.17
10.16
10.4
10.3
10.13
10.14
10.4
10.13-18
10.15
10.13
10.14
10.15
10.17
10.5
10.4-5
10.7,12
10.6,12
10.16
10.17
10.11
10.10
10.5
10.16
10.7
10.5,11
10.3
10.3
10.14
10.6-7
10.18
10.2
10.4
10.1-4,11
10.1,3-4
10.1
10.1
10.14
Page
Numbers
RPlSTRING[X;N;Y] SUBR
RSTRING[] SUBR
searching strings
SETA[A;N;V]
SETO[A;N;V]
STORAGE[FlG]
STREQUAl[X;Y]
string characters
string functions
string pointers
string storage
STRINGP[X] SUBR
STRPOS[X;V;START;SKIP;ANCHOR;TAIL]
STRPOSl[A;STR;START;NEG]
SUBSTRING[X:N;H] SUBR
type numbers
TVPEP[X;N]
unboxed numbers (in arrays)
UNPACK[X;FLG] SUBR
I (followed by a number)
... ................................. .
....................................
,
.....................
IND:EX.I0 .2
10.7,12
10.5
10.8-10
10.13
10.14
10.16
10.5
10.11
10.5-10
10.6,11
10.11-12
10.5
10.8-9
10.9-10
10.6,11
10.14
10.15
10.12
10.2-3
10.13
SECTION 11
FUNCTIONS WITH FUNCTIONAL ARGUMENTS
As in' all LISP 1.5 Systems, arguments can be passed which can then be used as
functions.
However, since £!! of a form is neuer evaluated,
!22!l
or· apply·
must be used to call the function specified by the value of the functional
argument •.
Functions which use functional arguments should use variables with obscure
names to avoid possible conflict with variables that are used by the functional
argument.
for example, all system functions standardly use variable names
consisti,ng of the function name concatenated with! or fn, e.g. mapx.
Note
that by specifying the free variables used in a functional argument as the
second argument to function, thereby using the INTERLISP FUNARG feature, the
user can be sure of no clash.
function[x;y]
If l=NIL, the value of
is an nlambda function.
function is identical to quote, for example,
(HAPC LST (FUNCTION PRINT»
will cause mapc to be
called with two arguments the value of 1st and
PRINT. Similarly,
(HAPCAR LST (FUNCTION(LAHBDA(Z) (LIST (CAR Z»»)
will cause mapcar to be called with the value of
1st
and
(LAMBDA (Z) (LIST (CAR Z»).
compiled, function will cause code to be
for !; guote will not.
11.1
Thus
When
~omplled
(MAPCAR LST (QUOTE (LAMBDA
to be called with
therefore
will cause mapcar
the value of 1st
expression (LAMBDA --).
will
--»)
and
The functional
still
be
the
argument
interpreted.
The
corresponding expression using function will cause
a dummy function to be created with definition
(LAMBDA --)_ and then compiled.
mapcar would then
be Icalled with the value of 1st and the name of
the dummy function.
See Section 18.
If l is not NIL_ it is a list of variables that
are (presumably) used freely by!.
In this case,
the value of function is an expression of the form
(FUMARG x array),
where
variable
for
Funa~
map[mapx;mapfnl;mapfriZ]
If
bindings
array
those
contains
variables
on
~.
is described on page 11.5-7.
~lapfnZ
is NIL, map applies the function mapfnt
to :.uccessive tails of the list mapx.
first
the
it
computes
mapfnl[mapx],
That is,
then
mapf'nl[cdr[mapx]]. etc., until mapx is exhausted. 1
If
mapfnZ
is
provided,
mapfnZ[mapx]
and
is
used
instead of cdr[mapx] for the next call for mapfnt_
e.g., if mapfnZ were cddr, alternate elements of
the list would be skipped.
The value of map is NIL. map compiles open.
i--------~--------------------·-------·-·------------- ------------~~-------~--~
i.e."
becomes a non-list.
11.2
mapc[mapx;mapfnl;mapfn2]
Identical to map. except that mapfnl[car[mapx]] is
computed
each
at
instead
iteration
of
mapfnl[mapx]. i.e., mapc works on elements, map on
tails.
The value of mapc is NIL. mapc compiles
open.
maplist[mapx;mapfnl ;mapfn2] successively computes the same values that map
would compute; and returns a list consisting of
those values. maplist compiles open.
computes the same values that mapc would compute,
mapcar[mapx;mapfnl:mapfn2]
and returns a list consisting of those values,
e.g. mapcar[x;FNTYP] is a list of fntyps for each
element on!.
mapcar compiles open.
Computes the same values as map and maplist but
mapcon[mapx;mapfnl :mapfn2]
nconcs these values to form a list which
it
returns. mapcon compiles open.
mapconc[mapx;mapfnl:mapfn2] Computes the same values as mapc and mapcar, but
nconcsthe values to form a list which it returns.
mapconc compiles open.
Note that mapcar creates a new list which is a mapping of the old list in that
each element of the new list is the result of applying a function to the
corresponding element on the original list.
mapconc is used when there are a
variable number of elements (including none) to be inserted at each iteration,
e.g.
mapconc[X:(LAMBDA (Y) (AND Y (LIST
V»~)]
will make a list consisting of !
with all NILs removed, mapconc[X;(LAHBDA (Y) (AND (LISTP Y)
linear
list
consisting
of
all
the
11.3
lists
on
!,
e.g.
V»~]
if
will make a
applied
to
«A B) C (0 E F) (G) H I) will yield (A B 0 E F G)~2
subset[mapxjmapfnl ;mapfn2J
applies mapfnl to elements of mapx and returns a
list of those elements for which this application
is non-NIL, e.g.,
subset[(A B 3 C 4);NUMBERP]
= (3
4).
map'fn2 plays the same role as' wi th map, mapc, et
ale
map2c[mapx;mapy;mapfnl,mapfnZ]
subset compiles open.
Identical to mapc except mapfnl is a function
of two arguments, and mapfn1[car[mapx]:car[mapy]l
is computed at each interation. 3 Terminates when
etther mapx or
map2car[mapx;mapy;mapfnl;mapfn2]
~
Identical
func:tion
to
of
are exhausted.
mapcar
two
except
mapfn1
is
a
and
arguments
mapfnl[car[mapx];car[mapy]] is used to assemble
the new list.
Terminates when either mapx or m!2l
is ttxhausted.
Note:
CLISP (Section 23) provides a more general and complete facility for
expressing iterative statements, e.g.
(NUMBERP (CAR X»
(FOR X IN Y COLLECT (CAOR
X)
WHEN
UNTIL (NULL X»).
2--------------------------------'---------------------------------------------Note that since !!l.i!pconc uses !!.£Q.!!£ to string the corresponding lists
together, in this example, 'the original list will be clobbered, i.e. it
would now be «A B 0 E f G) C (0 E F G) (G) H I). If this is an undesirable
side effect, the functional argument to mapconc should return instead 8 top
level copy, e.g. in this case, use (AND (lISTP Y) (APPEND V»~.
a
mapfn2 is still a function clfone argument, and is applied twice on each
iteration; mapfn2[mapx] gives the new mapx, mapfnZ[mapy] the new~. cdr
is used if mapfn2 is not supplied, i.e., 1s NIL.
11.4
maprint[lst:file;left:right;sepiPfn:lispxprintflg]
is a ge·nerel printing function.
It cycles through
1st applying pfn (or print if pfn not given) to
each element of 1st.
Between each application,
maprint performs prinl of sep, or • • if sep=NIL.
If left is given, it is printed (using print)
initially; if right is given it is printed (using
prinl)
at the end.
,
For example, maprint[x;NIL;X(;X)] is equivalent to
prin1 for lists.
To print a list with commas
between each element and a final '.' one could use
maprint[x;T;NIL;X.;%,].
If lispxprintflg • T, lispxprinl is used for prinl
(see Section 22).
Mapdl,searchpdl
See Section 12.
mapatoms
See Section 5.
every, some, notevery, notany
See Section 5.
Funarg
function is a function of two arguments, 2f' a function. and I
variables used freely by!.
a list of
If I is not NIL, the ualue of function is an
expression of the form (FUNARG x array), where array contains the bindings of
the variables on l at the time the call to function was evaluated.
not a function itself.
Like LAPlBDA and NLAHBDA.
funarg is
it has meaning and
is
specially recognized by INTERLISP only in the context of applying a function to
arguments.
In other words, the expression (FUNARG x array) 15 used exactly
11.5
like a function. 4 When a funarg is applied, the stack is modified so that th~
bindings contained in the arra3' will be in rorce when !, the runction.
1s
called. 6
For example, suppose a program wished to compute (FOO X (FUNCTION FIE», and
fie used land! as free variabJles.
If foorebound land z, fie would obtain
the rebound values when it was applied from inside of foo.
(FOO X (FUNCTION FIE (Y Z»),
instead
foo·
would
By evaluating
with
called
be
(FUNARG FIE array) as its second/argument, where arral contained the bindings
of
~.
and! (at the time foo was c:alled).
Thus when fie was applied from inside
of foo, it would 'see' the original values of land !.
However,
funarg
variables.
computation,
~Iust
is more than
a way of circumventing the clashing of
For examp.le, a funarQ expression can be returned as the value of a
and
then
used
'hlgher up',
e.g.,
when
the
variables contained in array: werli! no longer on the stack.
function
array,
bindings
of
the
Furthermore, if the
in a funarg expression .sets any of the variables contained in the
the array itself (and only the array) w1ll be changed.
. For example,
suppose foo is defined as
(LAMBDA (LST FN) (PROG (Y Z) (SElQ Y 8c) (SETQ Z 8c) ••• (HAPC LIST FN) ••• »
and (FOO X (FUNCTION FIE (Y Z» )is evaluated.
the mapc in foo) changes
~
If one application of fie (by
and !, then the next application of fie will obtain
the changed va lues of land ! retsu 1ting from the previous appl ica tion of fie,
since both applications of fie come from the exact same funarg object, and
hence use the exact same array.
The bindings of land! bound inside of foo,
and the bindings of 1.. and ! abofJe foo would not be affected.
In other. words,
4-----------------------------------------------------------------------------LAMBDA, NLAMBDA, and FUNARG expressions are sometimes called • function
objects' to distinguish them from functions, i.e., literal atoms which have
f~nction definitions.
6
The implementation of funarg is described in Section 12.
11.6
the variable bindings contained in array are a part of the function object,
i.e., the funarg carries its environment with it.
Thus by creating. a funarg expression with function, a program can create a
function object which has updateable binding( s) associated with the object
which last between calls to it, but are only accessible through that instance
of
the
maintain
function.
two
For example,
different
using the funarg device,
a
program could
instances of the same random number generator
in
different states, and run them independently.
Example
If foo is defined as (LAMBDA (X) (CONO «ZEROP A) X) (T (MINUS X») and fie as
(LAMBDA NIL (PROG (A) (SETQ A 2) (RETURN (FUNCTION FOO»». then if we perform
(SETQ A 0), (SETQ FUM (FIE»,
the value of f!!!!! is FOO,
and
the
value
of
(APPLY* FUM 3) is 3, because the value of A at the time faa is called is O.
However if fie were defined instead as
(LAMBDA NIL (PROG (A) (SETQ A Z) (RETURN (FUNC.TION FOO (A»»),
the
value
of
fum would be (FUNARG FOO array) and so the value of (APPLY* FUM 3) would be -3,
because the value of A seen by foo is the value A had when the funarg was
created inside of fie, i.e. 2.
11.7
Index for Section 11
Page
Numbers
APPLY[FN;ARGS] SUBR .......•••••.••••••.••••.••.•
APPLY*[FN;ARG1; ... ;ARGn] SUBR* ••••••••••••••.•••
CLISP ........................................... .
FUNARG .......................................... .
FUNCTION[EXP;VLIST] NL
•....••.•••••••••••••.••••
objects ..•.•..•.. , ••.•••••••••••••••••
fune tiona 1 argumen ts ....•.••••••••••••••••••••••
func~tion
0
••
MAP[ MAPX; MAPFN 1 ; MAPFN2 ] .. 0' • • • • • • • • • • • • • • • • • • • • • •
MAP2C[MAPX;MAPV;MAPFN1;MAPFNZ] .•••••••••••••••••
MAP2CAR[MAPX;MAPY;MAPFNl;MAPFN2] •. ~ •••••.•.•.•••
MAPC[MAPX;MAPFN1;MAPFN2]
MAPCAR[MAPX;MAPFN1;MAPFN2] .•.••.•••••••••....•••
MAPCON[MAPX;MAPFN1;MAPFN2] ...•.••.•.•..•.•...•••
MAPCONC[MAPX;MAPFN1;MAPFN2] •..•••••.•••••.••••••
MAPLIST[MAPX;MAPFN1;MAPFN2] ~ .••.•.••..••.•.•...•
MAPRINT[LST;FILE;LEFT;RIGHT;SEP;PFN;LSPXPRNTFLG] ••
SUBSET[MAPX;MAPFNl;MAPFNZ] ••.••••••.•••••••••.••
variable bindings .•••••••.••••••••••••••••••••••
.Q
••••••••••••••••••••••
INDIEX .11.1
11.1
11 • 1
11.4
11.1-2,5-7
11.1-2,5,7
11.6
11. 1
11.2
11.4
11.4
11.3
11.3
11.3
11.3
11.3
11.5
11.4
11.5-7
SECTION 12
VARIABLE BINDINGS AND PUSH DOWN LIST FUNCTIONS
A number of schemes have been used in different implementations of LISP tor
storing the values of variables.
These include:
1.
Storing values on an association list paired with the variable names.
2.
Storing values on the property list of the atom which is the name or
the.variable.
3.
Storing values in a special value cell associated with the atom name,
putting old values on a pushdown list, and restoring these values when
exiting from a function.
4.
Storing values on a pushdown list.
The first three schemes all have the property that values ar. scattered
throughout list structure space, and, in general, in a paging environment would
require references to many pages to determine the value of a variable.
would be very undesirable in our system.
This
In order to avoid this scattering,
and possibly excessive druM references, we utilize a variation on the fourth
standard scheme, usually only used for transmitting values of arguments to
compiled functions; that is, we place these values on the pushdown list. 1 But
12.1
since we use an interpreter as WEill as a compiler, the variable names must also
be kept.
The pushdown list thus contains pairs, each consisting of a variable
name and its value.
Each pair occupies one word or •slot • on the pushdown
1 ist, with the name in the left; half, 1.e. cdr, and the value 1n the right
half, i.e. car.
The interpreter gets the value of a variable by searching back
up the pushdown list looking for a· 'slot' for which cdr 1s the name of the
variable.
car is then its value.
One advantage of this scheme is that the current top of the pushdown stack is
usually in core, and thus drum references are rarely required to find the value
of a variable.
Free variables work automatically in a way similar to the
association list scheme.
An additional advantage of this s.cheme is that it is completely compatible with
compiled functions which pick up their arguments on the pushdown list from
known positions, instead of doing a search.
-
To keep complete compatibility.
,
our compiled functions put the rliames of their arguments on the pushdown list,
although they do not use them to reference variables.
Thus, free variables can
be used between compiled and interpreted functions with no special declarations
necessary.
fo~
The names on the pushdown list are also very useful in debugging,
they make possible a comple'te symbolic back trace in case of error.
Thus
this technique, for a small extra overhead, minimizes drum references, provides
symbolic debugging information, and allows completely free mixing of compiled
and interpreted routines.
There are three pushdown lists used in INTERLISP: the first is called the
parameter pushdown list. and contains pairs of variable names and values t and
temporary storage of pointers; tille second is called the control pushdown list,
and contains function returns and other control information; and the third is
called the number stack and is used for storing temporary partial results of
numeric operations.
12.2
However, it is more convenient for the use~ to consider the push-down list as a
single "list" containing the names of functions that have been entered but. not
yet eXited.
and the names and values of the corresponding variables.
The
multiplicity of pushdown lists in the actual implementation is for efficiency
of operation only.
The Push-Down List and the Interpreter
In addition to the names and values of arguments for functions. information
regarding partially-evaluated expressions is kept on the push-down list.
For
example, consider the following definition of the function, fact (intentionally
faulty) :
(FACT
[LAMBDA (N)
(CONO
«ZEROP N)
L)
(T (ITIMES N (FACT (SUBI N])
In evaluating the form (FACT 1), as soon as fact is entered, the interpreter
begins evaluating the implicit
~
following the LAMBDA (see Section 4).
first function entered in this process is cond.
list of clauses.
cond begins to process its
After calling zerop and getting a NIL value, cond proceeds to
the next clause and evaluates T. Since T is true,
impliCit
This
~
The
the evaluation of the
that is the consequent of the T clause is begun (see Section 4).
requires calling the function itimes.
called, its arguments must be evaluated.
searching the stack for
th~
However before itimes can be
The first argument is evaluated by
last binding of N; the second involves a recursive
call to fact, and another implicit
~,
etc.
Note that at each stage of this process, some portion of an expression has been
evaluated, and another is awaiting evaluation.
12.3
The output below illustrates
this by showing the state of the push-down list at the point in the computation
of (FACT 1) when the unbound atoDIi L is reached •
.. FACT(I)
U.S.A.
(L BROKEN)
:BTV!
-FORM* (BREAKI L T L NIL 134047)
10 (L)
10 «(ZEROP N) L) (T (ITIHES N (FACT (SUBI N»»)
1
CONO
*FORM* (CONO «ZEROP N) L) (T (ITIHES N (FACT (SUBl N»»)
10 «CONO «ZEROP N) L) (T (ll'IHES N (FACT (SUBl N»»»
2
N 0
FACT
*FORM* (FACT (SUBI N»
#2 ITIHES
10 «FACT (SUBI N»)
3
#0 1
4
*FORM* (ITIHES N (FACT (SUBI N»)
10 « ITIHES N (FACT (SUB1 N»»
5
10 «(ZEROP N) L) (T (ITIHES N (FACT (SUBl N»»)
6
*FORM* (CONO «ZEROP N) L) (T (ITIHES N (FACT (SUBI N»»)
10 (CONO «ZEROP N) L) (T (ITIHES N (FACT (SUBl N»»»
7
CONO
N1
FACT
Internal calls to eval, e.g., from cond and the interpreter, are marked on the
push-down list by a special mark called an oval-blip.
by
the
appearance of (VAG 64)
position, for that slot.
in the left-half,
eval-blips are indicated
i.e.
the variable name
They are printed by the backtrace as *FORM*. The
genealogy of *FORM*'s is thus a history of the computation.
Other temporary
information is frequently recorded on the push-down list in slots for which the
'variable name I
is
(VAG 0),
which prints as 10.
In this
example,
this
information consists of (1) the tail of a list of cond clauses, (2) the tail of
an implicit J!!:QIl!!. i.e., the de,'inition ot fact, (3) the tail of an argument
12.4
list, (4) the value of a previously Qvaluated argument, (5) the tail of a cond
clause whose predicate evaluated to true, and (6) and (7) same as (1) and (2).
Note that a function is not actually entered and does not appear on the stack,
until its arguments have been evaluated. 2 Also note that the 10 'bindings'
comprise the actual working storage.
In other words, in the above example, if
a (lower) function changed the value of the binding at (1) (not recommended)
the cond would continue interpreting the new binding as a list of
~
clauses.
Similarly, if (4) were changed, the new value would be given to itimes as its
first argument after its second argument had been evaluated. and itimes was
actually called.
The Pushdown List and Compiled Functions
Calls to compiled functions, and the bindings of their arguments. i. e. names
and values, are handled in the same way as ,for interpreted functions (hence the
compatibility between interpreted and compiled functions).
However, compiled
functions treat free variables in a special way that interpreted functions do
not.
Interpreted functions "look up" free variables when the variable is
encountered, and may look up the same variable many times. However, compiled
functions look up each free variable only once. 3 Whenever a compiled function
is entered, the pushdown list is scanned and the most recent binding for each
free variable used in the function is found (or if there is no binding, the
value cell is obtained) and stored in the right half of a slot on the stack (an
unboxed 0 is stored in the left half to distingUish this
'binding'
from
2~----------------~----------------------------------------------------~~------
except for functions which do not have their arguments evaluated (although
they themselves may call eval, e.g. cond).
8
A list of all free variables is generated at compile time, and is in fact
obtainable from the compiled definition. See Section 18.
12.5
ordinary bindings).
Thus, following the bindings of their arguments, compiled
functions store on the pushdown list pointers to the bindings for each (ree
variable used in the function.
In addi tion to the pointers tOI free variable bindings, compiled functions
differ
from
variables
t
interpreted
i. e.
J!!:.Q.Il!
functions
in
and open la.mbdas.
the way they
treat
locally
bound
Whereas in interpreted functions progs
and open lambdas are called in the ordinary way as functions, in compilation,
progs and open lambdas disappear, although the variables bound by them are
stored on the stack in the conventional manner so that functions called from
inside them can reference the variables.
argum~nts
following the
pointers (if any).
These variables appear on the stack
to the compiled function (if any) and the (ree variable
The only way to determine dynamically what variables are
bound locally by a compiled function is to search the stack from the first slot
the la.st argument to the 1:unction (which can be found with stknargs and
beyond
stkarg described below), to the slot corresponding to the Itr.st argument of the
next function.
Any slots
encoun1~ered
that contain literal atoms in their left
half are local bindings.
Pushdown List Functions
NOTE:
Unless otherwise stated, for all pushdown list functions,
position on the control stack.
(STKPOS
pos
1)
is used.
pos is a
If pos is a literal atom other than NIL,
In this case, if pos is not found, i.e., stkpos
returns NIL, an ILLEGAL STACK ARG error is generated.
stkpos[fn;n;pos]
Searlches the control stack starting at pos for the
~th
occurrence of fn.
12.6
Returns
control
stack
position of that fn if found,4 els.NIL. If ~ is
po.itive, searches backward (normal usage).
is negative,
searches forward,
control stack.
i.e.,
If
n
down the
For eXUlple, stkpos[FOO;-2;FIE]
finds second call to FOO after (below) the last
call to FIE. If !!. is NIL, 1 is used. 'If pos is
NIL, the search starts at the current position.
stkpos[] gives the current position.
stknth[n,pos]
Value is the stack position (control stack) of the
!!th function call relative to position pos.
If
> 0,
and the current position is assumed for n < 0,
pos is NIL, the top of stack is assumed for n
i.e.,
stknth[-l]
is
the
call
before
stknth,
stknth[1] is the call to evalgt at the top level.
Value of stknth is NIL if there is no such call e.g., stknth[10000] or stknth[-10;stknth[5]].
fstknth[n;pos]
version of stknth that compiles open.
stkname[pos]
Value is the name of the function at control stack
posi tion pos.
In this case, pos must be a real
stack position, not an atom.
In summary, stkpos converts. function names to stack positions, stknth converts
numbers to stack positions, and stkname converts positions to function names.
4--------~-----~·------------------------------------------------------~-----~-
A staek position is·a pointer to the ~orresponding slot on the control or
parameter stack, i.e., the address of that cell. It prints as an unboxed
number, 8.g.,.132002, and its type is 2 (Section 10).
12.7
Information about the variables bound at a· particular function call can be
obtained using the following func:tions.:
stknargs[pos]
Value is the number of ar:-guments bound by the
func:tion at position pOSe
stkarg[n;pos]
Value is a pOinter to the !!.th argument (named or
not)I 6 of the function at position pos, i.e., the
value is a parameter stack position.
~
of this
pointer gives the value of the binding, cdr the
namE~.
!l=1 corresponds to the first argument at
pos .
!! can be 0 or negative, i.e., stkarg[OjFOO]
is
pointer to the slot immediately before the
IS
fir!.t
argument
to FOO,
5tkarg[ -1 .FOO]
the
one
before that, etc.
fstkarg[n;pos]
ver$ion of stkars that compiles open.
Note that the user can change (set) the value of a particular binding by
performing an rplaca on the value of stkarA.
Similarly, rplacd changes (sets)
the name.
The value of stkarg is a posit:lon (slot) on the parameter stack.
currently
no
analogue
to
stknth
for
the
parameter stack.
There is
However,
the
parameter stack is a contiguous block of memory, so to obtain the slot previous
to a given slot, perform vag[subi[loc[slot]]]; to obtain the next slot perform
vag[addl[loc[slot]]]. i.e.
6--~------------~--~-~----------~---------------------------~------------------
Subrs do not store the names of their arguments.
12.8
.
stkarg[2;pos] • vag[.dd1[loc[stk.rg[1;pos]]]].~
As an example of the use of stknargs and stkarg:
variables[pos]
returns list of variables bound at
pOSe
can be defined by:
(VARIABLES
[LAMBDA (POS)
(PROG (N l)
(SETQ N (STkNARGS POS»
LP (COND
«ZEROP N)
(RETURN L»)
(SETQ L (CONS (CDR (STKARG N POS»
l»
(SETQ N (SUBt N»
(GO lP])
The counterpart of variables is also available.
stkargs[pos]
Returns list of values of variables bound at
pOSe
The next three functions, sttscan, evalv, and stkeval all involve searching the
parameter pushdown stack.
For all three functions, pos may be a position on
the control stack, i.e., a value of stkpos or stknth. 7 In this case, the ,search
starts at stkarg[stknargs[pos]jPos] i.e., it will include the arguments to the
function at pos but not any locally bound, variables.
pos may also be a
posi tion on the parameter stack, in which case the search starts with, and
includes that position.
Finally, pos can be NIL, in which case the search
starts with the current position on the parameter stack.
6----------~--------------------------------------------------~-----------~---See Section 13 for discussion of vag and loco
7
or a function name, which is equivalent
earlier.
t~
stkpos[pos;l] , as described
stkscan[var;pos]
Sear-ches backward on the parameter stack from' pos
for a binding of yare
binding
if
found,
position, otherwise
Value is the slot for that
i.e.,
y!!:
a
parameter
stack
itself (so that in the
casu of literal atoms, £!!: of stkscan is always
the value of !!!).
evalv[var,pos]
car[ stkscan[var; pos]], i. e. , returns the value of
the atom!!!: as of position pOSe
stkeval[pos;form]
is a more general evalv.
evaJl[form] at position pas,
It is equivalent to
i.e., all uartabLe&
evaJluated in form, will be evaluated as of pos. B
Finally, we have two functions which clear the stacks:
retfrom[pos;value]
clears the stack back to the function at position
pos I' and effects a return from that function with
vall!! as its value.
reteval[pos;form]
clears the stack back to the function at position
pos..
value
t.hen
to
evaluates form and returns with
the next
higher
functio~.
In
its
other
words, reteval[pos,form] is equivalent to
ret1:rom[pos ;stkeval[ pas; form]]. 9
8---~~~;~;;:-;~;-;~~~~;~~;-;~-;~;:;-;~;~-;;;~;;;~;i,i;-;;;;;;~~;-;~;-;;;~;:-::;::
stkpos, stknth, retfrom, etc., 'see' the stack as it currently is.
page 12.11-13 for descri~ti n of how stkeval is implemented.)
9
Provided form does
footnote 8-.-
not
in'folve any stack functions,
12.10
as
(8ee
explained
in
We also have:
mapdl[mapdlfn:mapdlpos]
starts at position mapdlpos (current if NIL), and
applies mapdlfn to the function !!!!!!! at each
pushdown
position,
i.e.,
to
stkname[mapdlpos]
until the top of stack is reached.
Value is NIL.
mapdlpos is updated at each iteration.
For example. mapdl[(LAHBOA (X) (ANO' (EXPRP X) (PRINT X»)] will print all exprs
on the push-down list.
mapdl[(LAHBOA (X) (CONO «GREATERP (STKNARG HAPOLPOS) 2) (PRINT X] will
print
all functions of more than two arguments.
searchpd1[srchfn:srchpos]
searches the pushdown list starting at position
srchpos (current if NIL) until it finds a position
for which srchfn applied to the n!m! of the
function called at that position is not NIL. Value
is (NAME • position) if such a position is found,
otherwise
NIL.
srchpos
is
updated
at
each
iteration.
The Pushdown List and Funaro
The
linear
interrupted
scan up ,the parameter stack for a variable bind,ing
by
can be
a special mark called a skip-blip appearing on the stack in a
name position (See Figure 12-1).
In the value position is a pointer to the
posi tion on the stack where the search is to be continued.
used to ,make stkeval. page 12.10 work.
This is what is
It is also used by the funarg device
(Section 11).
When a funarg is applied, INTERLISP puts a skip-blip on the parameter stack
12.11
wi th a pointer to the funarg array, and another skip-blip at the top of the
funarg array pointing back to tho stack.
like it has a patch.
The effect is to make the stack look
The names sind values stored in the funarg, array, will, thus
be seen before those higher on title stack.
Similarly, setting a variable whose
binding ,is contained in the fUflarg array will change only the array.
Note
however that as a consequence 01: this implementation, the &ame instance 0/
lunar, object cannoet be u&ed, rectJ'r.sil1el,l.
12.12
fI
USE OF 'SKIPBLIPS'
PARAMETER
STACK
PARAMETER
STACK
•
•
•
•
•
NM
NM
NM
NM
SKIP
NM
NM
VAL
VAL
•
.-
•
•
• VAL r+
VAL
•
VAL
VAL
NM
NM
SKIP
NM
VA
NM. VAL
f.4--
•
•
ARGUMENTS
TO STKEVAL
•
BEGIN
EVALUATION OF
FORM
•
•
•
STKEVAL
FUNARG
FIGURE 12-1
12.13
FUNARG
ARRAY
Index for Section 12
Page
Numbers
association list
back trace
................
t
••••••••••••••••••••••
control pushdown list
debugging
eval-blip
EVALV[VAR;POS]
free variables ...••...•.•....••••••••••••••••••••
free variables and compiled functions •••••••••••
FSTKARG[N;POS] BUBR
FSTKNTH[N;POS] BUBR
FUNARG
,* •••.•••• ••••••
ILLEGAL STACK ARG (error m~ssage)' ~ ••••••••••••••
locally bound variables
MAPOL[MAPOLFN;MAPOLPOS]
number stack .........•••• ~.~ •••• i • • • • • • • • • • • • • • •
parameter pushdown list ••
•••••••••••••••••••
pushdown 1 is t
~
ot
••••••••
0
• • • • • • • •' • • • • • • • • • • • • • •
............ ,.••...••.....•.......•.
pushdown list functions ..
RETEVAL[POS;FORM] BUBR
RETFROM[POS;VALUE] BUBR
searching the pushdown list
SEARCHeOL[SRCHFN;SRCHPOS]
skip .. blip
slot (on pushdown list) •• " • '. '0' • • • • • • • • • • • • • • • • • •
stack position
STKARG[ N; POS] SUBR
STKARGS[POS]
.,
STKEVAL[POS;FORM] SUBR • ,. • 'I ••••••••••••••••••••••
STKNAME[POS] SUBR
STKNARGS[POS] SUBR
STKNTH[N;POS] BUBR
STKPOS[FN;N;POS]
STKSCAN[VAR;POS] SUBR
••••••••••••••••
0
••••••••••••••••••••••
t1
••••• ' •••••••••••••••••
.............. ......... ........... .
•••' • • • •
It • • • • • • • • • • • • • • • • • • • • • •
'
value cell
...............
variable bindings
VARIABlES[POS]
f·
••••••••••••••••••••••
....•••• ~ ••••••••••••••••••••••
10
-FORM-
• • • • • • • • • • • • • • • • • • • • • • • • • • e. • • • • • • • • • • • • • • •
INDEX.12.1
12.1-2
12.2,4
12.2
12.2
12.4
12.10
12.2,5
12.5
12.8
12.7
12.11-12
12.6
12.6
12.11
12.2
12.2,8-9,11
12.1-13
12.6-11
12.10
12.10
12.6,9
·12.11
12.11
12.2,6,8,10
12.6-7,9-10
12.8-9
12.9
12'.10-11
12.7
12.8
12.7-9
12.6-7,9
12.10
12.1
12.1-6
12.9
12.4-5
12.4
SECTION 13
NUftBERS AND ARITHftETIC FUNCTIONS
13.0
General Comments
There are three different types of numbers in INTERLISP: small integers, large
integers, and floating point numbers. 1 Since a large integer or floating point
number can be (in value)' any 36 bit quantity (and vico versa), it 1s necessary
to distinguish between those 36 bit quantities that represent large integers or
floating point numbers, and other INTERLISP pointers.
We do this by -boxing-
the number, which is sort of like a special ·cons·: when a large integer or
floating pOint number is created (via an arithmetic operation or by read),
INTERLISP gets a new word from -number storage· and puts the large integer or
floating point number into that word.
INTERLISP then passes around the pointer
to that word, i.e., the -boxed number-, rather than the actual 36 bit quantity
i tse If.
Then when a numeric function needs the actual numeric quantity, 1t
performs the extra level of addressing to obtain the -value- of the number.
This latter process is called ·unboxing-.
Note that unboxing does not use any
storage, but that each boxing operation uses one new word of number storage.
Thus, if a computation creates many large integers or floating point numbers,
i.e., does lots of boxes, it may cause a garbage collection of large integer
space, GC: 18, or of floating point number space, GC: 16.
1----------~---~-~----------~--------~------~-----------------------------~----
Floating point numbers are created by the read program when a • or an E
appears in a number, e. g. 1000 is an integer, 1000. a floating point
number, as are lE3 and I.E3. Note that 10000, 1000F, and IE30 are perfectly
legal literal atoms.
13.1
13.1
I~teger
Arithmetic
Small Integers
Small integers are those integers for which smallp is true, currently integers
whose absolute value is less thalll 1536.
Small integers are boxed by offsetting
them by a constant so that they overlay an area of INTERLISP's address space
that does not correspond to any [NTERLISP data typo. 'Thus boxing small numbers
does not use any storage, and furthermore, each small number has a unique
representation, so that
not
be
used
for
~
may be used to check equality.
large
eq[2000;addl[1999]] is NIL!
in'tegers
~
or
floating
Note that
point
~
numbers,
should
e. g. ,
or equal must bo used instead.
Integer Functions
All of
the functions described below work on integers.
Unless specified
otherwise, i f given a floating I.oint number, they first convert the number to
an integer by truncating the fractional
bit~,
e.g., iplus[2.3;3.8]=5; if given
a non-numeric argument, they generate an error, NON-NUMERIC ARG.
It is important to use the integer arithmetic functions, whenever pOSSible, in
place of the more general arithmetic functions which allow mixed floating point
and integer arithmetic, e.g.,
~lus
integer functions compile o'pen,
vs plUS, igreaterp vs greaterp, because the
and therefore run faster than the general
ari thmetic functions. and because the compiler is ·smart· about eliminating
unnecessary boxing and unboxlng.
Thus, the expression
(IPLUS (IQUOTIENT (ITIHES N 100) H) (ITIMES X Y»
will compile to perform only
one box, the outer one, and the expression
(IGREATERP (IPLUS X Y) (IDIFFEREHCE A B»
13.2
will compile to do no boxing at all.
Note that the POP-1Q 1$ a 36 bit machine. so that all integers are between
-2t35 and 2t35-1. 2 Adding two integers which produce a result outside this
range causes overflow, e.g., 2t34 + 2t34.
The procedure on overflow is to return the largest possible integer, i •••
2t35 - 1. 3
Xi
+ Xz + ••• +
iminus[x]
- x
idifference[XjY]
x - Y
add1[x]
x+
sub1[x]
x .;. 1
"n
1
the product of !l'!Z' ••• !"
iquotient[x;y]
x/y truncated, e.g., iquotient[3:Z]-1,
iquotient[-3,Z]--1
iremainder[x;y]
the remainder when !
is divided by l'
e.g.,
iremainder [3:2]-1
igreaterp[x;y]
T if x > y: NIL otherwise
2-----------------------------------------------------------------------------Approximately 34 billion
3
If the overflow occurs by trying to create a negative number of too large a
magnitude, -2t35 is used inst.ad of 2t35-1.
13.3
< y; NIL otherwise
ilessp[x;y]
T is x
zerop[x]
defined as eq[x;O].
Note that zerop should not be u.sed for floating point numbers because 'it uses
~.
Use eqp(x,O] instead.
minusp[x]
T jLf !
is ne,gative;
Does not
NIL otherwise.
con'vert ! to an integer, but simply checks sign
bit.
eqp[n;m]
T jLf !! and
othf3rwise.
m are
(!!9.
!,g.
or equal numbers,
may be used if !!. and
to Ibe small integers.)
~
NIL
m are known
does not convert !!. and
m to integers, e.g., eqp[ZOOO;ZOOO.3]=NIL, but it
can be used to compare an integer and a floating
\
point number, e.g., eqp[ZOOO;ZOOO.O]=T.
not generate an error if !! or
smallp[n]
mare
!!9.2 does
not numbers.
T if !! 15 a small integer, else NIL.
smallp does
not generate an error if !! is not a number.
fixp[x]
! if ! is an integer, else NIL.
Does not generate
an ttrror i r ! is not a number.
fix[x]
Converts ! to an integer by truncating fractional
bits, e.g., flx[Z.3] = Z, fix[-1.7] = -1.
If
~
is
alrElady an integer, fix[x]=x and doesn't use any
stor'age .4
4------------------------------------------------------------------------------Since FIX is also a lispx leommand (Section ZZ), typing FIX directly to
1 ispx wi 11 not cause the func:tion fix to be called.
13.4
lambda no-spread, value is logical and of all its
arguments, as an integer, e.g., 10gand[7;5;6]-4.
lambda no-spread, value is the logical
its
arguments,
as
an
~
of all
integer,
e.g.,
logor[ 1;3 ;9]-11.
lambda no-spread, value is the logical exclusive
~
of
its
arguments,
as
an
integer,
e.g.,
10gxor[II;5] • 14,
10gxor[11;5;9] • 10gxor[14;9] • 7.
lsh[n;m]
(arithmetic) left shift, value is n*Ztm,i.e.,
shifted left !!! places.
negative.
~
is
!1 can be positive or
I f ! is negative,
~
is shifted ri,ht
-m
places.
rsh[n;m]
(arithmetic) right shift, value is n*Zt-m, i.e.,
is shifted right
negative.
llsh[n:m]
mplaces.
!1 can be positive or
If!!! is negative, !1 is
logical left !hift.
~
On PDP-10,
le/t -! places.
!!!h
is equivalent
to Ish.
lrsh[n:m]
!ogica~
right !hift.
The difference between a logical and arithmetic right shift lies in the
treatment of the sign bit for negative numbers.
For arithmetic right shifting
of negative numbers, the sign bit is propagated, i.e., the value is a negative
number.
For logical right shift, zeroes are propagated.
Note that shifting
(arithmetic) a negative number 'all the way' to the right yields -1, not O.
13.5
13.2
Floating Point Arithmetic
All of the functions described below work on floating point numbers.
Unless
specified otherwise, if given an integer, they first convert the number to a
floating point number, e.g., fIJlus[I;2.3] = fplus[I.0;2.3] • 3.3; it' given a
non-numeric argument, they generate an error, NON-NUMERIC ARG.
The largest floating point number is 1.7014118£38, the smallest positive (nonzero) floating point number is 1.4693679E-39.
same as for integer arithmetic.
For underflow, i.e. trying to create a number
o.
of too small a magnitude. the value will be
fminus[x]
The procedure on overflow is the
- x
X1
* xZ .
•••
• xn
fquotient[x;y]
x/y
fremainder[x;y]
the remainder when !
is divided by l.
e.g.,
fremainder[I.0:3.0]= 3.72529£-9.
minusp[x]
T if ! is negative; NIL otherwise.
Wdrks for both
integers and floating point numbers.
eqp[x;y]
T i1F !
and l
are g, or equal numbers.
discussion page 13.4.
fgtp[x:y]
T if x ) y, NIL otherwise.
13.6
8ee
is !
floatp[x]
if !
otherwise.
is
a
floating
point
NIL
number;
Does lIot give an error if ! is not a
number~
Note that il numberp(x} is true. thell either /txp(x} or Iloatp(x] is true.
float[x]
Converts !
to a floating
point number,
e.g.,
flo.t[O] • 0.0.
13.3
The
Mixed Arithmetic
functions
in this section are
'contagious floating point ,arithmetic'
functions, i.e., if any of the arguments are ,floating point numbers, they act
exactly like floating point functions, and float all arguments, and return a
floating point number as their value.
Otherwise, they act like the integer
functions.
argument,
If
given
a
non-numeric
they
generate
an
error,
NON-NUMERIC ARG.
minus[x]
- x
difference[x;y]
x - y
quotient[x;y]
if
!
and
I
are
both
integers,
\
value
is
iquotient[xiY], otherwise fquotient[x;y].
remainder[x;y]
if
!
and
I
are
both
integers,
value
iremainder[x;y], otherwise fremainder[xiY].
13.7
is
greaterp[x:y]
T if x > y, NIL otherwise.
lessp[ x ;.Y]
T if x < Y. NIL otherwise.
abs[x]
! if x
minl~,
13.4
> O.
otherwise -x.
!!!! uses greaterp
and
(not igreaterp and iminus).
Special Functions
These functions are all "borrowI9d" from the FORTRAN library and handcoded in
INTERLISP via ASSEMBLE by J. W. Goodwin.
They utilize a power series expansion
e.g., 5in[30]-.5
and their values are (supposed to be) 27 bits accurate,
exactly.
expt[m:n]
If!!! is an integer and !!. is a
value is mtn.
positive
integer.
value "is
an
integer,
e.G,
exp1~[3;4].81,
otherwise the value is a floating
point number.
If!!! is negative and !!. fractional,
an error is generated.
sqrt[n]
value is a square root of !! as a floating point
number.
!!
may
be
fixed
or
floating
Generates an error if !! is negative.
point.
sqrt[n] is
about twice as fast as expt[n;.5]
log[x]
valllie is natural logari thm of !
pOint number.
antilog[x]
as a floating
! can be integer or floating pOint.
value is floating point number whose logarithm 1s
!.
!
can be integer or floa.ting point,
antilog[l] - e • 2.71828 •••
13.8
8.g.,
sin[x;radiansflg]
! in degrees unless radlansflg=T. Value 1s s1ne of
! as a floating point number.
cos[x;radiansflg]
Similar to sln.
tan[x:radiansflg]
Similar to sin.
arcsin[x:radiansflg]
!
is a number between -1 and 1 (or an error is
generated).
point
The value of arcsin is a floating
is
and
number,
radiansflg=T.
In
in
degrees
other
arcsin[x;radiansflg]-! then
unless
words,
if
sin[z;radiansflg]=!.
The range of the value of arcsin is -90 to +90 for
degrees, -n/2 to n/2 for radians.
arccos[x,radiansflg]
Similar to arcsin.
Range is 0 to 180, 0 to
arctan[x;radiansflg]
Similar to arcsin.
Range is 0 to 180, 0 to n.
rand[lower:upper]
Valu~
ft.
is a pseudo-random number between lower and
upper inclusive, i.e. rand can be used to generate
a sequence of random numbers.
integers,
the
value
of
If both limits are
rand
is
an
integer,
otherwise it is a floating point number.
The
algorithm is completely deterministic, i.e. given
the same initial state, rand produces the same
sequence of values.
The internal state of rand is
ini tialized using the function randset described
below,
and
randstate.
13.9
is
stored
on
the
free
variable
Val1IJe is internal state of rand after randset has
randset[x]
finished
operating,
int'Bgers.
~=T,
If
~=NIL,
as
a
dotted
pair
of
two
value is current state.
If
rands tate is initialized using the clocks.
Othl9rwise. ! is interpreted as a previous internal
sta·teti.e. a value of randset, and 1s used to
reslBt randstate.
13.5
For example,
1.
(SETO OLDSTATE (RANOSET»
2.
Use rand to generate some random numbers.
3.
(RAHDSET OLDSTATE)
4.
rand will generate same sequence as in Z.
Reusing Boxed Numbers - SETH
rplaca and rplacd provide a way of cannibalizing list structure for reuse in
order to avoid making new structure and causing garbage collections. 6 This
section describes an analogous function for large integers and
numbers, setn.
floa~ing
point
setn is used like setq, i.e., its first argument is considered
as quoted, its second is evaluated.
set is a large integer or
If the current value of the variable being
point number, the new value is deposited
into that word in number storage., i.e., no new storage is used. 8 If the current
floa1~ing
value is not a large integer or' floating point number, e.g., it can be NIL,
setn operates exactly like setg, i.e., the large integer or floating point
number is boxed, and the variable is set.
This eliminates initialization of
the variable.
6-------------------------------··---~---------------- --------------------------
This technique is frowned upon except in well-defined, localized situations
where efficiency is paramount.
6
The second argument to setn must always be a number or a NON-NUMERIC ARG
error is generated.
13.10
setn will work interpretively, i.e., reuse a word in number storage, but will
not yield any savings of storage because the boxing of the second argument will
still take place, when it is evaluated.
The elimination of a box is achieved
only when the call to setn is compiled, since !!!n compiles open, and does not
perform the box if the old value of the variable can be reused.
Caveats concerning use of SETH
There are three situations to watch· out for when using!!!n-
The first occurs
when the same variable is being used for floating point numbers and large
integers.
If the current value of the variable is a floating point number, and
it is reset to a large integer, via !!!rr. the large integer is Simply deposited
into a word in floating point number storage, and hence will be interpreted as
a floating point number.
Thus.
"(SETQ FOO 2.3)
2.3
,,(SETH FOO 10000)
2. 189529E-43
Similarly. if the current value is a large integer, and the new value is a
floating point number. equally strange results occur.
The second situation occurs when a !!!! variable is reset from a large integer
to a small integer.
large
integer
In this case, the small integer is simply deposited into
storage.
It
will
then
print
correctly,
and
function
arithmetically correctly, but it is not a small integer. and hence will not be
~
to another integer of the sam. value, I.g.,
13.11
.. (5ETQ FOO 10000)
10000
.. ( SETN F4)() 1)
1
.. (IPlUS FOO 5)
6
"(EQ Foo 1)
NIL
"(5MALLP FOO)
NIL
In particular, note that zerop WJl1l return NIL even if the variable is equal to
O.
Thus a program which begins with FOO set to a large integer and counts it
down by (SETH FOO (SUBI FOO»
mu~.t
terminate with (fQP FOO 0), not (ZEROP FOO).
Finally, the third situation to IIlatch out for occurs when you want to save the
current value of a setn variable for later use.
For example, if FOO is being
used
its
by
setn,
and
the
user wants
to
save
current
value
on
FIE,
(SETQ FOO FIE) is not surficent, since the next setn on Foo will also change
FIE, because its changes the wQlrd in number storage pointed to by FOO, and
hence
pointed
to
by
FIE.
The
number
must
be
copied,
e.g. ,
(SETQ FIE (IPlUS FOO», which sets FIE to a new word in number storage.
setn[var;x]
nlarrtbda function like setq.
y.!.!:
is quoted, ! is
evaluated, and its value must be a number.
will be set to this number.
of Y!r is a large
number,
that
cannibalized.
word
If the current value
integer or floating
in
y!.!:
number
storage
point
is
The value of setn is the (new)
value of !!!..
13.6
Box and Unbox
Some applications may require that a user program explicitly perform the boxing
and unboxing operations that ar"e usually implicit (and invisible) to most
13.12
programs.
The
respectively.
functions
that
perfona these operations are
loc
and vag
For exam'ple, if • user program executes a TENEX J8YB using the
ASSEMBLE directive. the value of the ASSEMBLE expression will have to be boxed
--») ..
to be used arithmetically, e.g., (IPlUS X (lOC (ASSEMBLE
It must be
emphasized that
Arbi trarll unboxed numbers should not be passed around flS
because they can cau.se trouble lor the garbage collector.
ordtnflrll
l1.lue.t
For example, suppose the value of 2S were 150000, and you created (VAG X), and
this just happened to be an address on the free storage list] The next garbage
collection could be disastrous.
For this reason t the function vag must be
~sed
with extreme caution when its argument's range is not known.
One place where vag is safe to use is for performing computations on stack
positions, which are simply addre.s.ses of the corresponding positions (cells) on
the stack.
them.
To treat these addresses as -"umbers, the program must first box
Conversely, to convert numbers to corresponding stack positions, the
program must unbox them.
Thus, suppose ! were the value of stkarg, i.e. II
corresponds to a position on the parameter stack.
To obtain the next position
on the stack, the program must compute (VAG (ADD1 (lOC X»). Thus if
132002,7
(lOC X)
would
be
~
3Z00ZQ,8 (ADD1 (LOC X»
would
be
~
were
32003Q,
and (VAG (ADD1 (lOC X») would be 13Z003.
Note that rather than starting with a number, and unboxing it to obtain its
numeric quantity, here we started with an address, i.e., a 36 bit quantity, and
7---~----------------------------··---·-------------------------.-----------~-An INTERLISP pointer (address) which does not correspond to the address of
a list structure, or an atom, or a number, or a string, is printed· as In, g
given in octal.
B
Q following a number means the numeric quantity is expressed in octal.
13.13
wishing to treat it as a number" boxed it.
For example, loc of an atom, e.g.,
(LOC (QUOTE FOO», treats the atom as a 36 bit quantity. and makes a number out
of it.
If the address of the a1tom FOO were 125000, (LaC (QUOTE fOO»
125000, i.e. the location of
f~).
would be
It is for this reason that the box operation
is called loc, which is short for location. 9
Note that FOO does not print as 1364110 (125000 in octal) because the print
routine recognizes that it is nn atom, and therefore prints it in a special
way,
i.e.
by
printing the individual characters that comprise
it.
Thus
(VAG 125000) would print as fOO, and Ulould be in fact fOO.
loc[x]
Plaktas
a number
out
of !,
i. e. ,
returns
the
location of !.
vag[x]
The inverse of loco
of
The
compiler
eliminates
(IPLUS X (LOC (ASSEMBLE
--»)
~~
! must be a number; the value
is the unbox of !.
Iltxtra
vag's
and
loc's
for
example
will not box the value of the ASSEMBLE, and then
unbox it for the addition.
9------~-~--------~------------------------~-------------------------------~~-~
vag is an abbreviation of Y,!lue set.
13.14
Index for Section 13
Page
Numbers
ABS[X]
AOOl[X]
ANTILOG[X]
ARCCOS[X;RADIANSFLG]
ARCCOS: ARG NOT IN RANGE (error message)
ARCSIN[X;RADIANSFLG]
ARCSIN: ARG NOT IN RANGE (error message)
ARCTAN[X.RADIANSFLG]
arithmetic functions
ASSEMBLE
box
boxed numbers
boxing
COS[X;RAOIANSFLG]
OIFFERENCE[X;Y]
EQP[X;Y] SUBR
EQUAL[X;Y]
EXPT[M;N]
FGTP[X;Y] SUBR
FIX[X]
FIXP[X]
FlOAT[X]
floating point arithmetic
floating point numbers
FlOATP[X] SUBR
........
.........................................
...........................................
.. .............................. ..
·
.................................
.................................... .
..................................
............... ......................... .
'
~
FHINUS[X]
••••
s
• • • • • • • • • • •, • • • • • • • • • • • • • • • • • • •
FPlUS[Xl;X2; ... ;Xn] SUBR*
FQUOTIENT[X;Y] SUBR
FREHAINOER[X;Y] SUBR
FTIHES[Xl;X2; ... ;Xn] SUBR*
GC: 16 (typed by system)
GC: 18 (typed by system)
GREATERP[X;Y] SUBR
IOIFFERENCE[X;Y]
IGREATERP[X;Y] SUBR
IlESSP[X;Y]
ILLEGAL EXPONENTIATION: (error message)
........................
.........................
IMINUS[X]
•••••••••••••••••••••••••••••••••••• ,,'.
..............................
integer arithmetic
IPlUS[Xl;X2; ... ;Xn] SUBR*
IQUOTIENT[X;Y] SUBR
IREMAINOER[X;Y] SUBR
ITIHES[Xl;X2; ..• ;Xn] SUBR*
large integers
lESSP[X;Y]
LLSH[N;H] SUBR
lOC[X] SUBR
LOG[X]
lOGANO[Xl;X2; .•. ;Xn] SUBR*
LOGOR[Xl,X2; .•• ;Xn] SUBR*
lOGXOR[Xl;X2; ..• ;Xn] SUBR*
LRSH[N;H]
LSH[N,H] SUBR
"
HINUS[X] SUBR
HINUSP[X] SUBR
mixed arithmetic
.......................
..................................
............................. ........ .
'
.......................
........ ........................ ..
··.................................
................................
INDEX .'13.1
13.8
13.3
13.8
13.9
13.9
13.9
13.9
13.9
13.Z-10
13.13
13.14
13.1
13.1-Z,10-12
13.9
13.7
13.Z,4,6
13.2
13.8
13.6
13.4
13.4
13.7
13.6-7
13.1-2,4,10
13.7
13.6
13.6
13.6
13.6
13.6
13.1
13.1
13.8
13.3
13.3
13.4
13.8
13.3
13.Z-5
13.3
13.3
13.3
13.3
13.1-2,10
13.8
13.5
13.13-14
13.8
13.5
13.5
13.5
13.5
13.5
13.7
13.4,6
13.7-8
Page
Numbers
NON-NUMERIC ARG (error message)
numbers
octal
overflow
PlUS[Xl;X2; ... ;Xn] SUBR*
Q (following a numb~r)
QUOTIENT[X;Y] SUBR
RAND[lOWER;UPPER]
random numbers
RANDSET[X]
RANDS TATE
REMAINDER[X;Yl SUBR
RSU[N;M]
SETN[VAR;X] NL
SIN[X;RADIANSFlG]
small integers
SMAllP[N]
SQRT[N]
SQRT OF NEGATIVE VALUE (error message)
SUBl[X]
TAN[X;RADIANSFlG]
TENEX
TIMES[Xl;XZ; ... ;Xn] SUBR*
unboxed numbers
unboxing
VAG[X] SUBR
ZEROP[X]
I (followed by a number)
•
< •••••••
................................
......................................
INOEX.13.Z
13.2,6-7
13.1-14
13.13
13.3,6
13.7
13.13
13.7
13.9
13.9
13.10
13.9-10
13.7
13.5
13.10-12
13.9
13.1-2
13.2,4
13.8
13.8
13.3
13.9
13.13
13.7
13.13
13.1-2,12
13.13-14
13.4
13.13
SECTION 14
INPUT/OUTPUT FUNCTIONS
Files
14.'1
All input/output functions in INTERLISP can specify their' source/destination
file with an optional extra argument which is the name of the file.
must be opened as specified below.
This file
If the extra argument is not given (has
value NIL) •. the file specified as ·primary· for input (output)
Normally these are both T. for teletype input and output.
is used.
However, the primary
input/output file may be changed by
input[file]l
Sets fIle as the primary input file.
Its value is
the name of the old primary input file.
input[] returns current primary input file, which
is not changed.
output[file]
Same as input except operates on primary output
file.
Anll file which i& made primarll mu&t haue been preuiou&l,l
input/output, except lor the file T, .hich i& al.all& open.
opened
lor
1---~-------------------------------------------------------------~-----------The argument name file is used for tutorial purposes only. The arguments
to
all subrs are U.~and Was described in arg1ist, Section 8.
14.1
Opens file for input, and sets it as the primary
infile[ r'ile]
input file. 2 The value of infile is the previous
prililary input ·file.
as input[file].
If file is already open, same
Generates a FILE WON'T OPEN error
if file won't open, e.g., file is already open for
outl,ut.
Opens file for output, and sets it as the primary
outfile[file]
output f11~.3 The value of outfile is the previous
priulary output file.
If file is already open,
samEI as output[file].
Generates a FILE WON'T OPEN
errcJr if file won't open, e.g., if file is already
open for input.
For all input/output functions,
names,
i.e.
file
can be
file follows the TENEX conventions for file
prefixed by a directory name enclosed
in
angle
brackets, can contain alt-modes or control-F's, and can include suffixes and/or
version numbers.
Consistent with TENEX, when a file is opened for input and no
version number is given, the highest version number is used.
Similarly. when a
file is opened for output and no version number is given, a new file is created
with a version number one highelr than the highest one currently in use with
that file name.
Regardless of the file name given to the INTERLISP function that opened the
2-----~-----------------------------------------------------------~-----------To open fi Ie without changing the primary input file,
perform
input[infile[file]].
8
To open file without
output[outfile[f1le]].
ch,snging
the
14.2
primary
output
file,
perform
file, INTERLISP maintains only full -TENEX file names4 in its internal table of
open files and any function whose value is a file name always returns a full
file name, e.g. openp[FOO]=FOO.;3. Whenever a file argument is given to an ilo
function, INTERLISP first checks to see if the file is in its internal table.
If not, INTERLISP executes the appropriate TENEX JSYS to -recognize- the file.
If TENEX does not successfully recognize the file, a FILE NOT FOUND error is
generated. 6 If TENEX does recognize the file, it returns to INTERLISP the full
file name.
Then, INTERLISP can continue with the indicated operation.
If the
file is being opened, INTERLISP opens the file and stores its (full) name in
the file table.
If it is being closed, or written to or read from, INTERLISP
checks its internal table to make sure the file is open, and then executes the
corresponding operation.
Note that each time a tull file name is not used, INTERLISP must call TENEX to
recognize the name.
Thus if repeated operations are to be performed, it is
considerably more efficient to obtain the full file name once, e.g. via infilep
or outfllep.
Also. note that recognition by TENEX is performed on the user's
entire directory.
Thus, even if only one file is open,
say FOO.;I,
FS
(F altmode) will not be recognized if the user's directory also contains the
file FIE.: 1. Similarly, it is possible for a file name that was previously
recognized to become ambiguous.
for example, a program performs infile[FOO],
opening FOO.: 1, and reads several expressions from FOO. Then the user types
control-C, creates a FOO.:2 and reenters his program.
Now a call to read
giving it Foo as its file argument will generate a FILE NOT OPEN error, because
TENEX will recognize FOO. as FOO.:Z.
6
except for infilep, outfilep and openp, which in this case return NIL.
14.3
infilep[file]
Ret;urns full file name of file if recognized by
TE~JEX.
NIL otherwise.
The full file name will
cOl1ltain a directory field only if the directory
differs from the currently attached directory.
Recognition
is
in
ver'sion number
input context,
is given,
the
i.e.
highest
if
no
version
nuaber is returned.
in/tlep and outlilep do not open anu lile&. or change the primaru Itle&, theu
are pure predicate&.
outfilep[file]
Similar to
infilep,
output context,
given,
i.e.
a version
except
is
in
if no version number
is
number
recognition
one
higher
than
the
highest version number is returned.
closef[flle]
Closes file.
Generates an error, FILE NOT OPEN,
if file not open.
close
the
teletype.
pr~mary
If file is NIL, it attempts to
primary
input
file
if
other
than
Failing that, it attempts to close the
output
file
if
other
than
teletype.
Failing both, it returns NIL. If it closes any
file, it returns the name of that file.
If it
closes either of the primary files, it resets
tha~
prilDary file to teletype.
closeall[ ]
Closes all open files (except T).
Value is a list
of the.files closed.
openp[file;type]
If
~~=NIL,
value is file (full name) if
open either for reading or for writing.
value is NIL.
14.4
~
is
Otherwise
If !lI!.! is INPUT or OUTPUT, value is file if open
for corresponding type, otherwise NIL. If !l2! is
BOTH, value is file if open for both input and
output, (See iot11e, page 14.6) otherwise NIL.
Note: the value of .2J!!!!.I! is NIL if file 1s not
recognized, 1.8 • .2J!!!!.I! does not generate an error.
openp[] returns a list of all files open for input
or output, excluding T.
Addressable files
For
most
applications,
files
are
read
starting at
their
beginning
and
proceeding sequentially, i.e. the next character read is the one immediately
following the last character read.
Similarly; files are written sequentially.
A program need not be aware of the fact that there is a file pointer associated
,
with each file that points to the location where the next character is to be
read from or written to, and that this file
after each input or output operation.
Th~s
~ointer
is automatically advanced
section describes a function which
can be used to reposttton the file pointer, thereby allowing a program to treat
a file as a large block of auxiliary storage which can be access randomly.B For
example, one application might involve writing an expression at the be,tnntn,
of the file, and then reading an expression from a specified point in its
6-·-----~--------------------------------------------------------~-------------Random access means that any location is as quickly accessible as any
other. For example, an array is randomly accessible, but a list is not,
since in order to get to the n!h element you have to sequence through the
first n-1 elements.
14.6
mtddle.?
A file used in this fashion is. much like an array in that it has a certain
number of addressable locations that characters can be put into or taken from.
However,
unlike arrays,
files can be enlarged.
For example,
if the file
pointer is positioned at the end of a file and anything is written, the file
"grows." It is also possible tIC) position the file pointer beuond the end of
file and then to write. 8 In this case, the file is enlarged, and a "hole" is
created, which can later be wr'itten into.
Note that this enlargement only
takes place at the end of a file: it is not possible to make more room in the
middle of a file.
In other words, if expression A begins at positon 1000, and
expression B at 1100, and the program attempts to overwrite A with expression
C, which is 200 characters long, part of B will be clobbered.
1ofile[file]
Opens file for both input and output.
fil!.
Does not change either primary input or
primary output.
default
Value is
is
same
If no version number is given,
as
for
infile,
i.e.
highest
version number.
sfptr[file;address]
~ets file ~oin!e! for file to address. 9 Value is
7---~h~;--;;;;;;~;;;-~~~~i~--;;;~1;;;--;h~-f1i~--b;-~~~~--~~;--;;;h-~~~~~--;~d
output. This can be achie'ved via the function iorile described below.
However, random file input lor output can be performed on files that have
been opened in the usual way by infile or outfile.
8
If the program attempts to read beyond the end of file, an END OF FILE
error occurs.
9
TENEX uses byte addressing; the address of a character (byte) is the number
of characters (bytes) that precede it in the file, i.e., 0 is the address
of the beginning of the file. However, the user should be careful about
computing the space needed for an expression, since end-of-line is
represented as two characters in a file, but nchars only counts it as one.
14.6
old setting.
file. 10
address--1 corresponds to the end of
If address-NIL, sfptr returns the current value of
file pointer without changing it.
fi1epos[x;file:start;end;skip;tail]11
10).
Searches f!!! for! a lastrpos (Sec'tion
Search begins at start (or if start=NIL,
the current position of file pointer), and goes to
end (or if !.rul=NIl, to the and of file).
address
Value is
of start of match, or NIL if not found.
skip can be used to specify a character which
matches any character in the file.
If tail is T,
and the search is successful, the value is the
address of the first character alter the sequence
of characters corresponding to !, instead of the
starting address of the sequence.
In either case,
the file is left so that the next i/o operation
begins _at the address returned as the value of
filepos.
1j------~----------------~~---------------------------------------------------Note:
if a file is opened for output only, either by outfile, or
openf[ file; 100000q] (see page 14.8), TENEX assumes that one intends to
write a new or different file, even if a version number was specified and
the corresponding file already exists. Thus, sfptr[file;-1] will set the
fi Ie pointer to O. If a file is opened for both reading and writing,
either by iofile or openf[file:300000q]. TENEX assumes that there might be
material on the file that the user intends to read. Thus, the initial file
pointer is the beginning of the file, but srptr[file;-l] will set it to the
end of the file. Note that one can also open a file for appending by
openf[file;20000q]. In this case, the file pointer right after opening is
set to the end of the existing file. Thus, a write will automatically add
material at the end of the file, and an sfptr 1s unnecessary.
'
t1
filepos was written by J.W. Goodwin.
14.7
Openf
opens file.
openf[file;x]
aCCIBSS
! is a number whose bits specify the
and mode for file, i . e. ! corresponds to
the second argument to the TENEX JSYS OPENF (see
JSY.s Manual).
Value is full name of file.
openf permits opening a file fc.r read, write, execute, or append, etc.
and
allows specification of byte size, i.e. a byte size of 36 enables reading and
writing of full words.
openf does not affect the primary input or output file
set tings, and does not check wh4!ther the file is already open - i. e. the same
file can be opened more than once, possibly for different purposes. 12 openp
will work for files opened with !!)penf.
The first argument to openf can also be a number, which is then interpreted as
JfN.
This results in a more eff'1cient call to openf. and can be signficant if
the user is making frequent call:s to openf, e.g. switching byte sizes.
JfN functions" 3
JFN stands for Job file !lumber.
It is an integral part of the TENEX file
system and is described in [Plur't], and in somewhat more detail in the TENEX
JSYS manual.
The following function can be used to obtain the JfN for an
already opened file.
opnJfn[ file]
returns the JFN for
fi Ie.
If file
not
open,
generates a FILE NOT OPEN error.
i2---------------------~--------··-----------------------------~-----~---------The -thawed- bit in'! permits opening a file that is already open.
13
The JFN functions were writt4!n by J.W. Goodwin.
14.8
Example:, to write a byte on a file
[DEFINEQ (BOUT
(LAMBDA (FILE BYTE)
(LOC (ASSEMBLE NIL
(CQ (VAG BYTE»
(PUSH NP • 1)
(CQ (VAG (OPNJFN FILE»)
(POP NP • 2)
(JSYS 51Q)
(HOVE 1 • 2)]
or to read a byte from a f1le
[DEFINEQ (BIN
(LAMBDA (FILE)
(LOC (ASSEMBLE NIL
(CQ (VAG (OPNJFN FILE»)
(JSVS 50Q) ,
(HOVE 1 • 2]
Making BIN and BOUT substitution laacros can save boxing and unboxing in
compiled code.
The following functions are available for direct manipulation of JFN's:
gtjfn[file;ext;v;flags]
sets up a 'long' call to GTJFN (see JSYS manual).
file is a file name possibly containing control-F
and/or alt-mode.
ext is the default extension, y
the default version (overriden if f1le specifies
extension/version, e.g. FOO.COM;2).
flags 1s as
described on page 17, section 2 of JSYS manual.
f!!! and ext may be strings or atoms; y and flags
must be numbers. ' Value is JFN, or NIL on errors.
rljfn[ jfn]
releases jfn.
rljfn[-l] releases all JFN's which
do not specify open files.
jfns[jfnjac3]
Value of rljfn is T.
converts jfn (a slDall number) to a fl1e name.
14.9
ac3
is either NIL, ,meanlngformat the file name as
would openp or other INTERLISP file funct1.ons, or
else is a number, meaning formata<;cordingto,JSYS
manual.
The value of jfnsis atomic
e~c,ept
where
enough options are specified by ac3 to exceed atom
size
(2
100·~hara~ters).
In this case, the value
is returned as a string.
14.2
Input Functions
Most of the /unctions described below have an (optional) (!rgument l.1!!!.. which
s peciJi es the name 0/ the Ji leon which the operat ton' is
talc.6; pl ace. If
that argument is NILi theprtmarll input/ile will beus'ed.
to
Note, in all INTERLISP sumbolic files, end-of-line is indicated by the
characters carriage-return and line-feed in that order. Accordinglu, on input
from Jiles, INT¥JfI$Pwill s~,tp all ltne-feedswhich immediate"lll /ollow'
carriage-returns'.
On input /rom teletllpe, INTERLISP will echo a line-feed
whenever a carriage-return ts input.
For all input functions except ~adc and peelc, when reading /rom the teletype,
control-A erases the last character tllped in, echoing a \ and the erased
character. Control-A will not baclc.up bellong the last carriage return. ,. Typing
control-Q causes INTERLISP
print II and clear the input buller. i.e. erase
the entire line bacl to the last carriage-return. When reading from a Itle.
and an end oj file is encounte'red. all input functions close the lile and
generate an,error, END OF FILE.
to
read[file;flg]
Re~ds
one S-expression
from
file.
Atoms
are
deltmited by parentheses, brackets, double quotes,
spaces, and
carriage~returns.
To input an atom
whic:h contains one of these syntactic delimiters,
prec:eded the delimiter by the escape character X,
e.g. AB,(C, is the atom AB(C, XX is the atom X.
i~-------------------------------------------------------------~--------------~
Actually. INTERLISP skips the next character after a carriage-return
without looking at it at all.
:
'J
">r
14.10
Strings are delimited by double quotes.
To input
a string containing a double qUote or a I, precede
it by X. e.g. "ABX"C" is the string AB"C. Note
that I can always be typed even if next character
is not 'special', e.g, "AlBIC is read as ABC.
If an atom is interpretable as a number, read will
create a number, e.g. lE3 reads as a floating
point number. 103 as a literal atom, 1.0 as a
number. 1,0 as a literal atom, etc. 'Note that an
integer can be input in octal by terminating it
with a 0, e.g. 170 and 15 read in as the same
integer.
The
setting
of
radix.
page
14.22,
deteMmines how integers are printed. i.e. with or
without 0'5.
When reading f[tfm the teletllpe, all input is line-buffered to enable the action
of control-Q.
Thus no characters are actuallll .seen bll the program until a
carriage-return i.s typed. However. for reading bll read or uread. when a
matching right parenthe.si.s i.s encountered. 'he effect i.s the .same-GS though a
carriage return were tllped. i.e. the characters are tran.smitted. To indicate
thts, INTERLlSP alsoprtnt.s a carriage-return Line-feed on the teletllpe.
flg=T
suppresses
the
typed
by
following
read
parenthesis.
carriage-return
a
normally
matching
right
(However. the characters are still
given, to read - 1.e. the user does not have to
type the carriage return himself.)
ratom[f1Ie]
Reads 1n one atom from file.
Separation of atoms
16-~-----~-------------------------------------------- -------------------------
Unless control[T] has been performed (page 14.24).
14.11
is
defined
by
described below.
action
of
setsepr
and
setbrk
X is also an escape character
for ratom, and the remarks concerning control-A,
control-Q, and line-buffering also apply.
If
the
characters
comprising
the
atom
WOUld'
nonnally be interpreted as a number by read, that
number is also returned by
~.
Note however
tha't ratom takes no speCial action for • whether
or not it is a break character, 1.e. ratom never
makllts a string.
The purpose oj ratom. rstring. setbrk. and setsepr is to allow the user to
wri te his own read program wi t~lout hailing to resort to reading character bll
character and then calling pac!!:. to male atoms. The function uread (page
14.16) is auailable if the user wants to handle input as read does, i.e. same
action on parentheses, double quotes. square brackets :---etot. spaces, and
carriage-return. but in addition, to spLit atoms that contain certain
characters, as specified bU setbJ~l and setsepr.
rstring[file]
Reads in one string from file, terminated by next
break or separator character.
Control-A, control·
Q. nnd I have the same effect as with ratom.
Note that the brealt. or separatol' character that terminates a call to ratom or
rstrtng is not read bll that call" but remains in the buffer to become the first
character seen bll the next readilt, function that is called.
ratoms[a;file]
Calls ratom repeatedly until the atom ! is read.
Returns a list of atoms read. not including !.
setsepr[lst;flg]
Set separator characters.
setbrk[lst;flg]
Set brea! characters.
14.12
Value is NIL.
Value is NIL.
For both setsepr and setbrk", 1st is a list of character codes, fIg determines
the action of setsepr/setbrk as follows:
NIL
clear out old tables and reset.
o
clear out only those character"s in 1st i.e. this provides an unsetsepr and unsetbrk.
1
add characters
i.~
1st to corresponding 'table.
Characters specified by setbrk will delimit atoms, and be returned as separate
atoms themselves by ratom. 18 Characters specified by setsepr will be ignored
and serve only to separate atoms.
For example, if $ was a break character and
] a separator character, the input stream ABC]]DEFSGH]SS would be read by 6
calls to ratom returning respectively ABC, DEF, $, GH, S, S.
Note that the action of X is not affected by setsepr or setbrk.
To defeat the
action of X use escaper]. as described below.
The elements of 1st may also be characters e.g. setbrk[ (X( X» 1 has the same
effect as setbrk[(40 41)].
Note however that the 'characters' 1,2 ••• 9,0 will
be interpreted as character code$ because they are numbers.
Initially, the break characters are"[ ] ( ) and • and the separator characters
are space, tab, carriage-return, line-feed, end-of-line, and form-feed.
(Note
that • is not a break or separator character.) setbrk[ T] sets the break
characters to their initial
~ett1ngs,
and setsepr[T] does the same for the
separator characters.
getsepr[]
Value 1s a list of separator character codes.
i6--~-~--~----------~----------·---------------------- -------------------------
but have no effect whatsoever on the action of read.
14.13
getbrk[]
Value is a list of break character codes.
escape[flg]
If
flg=NIl,
chalracter.
makes
X act
like
every
other
Normal setting is escaper T].
The value of escape is the previous setting.
ratest[x]
If ! . T, ratest returns T if a separator was
enc4)untered immediately prior to the last atom
read by ratom, NIL otherwise.
If ! • NIL, ratest returns T if last atom read by
or
rat~
read
was
a
break
character,
NIL
othurwise.
If ! . 1, ratest returns T if last atom read
(by read or ratom) contained a X (as an escape
cha."acter, e. g., X[ or XAXBXC), NIL otherwise.
readc[file]
Reads the next character, including ",
Value
is
the
character.
Action
of
", etc.
readc
is
subJect to line-buffering, i. e. readc will not
return a value until the line has been terminated
even
if
a
character
has
been
typed.
control-A and contro1-Q will have
Thus,
their usual
effElct.
If control[ T] has been executed (page
14 • ~~4) ,
defeating
1ine-buffering,
readc
wi 11
return a value as soon as a character is typed.
In addition, if control-A or control-Q are typed,
reac~
will return them as values.
14.14
peekc[filejflg]
Value is the next character, but does not actually
read it,
i.e. remove it from the buffer.
If '
!!a-NIL, peekc is not subject to line-buffering,
i.e. it returns a value as soon as a character has
been typed.
If!!H-T, peeke waits until the line
has been terminated before returning its value.
This means that control-A and control-Q will be
able.to perform their usual editing functions.
lastc[file]
Value is l!!!
uread[filejflg]
(for !!ser read)..
~haracter
read from file.
Same as read except it uses
separator and break characters set by setsepr and
setbrk.
This function is useful for reading in
list structure in the normal way, while splitting
atoms containing special characters.
Thus with
space a separator character, and break characters
of ( ) • and • the input stream (IT'S EASY.) is
read by
~
as the list (IT • S EASY X.)
Note that ( ) [ ] and • must be included in the
break characters if uread is to take
action on them,
i.e.
assemble
special
lists and make
strings.
flg=T suppresses carriage-return normally typed
following a matching right parentheses.
14.11.
14.15
See page
Notel read. ratom. ratoms. peelt.(~. reade, and uread all wait lor input if there
is none. The onlll wall to te&t whether or not there i& input ioS to use
readp.
readp[file]
Value is T if there is anything in the input
buffer of file, NIL otherwise (not particularly
meaningful for. file other than T).
Note that
because of line-buffering, readp may return T,
indicating there is input in the buffer, but
read
may still have to wait.
readline[]17
rea~s
list.
a line from the teletype, returning it as a
If readp[T]. is NIL,
Othlsrwise
it
reads
readline·retU~n~
expressions,
using
NIL~
read, 1.8
until it encounters either:
(1)
a carriage-return (typed by the user) that is
not preceded by any spaces, e.g.
ABC,)
and readline returns
(2)
(A
B C)
a list terminating in a 1]1, in which case
the
list
is
included
in
the
value
·of
re4dline, e.g. A B (C D] and readline returns
(A B (C D».
17----------------------------------------------------------------------------Readline actually has two ar"guments for use by the system, but the user
should consider it as a function of no arguments.
1.8
Actually, readline performs (APPLY. LISPXREADFN T), as described in Section
22. lispxreadfn is initially READ.
14.16
(3)
an
unmatched
right
parentheses
or
right
square bracket, which is not included 'in the
value'of readline, e.g.
ABC]
and readline returns (A B C).
In the case that one or more spaces precede a carriage-return, or a list is
terminated with a ')', readline will type
• and continue reading on the
t
next line. 19 e.g.
ABC .~
••• (O-E F)
••• (X Y Z]
and readline returns (A B C (D E F) (X Y Z».
skread[ file :rereadstringtO
is a ,!!ip
.!:!!!!
function.
It moves
the
file
pointer for !!!! ahead as if one call to read had
been performed, without paying the storage and
compute cost to really read in the structure.
rereadstring is for the case where the user has
already performed some
~'s
and ratom's before
deciding to skip this expression.
In this case,
rereadstring should be the material already read
(as a
5 tr1ng) ,
and skread operates as though it
19-~--~------------------------------------------·---- -------------------------
If the user then types another carriage return, the line will terminate
e.g.
...
~
and readline returns (A B C)
20
skread was written by J.W. Goodwin.
14.17
had seen ,that material first,
paren-count,
ThEI
double-quote
thus getting its
count,
value of" skread is X)
etc.
set
up
if the #irst thing
enc:ountered was a closing paren: Xl if the read
ter'mina,ted on an unbalanced 'Xl,'
also
would ,have ,closed. ,any
i;.e'~
extant
'one) 'which
open, left
par'ens; otherwise the, value of skread is NIL.
14.3
Output Functions
Most of the lunctton$ de$crtbed below haue an (opttonal) argument,lile' 'which
specifies the name oj the Ii le on which the operation is to tale place. 11
that argument is NIL, the primaru output lile will be used.
Note: in all INTERLIS," svmbojti,c, Jile$, end-ol-line t~ indicated bli the
characters carriage-return andline-/eed in that order. Unle$s otherwise
stated carriage-return oppeartng ill the description oJ an output Junction
means carriage-return and line-feed.
t
prin1[x;file]
prilnts ! on file.
prin2[x;file]
prilllts ! on file with X' sand •• s inserted where
reqillired for it to read back in properly by read.
Both print and prin2 print lists as well as atoms and strings; prin1 is usually
used
only
for
(PRINt (QUOTE X[»
explicitly
formatting
printing
characters,
e.g.
might, ,be used to print a left square bra'cket (the X would
~
not be printed by print).
prin~~
,
.
is used for printing S-expressions which can
!,~.
then be read back into INTERLISI) with read i.e.
regular INTERLISP formatting
characters in atoms will be preceded by X's, e.g. the atom '(}Iis printed as
X(X) by prinZ.
If radix=8,
prin~
prints a
(but both print the integer in octal).
14.18
g
after integers but print does not
Prints! with X's and ·'5 inserted where required
prin3[x;file]
for it to read back in properly by uread, i.e.
uses slparator and break characters specified by
setbrk and setsepr to determine when to insert
X's.
print[x:file]
Prints the S-expression ! using prinZ: followed by
a
carriage~return
For all printing Junctions. pointers
numbers, are printed as IN, where N is
oj the pointer (regardless oJ rad(x).
correctlu. i.e .• it will read in as the
line-feed.
Its value is
~.
other than lists. strings, atoms, or
the octal representation 0/ the address
Note that this UI1,ll not read back in
atom 'IN'.
nspaces;
its value is NIL.
spaces[njfile]
Prints
terpri[file]
Prints a carriage-return; its value is NIL.
Printlevel
The print functions print, print, prin2, and prin3 are all affected by a level
parameter set by
printlevel[n]
Sets print level to !l, value is .old setting.
Initial value is tOOO.
printlevel[] gives current
setting.
The variable !l controls the number of unpaired left parentheses which will be
printed •. Below that· level. all lists will be printed as 6.
Suppose! = (A (B C (0 (E F) G) H) K).
(A (B C & H) K). and if !l
e
Then if !l
:I
2, print[x] would print
3. (A (B C (D 6 G) H) K), and if !l • 0, just &.
14.19
If printlevel is negattue. the action is similar except that a carriage-return
is inserted between all occurrences of right parenthesis immediately followed
by a left
p~rent~esis.
The printlevel setting can be changed dynamica,lly, even while INTERLISP is
printing, by typing control-P f'ollowed by a number, i.e. a string of digits,
followed by a period or exclamat:iop pOint. 21 Theprintlevel will immediately be
set to this number. 22 If. the print r ou t1:ne, is currently deeper than the new
level,
Thus,
all unfinished lists above that level will be terminated by ---)-.
if a circular or long list of atoms,
control-PO.
is, being printed out,' typing
will cause, the list,' to: be terminated.
If a period is used to terminate the printlevel setting, the printlevel will be
returned to its previous settinu after this printout.
If an exclamation point
is used, the change 15 permanent and the printlevel is not restored (until it
is changed
again)~
. Note, prtntleuel onlll alleets t~tletllpe output.
as though leuel is tn/intte.
Output to all other liles, ercts
2i-----~------------~--------------------------------- -------------------------
As soon as control-P is typed, INTERLISP clears and saves the input buffer,
clears the output burfer, rings the bell indicating it has seen the
control-P, and then waits f(]lr input which is terminated by any non-number.
The input buffer is then restored and the program c,ontinues. If the input
was terminated by other than a period or an exclamation point. 1 t 15
ignored and printing will continue, except ,that cha~acters cleared from the
output buffer will have been lost.
.
22
Another way of -turning Oflf- output is to type control-O, which simply
clears the output buffer, thereby effectively skipping the next (up to) 64 ,
character~.
14.20
14.4
Input/Output Contrel Functions
clearbuf[file;flg]
Clears the input buffer for file.
If file is T
and fig is T, contents of INTERLISP's line buffer
and the system buffer are saved
(and can
be
obtained via linbuf and sysout described below).
When
either
control-P,
control-D,
or
control-S
control-E,
is
typed,
control-H,
INTERLISP
automatically does a clearbuf[T;T]. (For control-P
and control-S, INTERLISP restores the buffer after
the interaction.
linbuf[flg]
See Appendix 3.)
if fI9=T, value is INTERLISP' 5 line buffer (as a
string) that was saved at last clearbuf[T;T]. If
flg=NIl, clears this internal buffer.
sysbuf[flg]
same as linbuf for system buffer.
If both the system buffer and INTERLISP' s line buffer are empty, the internal
buffers associated with linbuf and sysbuf are not changed by a clearbuf[T;T].
bklinbuf[x]
!
is a string.
buffer to!.
bklinbuf sets INTERLISP' s line
If greater than 160 characters,
first 160 taken.
bksysbuf[x]
! is a string.
bksysbuf sets system buffer to !.
The effect is the same as though the user typed !.
bklinbuf, bksysbuf. linbuf, and sysbuf provide a way of 'undoing' a clearbuf.
Thus if the user wants to ·peek· at various characters in the buffer, he could
perform clearbuf[T;T], examine the buffers via linbuf and sysbuf, and then put
them back.
14.21
radix[n]
Resets output radi~3to I n I w!.th sign in~lc.tor
the' sign of n.
For example,
shown wi ttl, the following
-9 will print as
radic~s':~
radix
printing
10
-9
,
68719476727
-10
i.e. (2t36-9)
-llQ
8
777777777767Q
-8
Value of radix is its last setting.
radix[] gives
current
it.
setting without
changing
Initial
setting is 10.
fltfmt[n]
Sets floating format control to rr (See TENEX JSYB
for
manual
interpretation
of
fltfmt[T]
!l) •
spel:ifies free format (see Section 3).
fl tlrmt is last setting.
set1~ing
Value of
fltfmt[ l returns current
without changing it.
Ini tia1setting is
T.
line1ength[n]
Sets the
lengt~
of the print line for all files.
Value is the former setting of the line length.
Whenever printing an atom would go beuond
length
of
autclmatically
the,
line,
inserted
returns current setting.
a
the
carriage~return
first.
1s
llnelength[ ]
Initial setting is 72.
23----------------------------------------------------------------------------Currently, there is no input radix.
14.22
position[file]
Gives the column number the next character will be
read
from
or
carriage-return,
printed
to,
e.g.
position-O.
after
a
that
Note
position[file] is not the same as sfptr[file]
which gives the position in the" lile, not on the
line.
Line-buffering and CONTROL
In INTERLISP's normal state, characters typed on the teletype (this section
does not apply in any way to input from a tile) are transferred to a line
buffer.
Characters are transmitted from the line buffer to whatever input
function initiated the request (i.e., ~f ~, ~, rstring, or readc)24
onlll when a carriage-return is typed. 26 Until this time, the user can delete
characters one at a time from the input buffer by typing control-A.
characters are echoed preceded by a \.
The
Or, the user can delete the entire line
buffer back to the last carriage-return by typing control-Q, in which case
INTERLISP echoes 11. 26 (If no characters are in the buffer and either control-A
or control-Q is typed, INTERLISP echoes II.)
Note that this line editing is not performed by read or ratom,
but by
INTERLISP, i.e. it does not matter (nor is it necessarily known) which function
24----------------------------~----------------------- -------------------------
peekc is an exception; it returns the character immediately.
26
As mentioned earlier, for calls from read or uread, the characters are also
transmitted whenever the parentheses count reaches o. In this case, if the
second argument to read or uread is NIL, "INTERLISP also outputs a carriagereturn line-feed. --
26
Typing rubout clears the entire input buffer at the time it is tllped,
whereas the action of control-A and control-Q occurs at the time they are
read. Rubout can thus be used to clear type-ahead.
14.23
will
ultimately proce$,s
the characters.
INTERLISP input buffer.,
if the user exec,u,tes
to
they are
still
in, the
function that is currentlu
whether parentheses counting is observed, e.g.
(.P~OGN
(RATOM)'
',t".,·.,
,',
is~the
Note also that it
t~a,~.,:~~t.ermines
.requesting input
only that
(READ»
'"
and, types in A (8 C D) he will have
'
type in the carriage-return t:ollowing ,the right parenthesis before any
action
is
taken,
whereas
if he types
(PROGN (READ) (READ»
he would not.
However, once a carriage-return has been typed, the entire line is 'available'
even if not all of it is processed by the function initiating the request for
input,
i.e.
if
immediately
any
on
characters
the
(PROGN (RATOf1) (READC»
next
are
'left
over',
request
for
they ~illb~
input.
- followed byA B carriage-return
example,
For
will
returned
perform both
operations.
Turning-off Line-buffering
The
function
control[T~,
control
is
.vailable
to
defeat
this ,11ne-buffering.
After
characters are returned to ,the, calling function without line-
buffering as
below.
de~cribed
The function that initiates the request for
input determines how the line is treated:
1. read/urea,d
if the expre,ssion being typed:ls a lis.t, the effect 15 the same as though
control
NIL,
were
parentheses.
i.e.
line-buffering
until
carriage-return
If the expression being typed is not a list, it is returned as
soon as a break or separator chclracter is encountered,,27
27--" - - - - _._
•
-'c~
or, matching
,.
-
-:.~
-."., -
,g. g •
,1
_ .. -
-.'- - . - : - - - - . , - - - - . - - - - - - - , -
~
... -
- . - - - - - - .. -
-:- . . .
(READ) followed
-1;"""-'-." -,~- - - ~ - .... - - _...
An exception to the above occurs when the break or separator chara'cter is a
(,If, or [,'since returning Cit this 'point would leave the line buffer in a
"funny" state. Thus if control is T and (READ) is followed by 'A8C(', the
A8C will not be read until a carriage-return or matching parentheses 1s
encountered. In this ..case, the user could,con~trol-Q the entire:" line, since
all of t'lle 'c'haracters are still ,in the buffer.,
14.24
by ABC space will immediately return ABC. Control-A and control-Q editing are
available on those characters still in the buffer.
Thus, if a program is
performing several reads under control[T], and-the user types NOW IS THE TIME
followed by control-Q, he will delete only TIME since the rest of the line has
already been
transm!~ed
to read and processed.
2. ratom
characters
are
encountered.
returned
as
soon
as
a br~ak' or
separator
character
is
Before then, control-A and control-Qmay be used as with read,
e.g. (RATOH) followed by ABCeontrol-Aspace will return AB.
(RATOH) followed by
(control-A will return ( and type II indicating that control-A was attempted
wi th nothing in tJle buffer,
since the ( is a break character and would
therefore already have been read.
3. reade/peeke
the
character is returned immediately; no line editing is possible.
particu lar.
In
(READC) followed by control-A will read the control-A, (READe)
followed by X will read the X.
control[u]
eliminates
!!=T
INTERLISP's
normal
line-
buffering.
u=NIl
restores line-buffering (normal).
u=O
eliminates
echo
of
being
character
deleted by control-A.
restores echo (normal).
u=1
The
value
of control when !!=T or NIL
previous line-buffering setting,
i.e.
is
its
T or NIL.
When !:!,=O or 1, its value is 1 ts previous echo
setting, 1.e. 0 or 1.
14.25
14.5
Special Functions
sysout[file]
Sa,'es the user' s private memory on file.
Also'
sa,'es the .stacks, so that if a program performs a
sys;out.. the subsequent sysin will continue from
thalt point. e. g.
(PR,OGN (SYSOUT (QUOTE FOO»
will
. cause
HELLO
(SY'SIN (QUOTE FOO»
( full name).
,to
(PRINT (QUOTE HELLO»)
,be'
printed
after
The value of sysout is file
A value of NIL indicates the sysout
was unsuccessf,ul, i.e., either· disk' or computer
error, or user's directory was full.
SlIsout does not saue the state 0/ anu open Jtles.
Whenever the INTERLISP sustem
are not compatible.
sysin[file]
iJ;
reassembled and/or reloaded, old svsout Jiles
restores the state' of
fille.
INTERLISP from a
Value is list[file].
Sysout
If sysin returns NIL,
thelre was a problem in reading the file.
If the
file. was not found or is incompatible (see note
abo've), generates an error, FILE NOT COMPATIBLE.
Stncesystn conttnues tmmedtatelll where susout Le/t all, the onlu wall for a
program to determine whether it is just cominll back. Jrom a svsin or from a
svsout is to test the ualue 0/ ~lsout.
For example,
(CONO «lISTP (SYS()UT (QUOTE FOO») (PRINT (QUOTE HELLO»»
will
cause HEllO to be printed follclwing the sysin, but not when the sysout was
performed.
14.26
14.6
Symbolic File Input
load[file;ldflg:printflg]
Reads
successive
S-expressions
from
evaluates each as it is read,
file
and
until it reads
either NIL. or the single atom STOP. Value is file
(full name).
If printflgaT. load prints "the value of each 8expression: otherwise it does not.
the operation of define, defineg,
ldflg affects
~.
and rpaqq.
While load is operating, dfnflg (Section 8) is
reset to Idflg. 28 Thus, if ldflg=NIl, and a
function is redefined, a message is printed and
the old definition saved.
If ldflg=T,
definition is simply overwritten.
the
function
property
lists
definitions
under
are
the
the old
If Idflg=PROP,
stored
property
on
EXPR.
the
If
ldflg=AllPROP, not only function definitions but
also variables set by
proper~y lists. 29
10adfns[fns;file:ldf19]30
~
and
~
are stored on
permits selective loading of function definitions.
fns is a list of function names, a single function
name,
or
T,
meaning
all
functions
(but
no
28---~~----------~------------------------------------ -------------------------
Using resetvar (Section 5). dfnflg cannot simply be rebound because it 1s
a GLOBAL variable. See Section 18.
29
except when the variable has value NOBIND, in which case it is set to the
indicated value regardless of dfnrls.
80
loadfns was written by J.W. Goodwin.
14.27
var'iabl9s, property values, etc.) .'
file can be
either a compiled or symbolic file, i.e., any file
thillt can be loaded by load.
file is "opene"d and
sCt:lnned ill the manner of load, and every function
definition
found
for
a
function
on
fns
is
I081ded .31 . The interpretation of ldflg is the same
as for load.
loadfns uses skread (page 14.17) and lcskip (a
subfunction of recompile) to skip over undesired
moterial on the file, and so it is very efficient.
The value of loadfns is a list of those functions
loaded plus a list of those functions not found
(if any)
headed by the
atom
NOTFOUND:.
e.g.,
from
using
(FOO FIE (NOTFOUND: FUM».
readfile[file]
Reads successive 8-expressions
r!!~
file
until the single atom STOP is read, or an end
of file encountered.
Value is a list of these 8-
exp.ressions.
~i---------------------------·--"-------------------~--~~----~----------------If a compiled definition is loaded, so are all compiler generated
subfunctions.
Note however if fns specifies entries to a block (see
Section 18) the user must al~.o specify the block itself.
, 14.28
14.7
Symbolic File Output
writefile[x;file:dateflg]
Writes successive S-expressions from ! on file.
If ! is atomic, its value is used.
open, it is opened.
If file is not
If the first expression on !
is the type produced by printdate, or if date fig
is T, • new date expression is written.
If file
is a list, car[file] is used and the file is left
opened.
Otherwise, when ! is finished, a STOP is
printed on file and it is closed.
Value is file.
nlambda, nospread function that performs output[T]
pp[x]
and then calls prettyprint: PP FOO is equivalent
to PRETTVPRINT«FOO»; PP(FOO FIE)
o~
(PP FOO FIE)
is equivalent to PRETTVPRINT«FOO FIE».
Primary output file is restored after printing.
prettyprint[lst]32 33
1st is a list of functions (if atomic, its value
is used).
The definitions of the functions are
printed in a pretty format on the primary output
file. For example,
(FACTORIAL
[LAMBDA (N)
(COND
«ZEROP N)
1)
(T (ITIMES N (FACTORIAL (SUB1 N])
82----------------------------------------------------------------------------The prettyprint package was written by W. Teitelman.
83
prettyprint has a second argument that is T when called from prettydef. In
this case, whenever prettyprint starts a new function, it prints (on the
teletype) the name of that function if more than 30 seconds, (real time)
have elapsed since the last time it printed the name ot a functione
14.29
Note:
prettyprint will operate correctly on fugctions
broken-i~,
that are broken,
advised, or have been compiled with their definitions saved on their
property lists - it prints the: original, pristine' detini tion, but does not
change the current state of the function.
If prettyprint is given an atom
which is not the name ofa function, but has a value, it will prettyprint the
value. 34 Otherwise,prettyprint~. will perform spelling correction.
If
all
A facility for annotating INTERLISP, functions is provided in prettyprint.
Any
fails, prettyprint returns (atom NOT PRINTABLE).
Comment Feature
S-expression beginning with
right margin.
(FACTORIAL
[LAMBDA (N)
(COND
«ZEROP
a
is interpreted as a comment and printed in the
Example:
(a
COMPUTES NI)
(a 0!-1)
N)
1)
(. RECURSIVE DEFINITION:
Nt.NaN-11)
(T
(ITIHES N (FACTORIAL (SUB1 N])
These comments
act~ally
form a peart of the function definition.
Accordingly,.
is defined as an NlAHBDA NOSPREAD function that returns its argument, i.e.
is equivalent to quote.
it
When running an interpreted function, a is entered the
same as any other INTERLISP function.
Therefore, cO,mments should only be
placed where they will not harm the computation, i.e. where a quoted expression
could be placed.
For example, wr"i ting
(ITIHES N (FACTORIAL (SUB1 N»
(~
RECURSIVE DEFINITION»
in the above function
would cause an error when ITIMES attempted to multiply N, N-lt, and RECURSIVE.
34 - - - - - - - - - - - -.~ ,... - - - - - - - ~ ~ - •.• - - - .' - - - - _.. - - - - - -.- - - ... - - - - - - - -." - - - - - - - - - - - - - - ... -- - - - - except when prettyprint is
c~llled
from prettydef.
14.30
For compilation purposes, " is defined as a macro which compiles into no
instructions.
Thus, if you compile a function with comments, and load the
compiled definition into another system, the extra atom and list structures
storage required by the comments will be eliminated.
comment feature is intended to be used.
This is the way the
For more options, see end of this
section.
Comments
are
designed
mainly
for
documenting
Thus
listings.
when
prettypr1nt1ng to the teletype, comments are suppressed and printed as the
string **COMMENT-*.36
Prettydef
prettydef[prettyfns;prettyfile;prettycoms]36
that
are
Used to make
suitable
for
loading
symbolic
which
files
contain
function definitions, variable settings, property
lists, et aI, in a prettyprint format.
The arguments are interpreted as follows:
prettyfns
Is a list of function names.
The
functions
on
the
list
are
prettyprinted
surrounded by a (DEFINEQ ••• ) so that they can be
36----------------------------------------------------------------------------The value of **comment**flg determines the action. If IIrlircomment**flg is
the comment is printed. Otherwise, the value of IIrlircomment**flg is
printed. **comment-.flg is initially set to " **COMMENT** ". The function
~ is provided to prettyprint functions, including their comments, to the
teletype. ~ operates exactly like .I!I!. except it firs,t sets "*comment**flg
to NIL.
NIL,
36
prettydef actually has two additional arguments for use by the system.
14.31
loaded with' load.
If pre'ttYfns is atomic' (the
preferred usage h i tstop level value is used as
the list of function names, and an'.!J!.!9.!l 87 will
alsl!) be written which will' set that atom to the
lis't of functions when the file
is' loaded.
~~t
written
expression
will
also
be
A
which
inft!)rms the user of the named atom or list of
funlctions when the file is subsequently loaded. .
prettyfile
is 'the name of the file on which the out'put is to
be ,,,ritten.
The following options exist:
prettyfile=NIL
The primary output file is used.
prettyfile atomic
The file is opened if not already open,
and becomes primary output file.
is
closed
at
end
of
prettydef
File
and
primary output file is restored.
prettyfile a list
Car of the list is assumed to be the
file name, and is opened if not already
open.
The file is left open at end of
prettydef.
37----------------------------------------------------------------------------rpaqq and !:J!!.q are like se1~ and setq, except they set the top level
value.
See Section 5.
14.32
prettycoms
Is a list of commands interpreted as described
below.
If prettycoms is atomic (the preferred
usage), its top level value is used and an rpaqq
is written which will set that atom to the list of
commands when the file is subsequently loaded,
exactly as with prettyfns.
These commands are used to save on the output file top level bindings of
variables,
property lists of atoms,
miscellaneous
I~TERLISP
evaluated upon loading. arrays, and advised functions.
forms
to
be
It also provides for
evaluation of forms at ouput time.
The interpretation of each command in the command list is as follows:
1.
if atomic, an
this atom when
Z.
I
~
th~
is written which will restore the top level value of
file is loaded.
(PROP propname atom 1 ••• atomn ) an appropriate deflist will be written
which will restore the value of propname for each atom! when the file is
loaded.
If propname=All,
the values of all user properties
(on
the
property list of each atom i ) are saved. a8 If propname is a li'st, deflist's
will be written for each property on that list.
3.
(ARRAY atom 1 ••• atomn ), each atom following ARRAY should have an array as
its value. An appropriate expression Will be written which will set the
atom to an array of exactly the same size, type, and contents upon loading.
38----------------------------------------------------------------------------sysprops is a list of properties used by system functions. Only properties
not on that list are dumped when the ALL option is used.
14.33
4.
(P .•• ), each S-expression following P will be printed on the output file,
and consequently evaluated when the file is loaded.
5.
(E .,.. ),
each form following E will be evaluated at output time,
i.8.,
when prettydef reaches this command.
6.
(FNS fn 1 ... fn m), a defineq is written with the definitions of fn l ••• fn m
exactly as though (fn 1 ••• fn m) where the first argument to pr~ttydef. For
example, suppose the user ,,,anted to set some variables or perform some
computations in a file be/ore defining functions, he would then write the
definitions
using
the
FNS
command
instead of
the
first
argument
to
prettydef.
7.
(VARS var 1 .. '. var n ), for eilch var i , an expression will be written which
wi 11 set its top level valUEt when the file is loaded. If Y!!:.i is atomic,
Y!!.i will be set to the
prettydefed. i.e.
non-atomic,
tO~I-level
value it had at the time the file was
(RPAQQ vari top-level-value) is written.
it
(FOO (APPEND FIE FUM»
is
or
int,erpreted
(F~)()
as
(var
If Y!!:i is
form).
e.g.
(QUOTE (FOOl FOOZ FOO3»). In this case the
expression (RPAQ var form) is written.
8.
fn l .•• fn m), for each fn n • an appropriate expression will be'
wri tten which will reinstate the function to· its advised state when the
(ADVISE
file is loaded.
9.
(ADVICE fn 1 ... fn m,), for E!ach fn i , will write a deflist which will put
the advice back on the property list of the function.
use readvise to reactivate the advice.
The user can then
See Section 19.
10. (BLOCKS block 1 ... block n ) for each block i , a declare expression will be
wri tten which the block comp:lle functions interpret as block declarations.
See Section 18.
14.34
com 1 ... comn ) , each of the
interpreted as a prettydef command.
11. (COMS
commands
com t
~
••
comn
will
be
12. (AOOVARS (var t • lstt) ... (var n • lst n » For each var i , the effect is the
same as (RPAQ var i (UNION lst i var i », i.e. each element of lst i not a
member of var i (at load time) is added to it. Y!!!i can initially be
NOBINO, in which case it is first set to NIL.
13. (USERMACROS atom t ... atomn ), each atom i is the name of a user edit macro.
USERMACROS writes expressions for adding the definitions to usermacros and
the names to the appropriate spelling lists.
(USERHACROS) will save all
user edit macros.
14. (IFPROP propname atom t ••• atomn ) same as PROP command, except that only
non-NIL property values are saved. For example, if FOOl has property PROPt
and
PROPl,
FOOl
has PROP3,
and FOO3" has property PROP1
and
PROP3,
(IFPROP (PROPIPROPl PROP3) FOOl FOOl FOO3) will save only those 5 property
values.
15. (COHPROP propname atom, •.. atomn) same as PROP command, except that the
corresponding deflist expression will also be evaluated when the file is
compiled.
16. (COHPROP*
Useful fot outputting MACROs.
propname atom, ..• atomn) ,
same as COMPROP except
that
the
corresponding deflist expressions are not copied to the compiled file by
tcompl, bcompl. recompile, or brecompile.
17. (PO ... ),
like P except that the corresponding S-expressions are also
printed as DECLARE expressions, and thus will be evaluated when the file is
compiled.
In other words,
(PO (OEFLIST (QUOTE --) (QUOTE propname»
essentially equivalent to (COHPROP propname --).
14.35
1s
In each of the commands described above, if the atom * follows the command
type, the form following the *, i.e.,
~
of the command, is evaluated and
its value used in executing the command, e.g., (FNS * (APPEND FNSI fNS2».89
*
Note that (COMS
form) provide,s a way of computing what should be done by
prettydef.
New prettydef conunands can be defined via prettymacros (see page 14.40).
If
prettydef
Qn
is
pret tymacros,
spelling list.
given
it
a
command not
attempts
one of the
above,
spelling correction40 using
and not
defined
prettycomsplst
as
a
If successful, the corrected version of prettycoms is written
(again) on the output file. 41 If unsuccessful, prettydef generates an error,
BAD PRETTYCOH.
39-------------------------------'---------------------------------------------Except for the PROP, IFPROP, COMPROP, and COMPROP* commands, in which case
the * must follow the property name, e.g., (PROP MACRO * FOOHACROS).
40
unless dwimflg=NIl. See Section 17.
41
since at this point, the uncorrected prettycoms would already have been
printed on the output file. When the file is loaded, this will result in
prettycoms being reset, and a message printed, e.g. (FOOVARS RESET). The
value of FOOVARS would then be the corrected version.
14.36
Example:
(FOOl FOOZ F003»
(PROP MACRO FOOt FOO2) (P (MOVD (QUOTE FOOl)
(QUOTE FIE1]
~PRETTYOEF(FOOFNS Foo FOOVARS)
~SET(FOOFNS
~SET(FOOVARS(FIE
would create a file FOO containing
1.
A message
which
prints
the
time and date
the file
was made
(done
automatically)
2.
OEFINEQ followed by the definitions of FOOl, FOO2. and FOOl
3.
(PRINT (QUOTE FOOFNS) T)
4.
(RPAQQ FOOFNS (FOOt Foo3 FOOl»
5.
(PRINT (QUOTE FooVARS) T)
6.
(RPAQQ FOOVARS (FIE ... )
7.
(RPAQQ FIE value of fie)
8.
(OEFLIST (QUOTE «FOOl propvalue) (FOO2 propvalue») '(QUOTE MACRO»
9.
(MOVO (QUOTE FOOl) (QUOTE FIE1»
10. STOP
printfns[x]
~
is a list of functions.
and
prettyprints
the
printfns prints defineq
functions.
Used
by
prettydef, i.e. command (FNS • FOO) is equivalent
to command (E (PRINTFNS FOO».
printdate[ffle;changes]
prints the expression at beginning of prettydefed
files that upon loading types the time and date
the file was made, and stores this time and date
on the property list' of file under the property
FILEDATE.
tab[pos;minspaces;file]
changes is for use by the file package.
performs appropriate number of spaces to move to
14.l7
position pos.
minspaces
I
indicates the minimum
number of spaces to be printed by tab, i.e., it is
intended to be small number (if NIL, 1 is used).
Thus, if position + minspaces is greater than pos,
tab does a terpri and then spaces[pos].
endfile[file]
Prints STOP on file and closes it.
printdef[expr;left;def]
prints the expression expr on the primary output
fil '9 in a pretty format.
margin
margin).
(linelength
left is the left hand
determines
the
right
hand
2 is used if left=NIL.
defllT means expr is a function definition, or a
piece of one,
i.e.
prettyprint
printdef[getd[fn];NIL;T].
is essentially
If def=NIL, no special
action will be taken for LAMBDA's, PROG's, CONO's,
cOlDlllents, CLISP, etc.
der is NIL when prettydef
calls prettyprint to print variables and property
lis1;S, and when printdef is called from the editor
via the command PPV.
Special Prettyprint Controls
All variables described below, i.e., Irpars. firstcol, et aI, are globalvars.
see Section 18.
Therefore, if they are to be changed, they must be reset, not
rebound.
Irpars
controls the number of right parentheses necessary
for square bracketing to occur.
brackets are used.
14.38
If Irpars-NIL, no
Irpars is initialized to 4.
linelength[n]
determines the position of the right margin for
prettyprint.
firstcol
is the starting column for comments.
setting is 48.
line length.
, • I
Initial
Comments run between firstcol and
If a word in a comment ends with a
and is not on the list abbrevlst, and the
position is greater than halfway between firstcol
and linelength,
begins on
encoun~ered
the next word
a new line.
in
Also,
the comment
if
a
list
is
in a comment, and the position is
greater than halfway. the list begins on a new
line.
prettylcom
If
a. comment
pretty~com
is
bigger
in size,
(using
count)
than
it is printed starting at
column 10, instead of firstcol.
prettylcom is
initialized to 14 (arrived at empirically).
widepaper[flg]
widepaper[ T] sets linelength to 120, firstcol to
80 and prettylcom to 28.
This is a useful setting
for prettyprinting files to be listed on wide
paper.
w1depaper[] restores these parameters to
their 1ni tial values.
The value of widepaper is
its previous setting.
commentflg
If £!! of an expression is
~
to commentflg, the
expression is treated as a comment.
commentflg is
initialized to ,.
prettyflg
If pre·ttyflg is NIL, printdef uses prin2 instead
14.39
of prettyprinting.
This is useful for producing a
fast symbolic dump (e.g. when TENEX is very slow.)
Note that the file loads the same as if it were
prettyprinted.
clispifyprettyflg
prettyflg is initially set to T.
if T, causes prettyprint to clispify each function
definition
before
printing.
See
Section
23.
clispifyprettyflg is initially NIL.
prettymacros
Is an assoc-type list for defining substitution
macros
for
prettydef.
If
(FOO (X Y) • coms)
app1aars on prettymacros, then (FOO A B) appearing
in the third argument to prettydef will cause A to
be substituted for X and B for Y throughout £2!!!!.
( i.11t ., cddr of the, macro) • and then £2!!!! treated
as
41
list of commands for prettydef.
A comment of this form causes
(* E x)
pre1~typrint
com~ent
time,
e.g.,
~
to be evaluated at
(- E (RADIX 8»
as
a
in a function. containing octal numbers can
be used to change the
readable printout.
radix to
produce
more
The comment is also printed.
Converting Conunents to Lower CasEI
This
section
is
for users operating on terminals without
lower case who
nevertheless would like their cOlnments to be converted to lower case ror more
readable line-printer listings.
Users with lower-case terminals can skip to
the File Package sections (as they can type comments directly in lower case).
14.40
If the second atom in a comment 15 XX, the text of
the comment is converted to lower case so that it
looks like English instead of LISP
(see next
page) •
The output on the next page illustrates the, result of a lower casing operation.
Before this function 'was prettydefed, all comments consisted of upper case
atoms, e.g., the first comment was
(*
XX INTERPRETS A SINGLE COMMAND). Note
that comments are converted onlu when they are actually writte.n to a file by
prettydef.
The algorithm for conversion to lower case is the following: If the first
character in an atom is t, do not change the atom (but remove the t).
first character is Xt convert the atom to lower' case. 42
INTERLISP word,44 do not change it.
If the
If the atom43 is an
Otherwise, convert the atom to lower case.
Conversion only affects the upper case alphabet, i.e., atoms already converted
to
lower case are not changed if the comment is converted again.
converting.,
the
first
character in the comment and the
following each period are left capitalized.
first
When
character
After conversion, the comment is
physically modified to be the lower case text .minus the XX flag, so that
conversion is thus only performed once (unless the user edits the comment
inserting additional upper case text and another XX flag).
42--U;;;-;~;~-~;;;-ii-;;-i-i;-~h;-;;~;;;-~h;;;~;;;:-----------------.----------48
minus any trailing punctuation marks.
44
i.e., is a bound or free variable for the function containing the comment,
or has a top level value, or is a defined function, or has a non-NIL
property list.
14.41
(BREAKCOM
[LAMBDA (BRKCOH BRKFLG}
(PROG (BRKZ)
TOP (SELECTQ
BRKCOH
[t (RETEVAL (QUOTE BREAK1)
( QUOTE It ERROR] ]
(GO
(~ Interprets a
single command.)
(~ Evaluate BRKEXP
unless already evaluated,
print value, and exit.)
(BREAKCOHI BRKE)(P BRKCOM NIL BRKVALUE)
(BREAKEXIT»
(OK
c. Evaluate BRKEXP,
unless already evaluated,
do NOT print value,
and exit.)
CBREAKCOH 1 BRKE)(P BRKCOM BRKVALUE BRKVALUE)
(BREAKEXIT T»
(tWGO
(* Same as GO except
never saves evaluation
on his tory. )
.( BREAKCOM t. BRKE)tP BRKCOM T BRKVALUE)
(B~EAKEXIT»
.
(RETURN
(~ User will type in expression to be evaluated and
returned as value of BREAK. Otherwise same as GO.)
(BREAKC0t11 [SETQBRKZ (COND
(BRKCOHS (CAR BRKCOHS»
(T (LISPXREAD T]
(QUOTE RETURN)
NIL NIL (LIST (QUOTE RETURN)
BRKZ»
(BREAKEXIT»
(EVAL
(* Evaluate BRKEXP but
do not exit from BREAK.)
(BREAKCOHI BRKEXP BRKCOM)
(COND
(BRKFLG (BREAKZ)
(PRINt BRKFN T)
(PRINt (QUOTE • EVALUATED
T»)
(SETO 'VALUE (CAR BRKVALUE»
)
14.42
(. For user's benefit.)
lease 1st
Words on lcaselst will always be converted to
lower case.
lcaselst is initialized to contain
words which
are
INTERLISP
functions
but
also
appear frequently in comments as English words.
e.g. AND, EVERY, GET, GO, LAST, LENGTH, LIST, etc.
Thus, in the example on the previous page, not was
written as tHOT, and GO as tGO in order that they
might be left in upper case.
ucaselst
words on ucaselst (that do not appear on lcaselst)
will
be
left . in
upper
case.
ucaselst
is
initialized to NIL.
abbrevlst
abbrevlst
is
used
to
abbreviations and words
distinguish
that
end
in
between
periods.
Normally, words that end in periods and occur more
than halfway to the right margin cause carriage
returns.
Furthermore,
during
conversion
to
lowercase, words ending in periods, except for
those on abbrevlst, cause the first character in
the next word to be capitalized.
abbrevlst is
initialized· to the upper and lower case forms of
ETC. I.E. and E.G.
l-case[x;flg]
value is lower case version of!.
the first letter is capitalized,
l-case[FOO;T]
= Foo,
l-case[FOO]
If fIg is T,
e~g.
= foo.
string, the value of I-case is also a
If! is a
~tring,
l-case[-FILE NOT FOUND-:T] • -File not found-.
u-case[x]
Similar to I-case
14.43
e.g.
14.8
File Package46
This section describes a set of functions and conventions for facilitating the
bookkeeping involved with working in a large system consisting of many symbolic
files and their compiled counter'parts.
The file package keeps track of which
files have been in somo way modified and need to be dumped, which files havo
been dumped,
but still need to be listed and/or recompiled. The functions
described below comprise a coherent package for eliminating this burden from
the user.
They require that for each file, the first argument to prettydet,
(if any), be an atom of the forllll fileFNS.and the third argument, (if any). be
fileVARS
where
file
is
the
name
of
the
. file,
e.g.
prettydef[FOOFNS;FOO;FOOVARS].46
The functions load, editf,
edit~!,
tcompl, recompile, bcompl,
brecompile, and
DWIM interact with the function:s and global variables in the file package as
follows.
Whenever load is callEld, its argument is added to the list filelst,
and the property FILE, value {fileFNS fileVARS). is added to the property list
of the file name. 47 This property value is used to determine whether or not the
file has been modified since thEt last time it was loaded or dumped.
Whenever
the user calls editf and change.s a function,. filelst is searched to find the
45------------------------------··------------------------~--------------------The file package was written by W. Teitelman.
It can be disabled by
setting filepkgflg to NIL.
46
47
file
can
contain
a
suffix
and/or
version
number,
e.g.
PRETTYOEF(FOOFNS FOO.TEH;3 F(~VARS) is acceptable. The essential point is
that the FNS and VARS be computable from the name of the file.
The name added to filelst has the version number and directory field
removed, if any. fileFNS and fileVARS are constructed using only the name
field, i.e., if the user porforms load[FNSIVARS.
filefnslst[file]
returns a list of the functions in file,
specified by fileFNS and fileVARS.
i. e.
fllefnslst
knows about prettymacros.
newfile2[name;coms;type]
£Q!!!! is a list of prettydef commands,
~
is
usually FNS or VARS but may be BLOCKS, ARRAYS,
etc. or the name of any other prettydef command.
If n!!!=NIL,
newfile2
elements of type!l2!.
returns
a
list
of
all
(filefnslst and bcompl and
brecompile use this option.)
If !!.!!!!!=T, newfile2 returns T if there are anll
elements- of type!l2!.
(makefile uses this option
to determine whether the file contains any FNS,
and therefore should be compiled,
whether
it contains
whether
to
call
any BLOCKS,
and
to
if so,
determine
bcompl/brecompile
or
tcompl/recompile.)
Otherwise,
newfile2
returns
-contained-
in~.
(whereis uses newfl1e2 in
this way.)
14.49
T
if
n!m!
is
•
If the user often employs
•
•
their expansion by the various parts of
prett~macros,
the system that need to interr'ogate files can result in a large number of
conses and garbage collections.
If the user could inform the file package as
to what his various prettymacros: actually produce, this expansion would not be
necessary.
For example, the user may have a macro called GRAMMARS which dumps
various property list but no functions.
Thus, the file package could ignore
this conunand when seeking information about FNS.
The user can supply this
information by putting on the pr'operty list of the prettymacro, e.g. GRAMMARS,
under the property PRETTYTYPE, 4)6 a function (or LAMBDA expression)
arguments, com and
VARS,
etc.
BLOCKS.
~,
where
~
is a prettydef command, and
function
is FNS,
The resul t of applying the function to these arguments
should be a list of those elements of type 1l2! contained in £2m.
the
~
of two
corresponding
to
GRAMMARS
For example,
might
be
( LAMBDA( COM TYPE)( AND (EQ (CAR C()M) TYPE)( EQ TYPE (QUOTE GRAMMARS» (CO'R COM». 67
Currently, the file package knows about two "types": functions and variables.
As described in footnote on pa.ge 14.45, whenver a function or variable is
changed,
it
is
added
to
changedfnslst
or
changedvarslst
respectively.
Updatefiles operates by mapping down filelst and using newfile2 to determine if
the
corresponding file contain:s any of the functions on changedfnslst or
changedvarslst.
The user can tell the file package about other types by adding
appropriate entries to prettytypelst.
Each element of prettytypelst is a list
of the form (name-of-changedlist, type string), where string is optional.
For
56------------------------------··---------------------------------------------If noth ing appears on property PRETTYTYPE, the command is expanded as
before.
67
Note that since the function is given the entire command as an argument,
the same function could be used for several different types.
14.50
example,
prettytypelst
(CHANGEOVARSlST VARS».68
is
If
initially
the
user
«CHANGEDFNSlST FNS -functions-)
adds
(CHANGEDGRAMlST GRAMMARS)
to
prettytypelst, then updatefiles will know to move elements on changedgramlst to
the FILE property'for the files that contain them. 69
68----------------------------------------------------------------------------If string is supplied, files? will inform the user if any elements remain
on the changed list after updatefiles has completed. Similarly, makefiles
will warn the user that some elements of this type are not going to be
dumped in the event that it could not find the file to which they belonged.
69
It is the user I s responsibility to see that elements are added to the
changed list in the first place.
14.51
Index for Section 14
Page
Numbers
ABBREVlST (prettydef variable/parameter) ••......
address~ab 1e files
..........•.••..•.•.•••..••••.•
ADDVARS (prettydef command) ......••••••••••••.••
ADVICE (prettydef command) ••.•...•.•.••.••.•••••
ADVISE (prettydef command) .........•.•••.•••••.•
ALL (use in prettydef PROP command) •••••••••••••
AllPROP (as argument to load) •..•...••••••••••.•
ARRAY (prettydef command) ...•.•......•••.•.•••••
BAD PRETTYCOH (prettydef error message) •••••••••
BCOHPl[FIlES;CFIlE;NOBlOCKSFLG] ••..••.••••.•.••.
bell (typed by system) •.•.••.•••.•••••••••.•••.•
BKlINBUf[X] SUBR ........••.••.••••.••.•••.•.•••.
BKSYSBUF[X] SUBR ............•••.•.••..••••.•.•••
block declarations ......•.•.•••.•.••.••.....••••
BLOCKS (prettydef command) .•....•.•..•.•..•.••••
break characters .......•.••..••.......•••••.••••
BRECOMPILE[FILES;CFILE;FNS;COREFLG;NOBLOCKSFLG]
C (makefi 1e option) ......••.....••••.••..••••..•
carriage-return .......•..•.•......••.•.•...•.•••
CHANGEOFNSLST (file package variable/parameter) •
CHANGEOVARSlST (file package variable/parameter) ..
CLEANUP[FIlES] NL- ........•......••••••.••..••.•
CLEARBUF[FILE;FLG] SUBR •••••••••••••••••••••••••
CLISP
.111
•••••••••••••••••••••••••••••••••••••••••
ClISPIFY[X;l] ..............•.•..•••••••.••..••••
ClISPIFY (makefile option) •..•.•..•••••••••••.••
ClISPIFYPRETTYFLG (prettydef variable/parameter) .•
CLOSEAll[] SUBR ...........•.•.•••••••••.••..•.••
CLOSEF[FILE] SUBR .............•.•••.••.•••.•••••
COMHENTFLG (prettydef variable/parameter) •.••••.
comments (in listings) ...••.•.•..•.•.••••••••••.
COMPllEFIlES[FIlES] NL- •••••••••••••••••••••••••
COMPROP (prettydef command) •....•••••••.••••••••
COHPROP* (prettydef command) ••••.••••.••••..••.•
COMS (prettydef command) •.....••.•••••.•.•.•••.•
CONTROl[U] SUBR ......•..•...•••••••••.•.••..••.•
control-A ...................................... .
control-D ...................................... .
control-E .......... s • • • • • • • •
control-F ........................................ .
control-H ....................................... .
control-O ........................................ .
control-P ....................................... .
control-Q ....................................... .
control-S ..................
DECLARE " ......................................... .
I1 . . . . . . . . . . . . . . . . . . . .
III
.................... .
DEFLIST[l;PROP] ...........•...•.••• ~ •••••.••....
DFNFLG (system variable/parameter) ••..••.•.••.••
OW 1M
•...•
It
DWIMIFY[X;L]
••••••••••••••••••••••••••••••••••••••
........•....•••••••••••••••••••
II
•••
E (prettydef command) .......•••••••••••..••.••.•
E (in a floating point number) •...••..•••.••.•..
E (u s e inc omme n t s ) . . • . . . • • • • • • • • . • • • • . • • • • . . . • •
EDITF[X] NL*
......................... : ...•......•
EDITV[EOITVX] NL- •••••••••••••••••••••••••••••••
END OF FILE (error message) .••••••••.••••••••.••
INDEX.14.1
14.39,43
14.5
14.~5
14.34
14.34
14.33
14.27
14.33
14.36
14.44,46
14.20
14.21
14.21.47
14.34
14.34
14 . 12 -15 , 19, 24
14.44.46-48
14.46
14.10-11,13,15-19,23
14.45,50
14.45,50
14.45,48
14.21
14.46
14.40,46
14.46
14.40,46
14.4
14.4
14.39
14.30-31,40
14.48
14.35
14.35
14.35
14.11,14,23
14.10,12,14-15,23,25
14.21
14.21
14.2
14.21
14.20
14.20-21
14.10-12,14-15,23,25
14.21
14.34-35
14.33
14.27
14.44
,14.46
14.34
14.11
14.40
14.44
14.44
14.6,10
Page
Numbers
end-of -1 ina
.................................... .
ENOFILE[Y]
•...•.. "' •••••••••••••••••.••••••••••••
ESCAPE[FLG] SUBR ..•....•.••...•..•••••••..••. ~ •.
escape character .•.•.•• ~ ••••••••••••••••••••••••
EXPR (property name) ••••••••••••••••••••••••••••
FAST (makefile option) ••••••••••••••••••••••••••
fast symbolic dump .•....••••••••••••••••••••••••
FILE (property name) .•.•••••••••••••••••••••••••
f1 Ie names
FILE
FILE
FILE
file
..............................•.......
NOT COMPATIBLE (error message) •••••••••••••
NOT FOUND (error message) •••.•••••.••••••••
NOT OPEN (error message) •••••••••••••••••••
package .•..•...••.•••.•••••••••••••••••••••
file pointer
.....
III
••••••••••••••••••••••••••••••
FILE WON'T OPEN (error message)
FIlECREATED
..............
41
eo • •
.••••••• o.~ ............ .
FILEOATE (property name)
fileFNS
.••••••••••••••••
....• ,. ....••..••• ,. •••••••••••••••
••••••••••••••••••••••••••
FILEFNSLST[FILE] .........••..••..•••..•••••••.••
FILEGROUP (property name) .•........••.••••••••••
FILELST (file package variable/parameter) ••.••••
FILEPKGFLG (file package variable/parameter)
FILEPOS[X;FILE;START;END;SKIP;TAIL] •••••••••••••
files .......... "............................... .
FIlES?[ ] ....................................... .
FILETYPE (property name)
fileVARS
•••.••••.•••.•••••••••••
....................................... .
FIRSTCOL (prettydef variable/parameter) •••••••••
floating point numbers •••••••••••••..••.••••••••
FLTFMT[N] SUBR ... ~ .•..••••• ~ •••••••.•••••.•.••••
FNS (prettydef command) .••••••••••••••••••••••••
form - r e e d
. . . . •. •••. •. . •. •••••••••••••e
• • • • • • • • e •
GETBRK[] SUBR .• ~ ........••..•.•..••••••..••..•••
GETSEPR[] SUBR .......•..••.••••••...••.•••••••••
GLOBALVARS (system variable/parameter) ••••••••••
GTJFN[FILE;EXT;V;FLAGS] ..•..••.•••••.•••.•••...•
IF PROP (prettydef command) ••••••••••••••••••••••
INFILE[FILE] SUBR ...•.•.••••••••.••.••••••••••••
INFILEP[FILE] BUBR ..•...••..•••••••••••.••••..••
INPUT[FILE] SUBR ...•.•..••..••.••.•.••••••.••••.
input buffer
.................
input functions
input/output
0
••••••••••••••••••
...••...••.••••••••••••••••••••••
................................... .
input/output control functions
••.•••••••••••••••
IOFILE[FILE] SUBR ....•.•••.••.••.••..••.••••.•.•
IS A COMPILED FILE AND CANNOT BE DUMPED.
(error message) ••.••••.••••••••••••••••••.•
JF N .•.••••••••••••••••••••••••••••••••••••••••••
JFNS[ JFN ;AC3]
.•.•••.•••••••••••
EX .14.3
14.22,39
14.16
14.47
14.45,47
14.11
,14.27,44
14.27-28
14.43
14.40-43
14.45-48
14.45,47-48,~1
14.38
14.6
14.49-50
14.27
14.46
14.30
14.45-46,48
14.45-48
14.11-12
14.11,18
14.8
14.1
14.3-5,8
14.8
14.2,6-7
14.3-4
14.1
14.20
14.18-20 '
14.34
14.11,23-24
14.35
14.15.25
14.23
14.29
14.31
14.38
14.36
14.31-38,40,44,46
14.33-37
14.39-40,46
14.39
14.36,40,49-50
14.29
14.46
14.50
14.45,50
14.1-2,4,10
14.1,4,18
14.18-19
14.18-19
14.19
14.19
14.29,37,44,46
14.38-39
Page
Numbers
PRINTFNS[X]
.•.........•••.••.••••••••.••••••••..
pr in t leve 1
........................... . ,......... .
PRINTLEVEL[N] SUBR .•...•.•••.••.•••
PROP (prettydef command) ••••••••••••••••••••••••
Q (following a number) ••••••••••••••••••••••••••
QUIT (tenex command) •.••••••••••••••••••••••••••
RADIX[N] SUBR .••.••..••..••.••••••••.••••..•••.•
RATEST[X] SUBR •.•.••.•..•••••.••••.••.••.•••.•••
RATOM[FILE] SUBR ..•.•.•..•.•••••••....•••.•....•
0
RATOMS[A;FN]
••••••••••••
••••••••••••••••••••••••••••••••••••
RC (makefile option) .•••••••••••••••••••• ~ ••••••
READ[FILE;FLG) SUBR •••••••••••••••••••••••••••••
READC[FILE] SUBR .•...•..•.•••••••••.••...•.•••..
READFILE[FILE] ..........•••••••.••••••••••••••••
READLINE[LINE;LISPXFLG] .•..••.•.••••.••••.•••• ~.
READP[FILE] SUBR ...•....•..••••.••••..••.•••••••
READVISE[X] NL* ...........•..•..•••.•....•...•••
RECOMPILE[PFILE;CFILE;FNS;COREFLG] .•••••••.•••••
(REDEFINED) (typed by system) •••••••••••••••••••
RLJFN[ JFN]
........•••••..••.•••••••.• • ~ .•...•....
RPAQ[RPAQX;RPAQY] NL •.•.•.••.••••••••••.•...•••.
RPAQQ[X;Y] NL ......•••..•.•.•••.•••..•.••.•••...
RSTRING[] SUBR ....•••••••••••••••••••••..•.•••••
rubout
..........................
0
•••••••••••••••
searching files ...•....••••••••••••••.••••.•.•••
separator characters ..•••••• ~ •••••••••••••••••••
SETBRK[LST;FLG] SUBR ..•.•••••
SETSEPR[LST;FLG] SUBR ..•••••..••••••.•••••.•.•..
SFPTR[FILE;ADORESS] SUBR .•••.•••.•••..••.•••....
SKREAD[FILE;REREADSTRING] .•..•....•....•.•..•.••
0
space
••••••••••••••••••
...........•..•••...•••••.•••••..••••••••••
SPACES[N;FILE] SUBR ......•..••.....••.•••••••.••
square brackets (inserted by prettyprint) •••••••
STOP (at the end of a file) •••••••••••••••••••••
strings
...................................
$
•••••
STRPOS[X;Y;START;SKIP;ANCHOR;TAIL] ••.•.••...•••.
SUBSYS[FILE/FORK;INCOHFILE:OUTCOHFILE;
ENTRYPOINTFLG] ••...•••.•••••••••••••••.•.•
symbol ic fi Ie input •.•.•.•••••.••••••••••••••..•
symbolic file output .••.••.•••••••••••••••••••••
SYSBUF[FLG] SUBR .......••••.•••.••••.•••••••..••
SYSFILES (system variable/parameter) .•••••••••••
SYSIN[FILE] SUBR ........•.•.•...•.••••••••••••••
S YSOUT[ FILE] EXPR •.•.•.....•.•...•...••.•••••••.
SYSPROPS (prettydef variable/parameter) .••••••••
tab
............... ,. ............................ .
TAB[POS;MINSPACES;fILE] •••••••.••••••••••••.••.•
TCOMPL[FILES] .•...•.••...•.•..•••••..•••••••••.•
teletype
....................................... .
••••••••••••••••••••••••••••••••••• e ••••••
TENEX
...•••••.••••••••••••••••••••••••••••••••••
TERPRI[FILE] SUBR
U - CASE[ X]
.......•....•.......•....•.....
..•••..•...••••.•••••••••••••••••••••••
UCASELST (prettydef variable/parameter) •••••••••
UPDATEFILES[] •.••. ~ .••••...•••••.•••••••••••••••
UREAD[FILE;FLG] SUBR .....•••.••••.•.••••••••••••
USERMACROS (editor variable/parameter) ••••••••••
INDEX. 14 .4
14.37
14.19-20
14.19
14.33,36
14.11,18,22
14.48
14.11,18,22
14.14
14.11-13,25
14.12
14.46
14.10-11,24
14.14,25
14.28
14.16-17
14.16
14.34
14.44,46,48
14.27
14.9
14.27,32
14.27,32-33
14.12
14.23
14.7
14.12-15,19,24
14.12-13,15,19
14.12-13,15,19
14.6-7.23
14.17-18,28
14.13
14.19
14.38
14.27-29,38
\14.11
14.7
14.48
14.27-28
14.29-38
14.21
14.49
14~26
14.21,26
14.33
14.13
14.37
14.44,46
14.1,4,10-11,16,20,23,
31
14.2-4,6-8,40
14.19
14.43
14.43
14.45,50-51
14.11-12,15,24
14.35
Page
Numbers
USERMACROS (prettydef cOllumlnd) ••••••••••••••••••
VARS (prettydef command) ....•.••.••.•.••••.••••.
version numbers ......•••••••••••••••••••••••••••
14.35
14.34
14.2
14.48
WHEREI-S[X]
••••••••••••••••••••••••••••••••••••••
WIDEPAPER[FLG] .........••...•.•.••••..•..•••...• 14.39
WRITEFIlE[X;FILE;OATEFLG] ......•..••............ 14.29
II
14.11-14,19
(followed by a number) .•••••••••••••.••••••••• 14.19
1# (typed by system)
..•..••••••••••••••••••••••• 14.10,23,25
IRPARS (prettydef variable/parameter) •••••••••.• 14.38
S (alt-mode) ...................
14.2
" (escape character) ...•.••••••••••••••••••••••• 14.10-14,18-19,25
" (use 1n comments) ...•...•.•••••••••••.•••.••••• 14.41
"" (use 1n commen ts) .•...•••.•••••••••.••••••••• 14.41
& (typed by system) .......••.••.•••.••.•...••••• 14.19
(
14.13
)
14.13
lIr (u 5 e .inc omme n t 5 ) •••••..••••••••••••••••••••••• 14.30,39
lIr (use in prettydef command) .•.....•••..•.•••••• 14.36
lIrllrCOMMENT-* (typed by system) •.•••.••••.••.•.•.• 14.31
lIr*COMMENT**FlG (prettydef variable/parameter)
14.31
-- (typed by system) .........•••••••.•••.••••••• 14.20
14.13
... (typed by system)
14.17
[
14.13
[,] (inserted by prettypr1nt) •••••••.••.•.•••••• 14.38
\ (typed by system) .•..• ~ •••••••••••••••••••••••. 14.10,23
]
14.13,16
t (use in comments)
14.41
*
46 • • • • • • • • • • • • • • • •
•••••••••••••••••••••••
4'
•••••••••••••••••••••••
INDEX. 14 .5
SECTION 15
DEBUGGING - THE BREAK PACKAG£l
15.1
Debugging Facilities
Debugging a collection of LISP functions involves isolating problems within
particular functions and/or determining when and where incorrect data are being
generated and transmitted.
In the INTERLISP system, there are three facilities
which allow the user to (temporarily) modify selected function definitions so
that he can follow the flow of control in his programs,
debugging information.
package.
and obtain this
These three facilities together are called the break
All three redefine functions in terms of a system function, break1
described below.
Break modifies the definition of its argument, a function fn·, so that if a
break· condition (defined by the user) is satisfied, the process is halted
temporarily on a call to fn.
The user can then interrogate the state of the
machine, perform any computation •. and continue or return from the call.
Trace modifies a definition of a function fn so that whenever fn is. called, its
arguments (or some other values specified by the user) are printed.
value of fn is computed it is printed also.
When the
(l.!:!£! is a special case of
break) .
i---T~;-b;;;k-~;~k;;;-;;;-;;i;;;~-b;-W:-T;i;;i;;~:-----------------------------
15.1
Breakin allows the user to insert a breakpoint inside an expression defining a
function.
the user)
When the breakpoint i.s reached and if a break condition (defined by
is satisfied,
a temporary halt occurs and the user can again
investigate the state of the computation.
The following two examples illustrate these facilities.
the user traces the function fa'ctorial.
In the first example,
trace redefines factorial so that it
calls break1 in such a way that it prints some information, in this case the
arguments and value of factorial .• and then
go~s
on with the computation.
When
an error occurs on the fifth recursion. break1 reverts to interactive mode, and
a
full break occurs.
The situaltion is then' the same as though the user had
originally performed"BREAK(FACTORIAL) instead of TRACE(FACTORIAl), and the user
can evaluate various' INTERLISP forms and direct the course of the computation.
In this case, the user examines the variable
rr,
1 as the value of this cell to factorial.
The rest of the tracing proceeds
without inCident.
and instructs break1 to return
The user would then presumably edit factorial to change l to
1•
In the second example, the user has constructed a non-recursive definition of
factorial.
He usesbreakin to insert a call to break1 just after the PROG
label lOOP. This break is to occur only on the last two iterations, i.e., when
!! is less than 2.
When the brElak occurs, the user looks at the value of !!..
mistakenly typing NN. However, the break is maintained and no damage is done.
After examining
!!.
and
m the user allows the computation to continue by typing
OK. A second break occurs after the next iteration, this time with N=O. When
this break is released, the function factorial returns its value of 120.
15.2
.. pp
FACTORIAL
(FACTORIAL
[LAMBDA (N)
(COND
«ZEROP N
L)
(T (ITIHES N (FACTORIAL (SUB1.N])
FACTORIAL
"TRACE(FACTORIAl)
(FACTORIAL)
"FACTORIAl(4)
FACTORIAL:
N = 4
FACTORIAL:
N
=3
FACTORIAL:
N
=2
FACTORIAL:
N :: 1
FACTORIAL:
N :: 0
U.B.A.
L
(FACTORIAL BROKEN)
:N
o
:RETURN 1
FACTORIAL :: 1
FACTORIAL
1
FACTORIAL = 2
FACTORIAL = 6
FACTORIAL :: 24
III
..
24
15.3
... pp
FACTORIAL
(FACTORIAL
[LAMBDA (N)
(PROG «M 1»
LOOP(COND
«lEROP N)
(RETURN H»)
(SETQ M (ITIMES H N»
(SETQ N (SUBt N»
(GO LOOP])
FACTORIAL
"'BREAKIN(FACTORIAL (AFTER LOOP) (ILESSP N 2]
SEARCHING ...
FACTORIAL
"'FACTORIAL(5)
«FACTORIAL) BROKEN)
:NN
U.B.A.
NN
(FACTORIAL BROKEN AFTER LOOP)
:N
1
:M
120
:OK
(FACTORIAL)
«FACTORIAL) BROKEN)
:N
o
:OK
(FACTORIAL)
120
...
15.2
Break1
The basic function of the break package· is break1.
Whenever INTERLISP types a
message of the form (- BROKEN) followed by':' the user is then 'talking to'
break1, and we say he is 'in a break.' break1 allows the user to interrogate
the state of the world and affect the course of the computatiori.
It uses the
prompt character ':' to indicate it is ready to accept input(s) for evaluation,
in the same way as evalqt uses ' .. '.
The user may type in an expression for
evaluation as with evalqt, and the value will be printed out, followed by
another:.
Or the user can type in one of the commands specifically recognized
by break1 described below.
15.4
Since break1 puts all of the power of INTERLISP at the user's command, he can
do anything he can do at evalqt.
For example, he can insert new breaks on
subordinate functions simply by typing:
(BREAK fnt fn2 .•• )
or he can remove old breaks and traces if too much information is being
supplied:
(UNBREAK fnJ fn4 ••• )
He can edit functions, including the one currently broken:
EDITF(fn)
For example. the user might evaluate an expression. see that the value was
incorrect, call the editor, change the function. and evaluate the expression
again, all without leaving the break.
Similarly, the user can prettyprint functions, define new· functions or redefine
old ones, load a file, compile functions, time a computation, etc . . In short,
anything that he can do at the top level can be done while inside of the break.
In addition the user can examine the pushdown list, via the functions described
in Section 1.2, and even force a return back to some higher function via the
function retfrom or reteval.
It is important to emphasize that once a break occurs, the user is in complete
control of the flow of the computation, and the computation will not proceed
wi thout specific instruction from him.
If the user types in an expression
whose evaluation causes an error, the break is maintained.
15.5
Similarly if the
user aborts a computation 2 in.ltiated from within the break,
maintained.
the break
is
Only if the user !Qives one of the coounands that exi ts from the
break, or evaluates a form which does a retfrom or reteval back out of break1,
will the computation continue. 3
Note
that break1 is just another INTERLISP function,
not a special system
feature like the interpreter or the garbage collector.
It has arguments which
are explained later, and return!) a value, the same as cons or cond or
any other function.
~
or
The value returned by break1 is called 'the value of the
break.' The user can specify th:ls 'value explicitly by using the RETURN conunand
described below.
But in most cases, the value of a
is given implicitly, via a
GO or OK conunand. and is the result of evaluating
I
the break expression,'
brkexp. which is one of the arguments to break1.
The break expression is an exprossion equivalent to the computation that
have taken place had no break occurred.
wo~ld
For example, if the user breaks on the
function FOO, the break express.1on is the body of' the definition of FOO. When
the user types OK or GO, the body of FOO is evaluated, and its value returned
as the value of the break, i.e.
to whatever function called FOO. The effect is
the same as though no break had occurred.
In other words, one can th ink of
break1 as a fancy eval, which p4!rmits interaction before and after evaluation.
The break expression then corresponds to the argument to eval.
2-----------------------------------------------------------------------------By typing control-E, see Section 16.
3
Except that break 1 does n01~ 'turn otf' control-D, i.e. a control-D will
force an immediate return back to the top level.
15.6
Break Conunands
GO
Releases the break and allows the computation to
proceed.
break t evaluates brkexp, its firs t
argument, prints the value of the break. brkexp
is set up by the function that created the call to
break1. For break or trace, brkexp is equivalent
to the body of the definition of the broken
function.
For breakin, using BEFORE or AFTER.
brkexp is NIL. For breakin AROUND, brkexp is the
indicated expression. See breakin, page 15.19.
OK
Same as GO except the value of brkexp is not
printed.
EVAL
Same as GO or OK except that the break is
maintained after the evaluation.
The user can
then interrogate the value of the break which is
bound on the variable ! value. and continue wi th
the break. Typing GO or OK following EVAL will
not cause reevaluation but another EVAL will.
EVAL is a useful command when the user is not sure
whether or not the break will produce the correct
value and wishes to be able to do something about
it if it is wrong.
RETURN form
or
RETURN fn[args]
The value of the indicated computation is returned
as the value of the break.
for example. one might use the EVAL command and
follow this with RETURN (REVERSE !VALUE).
t
Calls error! and aborts the break. i.e. makes it
"go away' without returning a value. This is a
useful way to unwind to a higher level break. All
other errors, including those encountered while
executing the GO, OK, EVAL, and RETURN commands,
maintain the break.
!EVAL
function is first unbroken, then evaluated. and
then rebroken.
Very useful for dealing with
recursive functions.
!OK
Function is first unbroken, evaluated, rebroken,
and then exited, 1.e. !OK is equivalent to !EVAL
followed by OK.
!GO
function is first unbroken, evaluated, rebroken,
and exited with value typed, i.e., 'EVAL followed
by GO.
15.7
UB
unbreaks brkfn, e.g.
(FOO BROKEN'
:un
FOOl
and FOO is now unbroken
@
resets the variable lastpos, which establishes a
context for the commands ?=, ARGS, BT, BTV, BTV*,
and EDIT, and IN? described below. lastpos is the
position of a function calIon the push-down
stack. It is initialized to the function just
before the call to breakl, i.e. stknth[-I;BREAK1]
1~reats the rest of the teletype line as its
argument( s) .
It
first
resets
las tpos
,to
stknth[-1;BREAK1] and then for each atom on the
line. , searches backward, for a call to that
atom. The following atoms are treated specially:
@
,(!)
do
not
reset
las tpos
to
stknth[-l;BREAKl] but leave ,it as it
was, and continue searching from that
point.
numbers
if negative, move lastpos back that
number of calls, if positive, forward,
i.e. reset lastpos to stknth[n;lastpos]
..
search 'forward for next atom
I
the next atom is, a number and can be
used to specify more than one call e.g.
@ FOO I 3 is equivalent to
@ FOO FOO FOO
Example:
if the push-down stack looks like
BREAK1
FOO
SETQ
COND
PROG
FIE
COND
FIE
COND
FIE
COND
PROG
FUM
(13)
(12)
(11)
(10)
(9)
(8)
(7)
(6)
(5)
(4)
(3)
(2)
(1)
then @ FIE COND will set lastpos to the position
corresponding to (7); @ @ COND will then set
lastpos to (5); @ FUM .. FIE to (4); and
@ FIE I 3 -1 to (3).
If , cannot successfully complete a search,
15.8
it
types (fn. NOT FOUND), where fn is the name of the
function for which it was searching.
When @ finishes, it types the name of the function
at lastpos, i.e. stkname[lastpos]
@ can be used on brkcoms.
In this case, the next
command on brkcoms is treated the same as the rest
of the ,teletype line.
1=
This is a multi-purpose command. Its most common
use is' to interrogate the value( 5) of the
arguments of the broken function, e.g. if FOO has
three arguments (X Y Z), then typing 1- to a break
on FOO, will produce:
'
: 1=
X=
Y =.
Z•
value of X
value of Y
value of Z
1= operates on the rest of the teletype line as
its arguments. If the line is empty. as in the
above case, it prints all of the arguments. If
the user types 1= X (CAR V), he will see the value
of X, and .the value of (CAR Y). The difference
between using 1= and typing X and (CAR Y) directly
to break1 is that 7= evaluates its inputs as of
lastpos, i.e. it uses stkeval. This provides a
way
of
examing
variables
or
performing
computations as oJ a particular point on the
.stacl. For example, @ FOO I 2 followed by 1= X
will allow the user to examine the value of X in
the previous call to FOO, etc.
1= also recognizes numbers as refering to the
correspondingly numbered argument, i •e. it uses
stkarg in this case. Thus
:@ FIE
FIE
:1= Z
will print the name and value of
argument of FIE.
the
second
7= can also be used on brkcoms, in which case the
next command on brkcoms is treated as the rest of
the teletype line. For example, if brkcoms 1s
(EVAL 1= (X Y) GO), brkexp will be evaluated, the
values of X and Y printed, and then the function
exited with its value being printed.
BT
Prints a backtrace of Junctton names only starting
at lastpos.
(See discussion of @ above) The
several nested calls in system packages such as
break, edit,and the top level executive appear as
the single entries ·-BREAK··, •• EDITOR •• , and
·-TOP*. respectively.
15.9
BTV
Prints a back trace of function
variables beginning at lastpos.
names
BTV*
Same as BTV except also prints arguments
internal calls to eva!. (See Section 12)
BTV!
Same as BTV except prints el1eruthtng on stack.
(See Section 12).
wt th
of
BT, BTV, BTV*, and BTV! all permit an optional functional argument which is a
predicate that chooses functions to be skipped on the backtrace, e.g., BT SUBRP
will skip all SUBRs. BTV (lAMB04A (X) (NOT (MEMS X FOOFNS») will skip all but
those functions on FOOFNS.
If used as a brkcom the functional argument is no
longer optional, i.e. the next brkcom must either be the functional argument,
or NIL if no functional argument is to be applied.
For BT, BTV, BTV*, and BTV!, if control-P is used to change a printlevel during
the
backtrace.
the
printlevel
will
be
restored
after
the
backtrace
is
completed.
ARGS
Prints the names of the variables bound at
lastpos, i.e. variables[lastpos] (Section 12).
For most cases. these are the arguments to the
func:tion
entered
at
that
posi tion.
i. e.
arglist[stkname[lastpos]].
The following two conunands are for use only with unbound atoms or undefined
function breaks (see Section 16).
= form,
= fn[args]
for the break follo,ing an unbound atom
error. Sets the atom to the value of the form, or
function and arguments, exits from the break
returning
that
value,
and
continues
the
computation, e.g.
only
U.B.A.
(FOO BROKEN)
:= (COpy FIE)
sets; FOO and goes on.
15.10
-> expr
for use either with unbound atom error, or
undefined function error. Rep\rces the expression
containing the error with expr (not the value of
expr) e.g ••
U.D.F.
(FOOl BROKEN)
:-> FOO
changes the
computation.
FOOl
to
FOO
and
continues
the
expr need not be atomic, e.g.
U.B.A.
(FOO BROKEN)·
:-> (QUOTE Foo)
For U.D.F. breaks. the user can specify a function
initial arguments, e.g.
and
U.D.F.
(MEHBERX BROKEN)
:-> MEMBER X
Note that in the case of a U.D.F. error occurring
immediately following a call to ~, e.g.
(APPLY X Y) where the value of x is FOO and FOO is
undefined, or a U.B.A. error immediately following
a call to eval, e.g. (EVAL X), where the value of
x is FOO--and FOO is unbound, there is no
expression containing the offending atom. In-this
case, - > cannot operate, so ? is printed and no
action taken.
EDIT
designed for use in conjunction with breaks caused
by errors.
Facilitates editing the expression
causing the break:
NON-NUMERIC ARG
NIL
(IPLUS BROKEN)
:EOIT
IN Foo .••
(IPLUS X Z)
EDIT
~(3
Y)
*OK
FOO
and user can continue by typing OK, EVAl, etc.
4--~·--~-----~---~--~·~~-------------------~---------------------------------~-
- > does not change just brkexp; it changes the function or expression
containing the erroneous form. In other words, the user does not have to
perform any additional editing.
15.11
This command is very simple conct!ptually, but complicated in its implementation
by all of the exceptional cases involving inteactions with compiled functions,
breaks
on
Therefore,
user
we
functions,
error
breaks,
breaks
within
breaks,
et
a1.
shall give the following simplified explanation which will
account for 90% of the situations arising in actual usage.
For those others,
EDIT will print an appropriate failure message and return to the break.
EDIT begins by searching up the stack beginning at lastpos (set by @ command,
initially position of the break) looking for a form, i.e. an internal call to
eval.
Then EDIT continues from that pOint looking for a call 'to an interpreted
function, or to eval.
It then calls the editor on either the EXPR or the
argument to eval in such a way as. to look for an expression !!l to the form that
it first found.
begin.
It then prints the form, and permits interactive editing to
Note that the user can then type successive O's to the editor to see
the chain of superforms for this computation.
If the user exits from the edit with an OK, the break expression is reset, if
possible, so that the user can continue with the computation by simply typing
OK. 6 However, in some situation~, the break expression cannot be reset. For
example, if a compiled function FOO incorrectly called putd and caused the
error ARG NOT ATOM followed by a break on putd, EDIT might be able to find the
form headed' by FOO,
function.
and also find that form in some higher interpreted
But after the user cor'rected the problem in the FOO-form, if any, he
would still not have in any way informed EDIT what to do about the immediate
problem, i.e. the incorrect call to putd.
EDIT would find the putd form
j~tself,
However, if FOO were tnterpreted
so that when the user corrected that
form, EDIT could use the new corrected form to reset the break expression . . The
two cases are shown below:
6-----------------------------------------------------------------------------Evaluating the new brkexp will involve reevaluating the form that causes
the break, e.g. if (PUTD (QUOTE (FOO» big-computation) were handled
EDIT, big-computation would be reevaluated.
15.12
by
ARG NOT ATOM
(FUM)
(PUTD BROKEN)
:EOIT
IN FIE ...
(FOO X)
EDIT
"(2 (CAR X»
"OK
NOTE: BRKEXP NOT CHANGED
FIE
:?=
U = (FUM)
:(SETQ U (CAR U»
FUM
:OK
PUTO
IN?
ARG NOT ATOM
(PUlO BROKEN)
:EOIT
IN FOO .••
(PUTD X)
EDIT
*(Z (CAR X»
*OK
FOO
:OK
PUTO
similar to EDIT, but just prints parent form, and
superform, but does not call editor, e.g.
ATTEMPT TO RPLAC NIL
T
(RPLACO BROKEN)
:IN?
FOO: (RPLACD X Z)
Although EDIT and IN? were designed for error breaks, they can also be useful·
for user breaks.
For example, if upon reaching a break on his function FOO,
the user determines that there is a problem in the call to FOO, he can edit the
ca~ling
form and reset the break expression with one operation by using EDIT.
The following two protocol's with and without the use of EDIT, illustrate this:
15.13
(FOO BROKEN)
:1=
(FOO BROKEN)
:1=
X = (A B C)
X
= (A
Y
Y
=
==
0
:EOIT
IN FIE ...
(FOO V U)
EDIT
*(SW 2 3)
*OK
8
FIE
:OK
FOO
:8T
FOO
SETQ
COND
PROG
FIE
find which function
FOO is called! from
(aborted with tE)
:EOITF(FIE)
EDIT
-F FOO P
(FOO V U)
-(SW 2 3)
*OK
FIE
:(SETQ Y X)
B C)
0
edit it
reset X and Y
(A'B C)
: (SETQQ X 0)
o
:1=
X
=
0
Y = (A B C)
:OK
FOO
check them
!Jrkcoms
The fourth argument to break1 is brkcoms. a list of break commands that break1
interprets and executes as though they were teletype input.
One can think of
brkcorns as another input file which always has priority over the teletype.
Whenever
brkcoms=NIL,
break!
Ireads
its
next
command
from
the
teletype.
Whenever brkcoms is not NIL, break1 takes as its next convnand car[brkcorns] and
sets brkcoms to cdr[brkcoms].
value of the variable x
after
For example, suppose the user wished to see the
,8
function was evaluated.
He would set up a
break wi th brkcoms= (EVAL (PRINT X) OK), which would have the desired effect.
The function trace uses brkcoms: it sets up a break with two commands; the
first one prints the arguments oj: the function, or whatever the user specifies,
6-------------------------------··---------------------------------------------and
have not been changed, but brkexp has. See previous footnote.
~
~
15.14
and the second is the command GO, which causes the function to be evaluated and
its value printed.
If brkcoms is not NIL, the value of
8
break command is not printed.
If you
desire to see a value, you must print it yourself, as in the above example with
the command (PRINT X).
Motel whenever an error occurs. brkcoms is set to
break. occurs.
NIL, and a lulL interactive
Brkfile
The break package has a facility for redirecting ouput to a file.
The variable
brkfile should be set to the name of the file, and the file must be opened.
All output resulting from brkcoms will be output to brkfile, e.g. output due to
TRACE.
Output due to user typein is not affected. and will always go to the
terminal.
brkfile is initially T.
Breakmacros
Whenever an atomic command is given break1 that it does not recognize, either
via brkcoms or the teletype, it searches the list breakmacros for the command.
( .•. (macro command 1 command Z ••• command n ) •.• ).
If the command is defined as a macro, break1 simply appends its definition,
The form
of breakmacros is
which is a sequence of commands, to the front of brkcoms, and goes on.
command is not contained in breakmacros.
If the
it is treated as a function or
variable as before.
Example:
the command· ARGS could be defined by including on breakmacros:
(ARGS (PRINT (VARIABLES lASTPOS T»).
15.15
15.3
Break Functions
break1[brkexp;brkwhen;brkfn;brkcoms;brktype]
is an nlambda.
brkwhen determines whether a break
is to occur.
If its value is NIL,
brkexp is
evaluated and returned as the value of break1.
Otherwise
a
break
occurs
and
mes,sage is printod using brkfn.
taken
from
interpreted.
brkcoms
or
an
identifying
Commands are then
the
teletype
GO,
!GO,
The commands,
and
OK,
!OK,
RETURN and t, are the only ways to leave breakl.
The command EVAL causes brkexp to be evaluated,
and saves the value on the variable 'value.
commands
can
be
defined
for
is NIL
for
Other
break1
user
via
breakmacros.
brktype
breaks.
INTERRUPT for
control-H breaks,
and ERRORX for
the input buffer is cleared and saved.
(For control-H
err'or breaks.
For error breaks.
breaks, the input buffer was cleared at the time the control-H was typed, see
Section 16.) In both cases, if the break returns a value, i.e., is not aborted
via t or control-D, the input buffer will be restored (see Section 14).
breakO[fn;when;coms]
set~i
up a break on the function fn by redefining
fn as a call to break1 with brkexp an equivalent
deflni tion of fn,
and when.
brkfn. brkcoms.
brk~,hen.
fn,
and corns,
as
Puts property BROKEN on
property list of fn wi th value a gensym defined
with
the
original
definition.
Puts
property
BRKINFO on property list of fn with value (BREAKO
when coms) (For use in conjunction with rebreak).
15.16
Adds fn to the front of the list brokenfns.
Value
is fn.
If fn is non-atomic and of the form (fnl IN fn2),
breakO first calls a function which changes the
name of fnt wherever it appears inside of fn2 to
that of a new function,
initially defines as fnt.
rnt-IN-fn2,
which
it
Then breakO proceeds to
break on fnl-IN-fn2 exactly as described above.
This
procedure
is
useful
for
breaking
on
function that is called from many places,
a
but
where one is only interested in the call from a
specific
function,
(PRINT IN FIE), etc.
e.g.
(RPlACA IN FOO),
It is similar to breakin
described below, but can be performed euen when
FN2 is compiled or blockcompiled, whereas breakin
only works on interpreted functions.
If fnt is not found in fn2, breakO returns the
value (fnl NOT FOUND IN fn2).
If fn t is found in fn2, in addition to breaking
fnt-IN-fn2
and adding
fnt-IN-fn2
to
the
list
brokenfns, breakO adds fnt ,to the property value
for the property NAMESCHANGED on the property list
of
~
and adds the property ALIAS with the value
(fn2. fnl) to the property list of rnt-IN-fn2.
This will enable unbreak to recognize what changes
have been made and restore the function fn2 to its
original state.
15.17
If fn is nonatomic and not of the above form,
bre,akO is called for each member of fn using the
sam!9 values for when,
~,
and file specified in
this call to breakO.
This distributivity permits
the user to specify complicated break conditions
on several functions without excessive retyping,
e. g. ,
breakO[(FOOt «PRINT PRINt) IN (F002 FOOl»);
(NEQ X T);(EVAL 1= (Y Z) OK)]
will break on FOOt, PRINT-IN-FOO2, PRINT-IN-F003,
PRINt-IN-F002 and PRINt-IN-FOO3.
If In is non-atomic, the value of breakO is a list
of the individual values.
break[x]
is a nospread nlambda.
for each atomic argument,
it performs breakO[atom;T].
performs
apply[BREAKO;list].
for each list,
For
it
example,
breilk[FOOl (FOO2 (GREATERP N 5) (EVAL»]
equ:lvalent
to
breakO[FOO1,T]
is
and
breiikO[ FOOl; (GREATERP N 5); (EVAL)]
trace[x]
is a nospread nlambda.
For each atomic argument,
it performs breakO[atom;T;(TRACE 1= NIL GO)]? For
each list argument, £!.!: is the function to be
traced, and cdr the forms the user wishes to see,
i.e.
trace performs:
breakO[car[list];T;list[TRACE;1=; cdr[list],GO]]
7-------------------------------··---------------------------------------------The flag TRACE is checked for in breakt and causes the message 'function :'
to be printed instead of (function BROKEN).
15.18
for example, TRACE(FOOI (FOOl Y»
FOOl and FOOl to be traced.
will cause both
All the arguments of
FOOl will be printed. only the value of Y will be
printed for FOO2.
In the special case that the
user wants to see onlu the value, he can perform
TRACE«fn».
This sets up a break with commands
(TRACE 1- (NIL) GO).
Note: the user can always call breakO himself to oetain combination of options
of break1 not directly available with break and trice.
These two functions
merely provide convenient ways of calling breakO, and will serve for most uses.
Breakin
Breakin enables the user to insert a break. i.e. a call to break1,
specified location in an interpreted function.
at a
For example, if !.2.!! calls fie,
inserting a break in !22 before the call to fie is similar to breaking fie.
However. break in can be used to insert breaks before or after prog labels,
particular SETQ expressions, or even the evaluation of a variable.
This is
because breakin operates by calling the editor and actually inserting a call to
break1 at a specified point inside of the function.
The user specifies where the break is to be inserted by a sequence of editor
commands.
These commands are preceded by BEFORE, AFTER, or AROUND, which
break in uses to determine what to do once the editor has found the specified
point, i.e. put the call to break! BEFORE that point, AFTER that point, or
AROUND that point.
For example, (BEFORE COHD) will insert a break before the
first occurrence of cond,
(AFTER COHO Z 1) will insert a break after the
predicate in the first
clause, (AFTER BF (SETQ X &»
X is set.
~
after the la&t place
Note that (BEfORE TTY:) or (AFTER TTY:) permit "the user to type in
cOlMlands to the editor. locate the correct pOint, and verify it for himself
15.19
breakin[fn;where;when;coms] breakin is an nlambda.
to when and
~
when and £Qm! are similar
for breakO, except that if when
is NIL, T is used.
where specifies where in the
definition of 'fn the call to breakl is to be
inserted.
(8ee earlier discussion).
If fn is a compiled function,
break in returns
(fn UNBREAKABLE) as its value.
If fn is int'erpreted, breakin types SEARCHING ..•
while
it
calls
the
editor.
If
specified by where is not found,
(NOT FOUND)
and exits.
the
location
break in types
If it is found, breakin
adds the property BROKEN-IN with, value T, and the
property BRKINFO with value (where when coms) to
the property list of fn. and adds fn to the front
of the list brokenfns.
Multiple break points, can be inserted with a
single call to breakin by using a list of the form
( (BEFORE ••• )
(AROUND ••• ) )
for where.
It
is
also possible to call break or trace on a function
which has been modified by breakin, and conversely
to break in a function which has been redefined by
a call ,to break or trace.
unbreak[x]
unbreak
1s
a
nospread
nlambda.
It
takes
an
indefinite number of functions modified by break,
trace,
or breakin and restores
original state by calling unbreakO.
of values of unbreakO.
15.21
them to
their'
Value is list
unbreak[] will unbreak all functions on brokenfns,
in reverse order.
It first sets brkinfolst to
NIL"
unbr'eak[ T] unbreaks just the first
bro~~en
fns,
i. e.,
the
most
function on
recently
broken
fun(:tion.
unbreakO[fn]
fn to its original state.
res1~ores
If fn was not
broken, value is (NOT BROKEN) and no changes are
mado.
If fn was modified by breakin, unbreakin is
called to edit it back to its original state.
If
fn 'tas created from (fnl IN fn2), i.e. if it has a
property ALIAS, the function in which fn appears
is restored to its original state.
All
functions
break
that were created
eliminated.
by
the
dununy
are
Adds property value of BRKINFO to
(front of) brkinfolst.
Note: unbreakO[(fnl IN fn2)] is allowed: unbreakO
will operate on fnl-IN-fn2 instead.
unbreakin[fn]
performs the
appropriate
editing operations
to
eliminate all changes made by break in .
fn may be
either
function.
the
name or
Value 15 fn.
unbl~eak
definition
of
a
Unbreakin is automatically called by
if fn has property BROKEN-IN with value T
on its property list.
rebreak[x]
is an nlambda, nospread function for rebreaking
functions
that
15.22
were
previously
broken
without
having to respecify the break information.
For
each function on !, rebreak searches brkinfolst
for
break(s)
operation.
and
performs
Value
is
the
a
corresponding
list
of
values
corresponding to calls to breakO or breakin.
If
no information is found for a' particular function,
value is (fn - NO BREAK INFORMATION SAVED).
rebreak[] rebreaks everything on brkinfolst, i.e.,
rebreak[] is the inverse of unbreak[].
rebreak[T]
rebreaks
brkinfolst,
i.e.,
just
the
the
first
function
break
most
on
recently
unbroken.
changename[fn;from;to]
changes all occurrences of from to
may be compiled or blockcompiled.
~
in fn.
fn
Value is fn if
from was found, otherwise NIL. Does not perform
any modifications of property lists.
Note that
from and to do not have to be functions, e.g. they
can be names of variables, or any other literals.
virginfn[fn;flg]
is
the
function
that
knows
how
to
restore
functions to their original state regardless of
any
amount
of
breaks,
breakins,
,advising,
compiling and saving exprs, etc.
It is used by
prettyprint,
compiler.
f.!a=NIL,
as.
define,
and
the
If
for prettyprint, it does not modify
the definition of fn in the process of producing
8
·clean· version of the definition, i.e. it works
on a copy.
15.23
If f1s.=T as for the compiler and
define, it physically restores the function to its
original state.
malting t
e. g.
and prints
the
changes
it
fOO UNBROKEN, FOO UNADVISED,
NAMES RESTORED, etc.
is
FOO
Value is the virgin function
definition.
baktrace[posl;pos2:skipfn:varsflg:-form-flg:a11f1g]
~~
to
pos2.
If
sktpfn[ stkname[ pos]]
prints
skipfn
is
back trace
is
T.
(including all variables).
var-sflg=T for back trace a la BTV
var'sflg=T, -form-flg=T - BTV~sf1g=T.
a11flg=T - BTV!
15.24
pos
not
from
NIL,
is
and
skipped
Index for Section 15
Page
Numbers
AFTER (as argument to break1n) ••.••••••••.•••.••
ALIAS (property name) ..•.••.••••.•••.••••••.••.••
ARGLIST[X]
.........•
e •••••••••••••••••••••••••••
ARGS (break command) .•.....••••••••••••••••••••.
AROUND (as argument to break1n) ••.••••••••.••.••
back trace
II
••••••••••••••••••••••••••••••••••••••
BAKTRACE[FROM;TO;SKIPFN;VARSFLG~·FORM·FlG;ALLFLG].
BEFORE (as argument to breakin) ..•.•.••••••••.•••
BREAK[ X] NL*
.
lit
••••••••••••••••••••••••••••••••••
break conunands ........•..•••••..••••.••.••••••••
break expression •..... ~ .•••..••.•••• ~ •••••••••••
BREAK INSERTED AFTER ~typed by break1n) ••••.••••
break package ............•..••••••••••••••••••••
BREAKO[FN;WHEN;COMS;BRKFN;TAIL] ...•.•••.••••.•.•
BREAKl[BRKEXP;BRKWHEN;BRKFN;BRKCOHS;BRKTVPE] NL
BREAKIN[FN;WHERE;WHEN;BRKCOMS] NL ••.••••..••.•••
BREAKMACROS (break variable/par~eter) ••••••••••
....... ~ .....
breakpoint
It
••••••••••••••••••••••••
BRKCOMS (break variable/parameter) •••••••••.••••
BRKEXP (break variable/parameter) •••••••••••••.•
BRKFILE (break variable/parameter) ••••••••••.•••
BRKFN (break variable/parameter) ••••.••••••••••••
BRK INFO (property name) ......•:..••.•••••••••.••.
BRKINFOLST (break variable/parameter) •••••••.•••
BRKTVPE (break variable/parameter) •••••••••••••.
BRKWHEN (break variable/parameter) ••••••••••••••
BROKEN (typed by system) ..•.•••.••••••••••••••••
BROKEN-IN (property name) •.•••••.•••••••••••••••
BROKENFNS (break variable/parameter) ••••.•••••••
BT (break command)
...•••••••••••••••••••••••••••
BTV (break command) ..••••••••••••••••.••••••••••
BTV! (break command) •••••.••••••••••••••••••••.•
BTV· (break command) •..•..•.•••••.•••.••••••••••
CHANGENAME[FN;FROH;TO] .••••••.••••.•••••••••..••
control-D
control-E
control-H
control-P
debugging
...................................... .
s
••••••••••••••••••••••••••••••••••••••
...
............
.................•................
0
••••••••••••••••
00
1'
••••••••••••••••••
••••••••••••••••••••••••••
e ••••
EDIT (break con:unand)
..•.•••....••••••••••.••••.•
editing compiled functions ••••.•.••••••••••••.••
ERROR! [] SUBR
••••••••••••••••••••• ,. •••••••••••••
EVAL (break command) ............................ .
EVALQT[ CHAR] ..........•...•....••••.••••••••••••
(fn - NO BREAK INFORMATION SAVED) •••.••••••..•••
( fn 1 IN fn2)
..
0
•• "
••••••••••••••••••••••••••••••
( fn 1 NOT FOUND IN fn2)
fnl-IN-fn2
•••.••••
..................
GENSYM[CHAR]'
III
0
•••••••••
eo • • • • • •
•••••••••••••••••••
•••..•••••••••••••••••••••••••••••••
GO (break command) ...•..•.•.••••••••••••••••••••
IN? (break conunand) .....•...••••••••••••••••••••
input buffer
............................
0
•••••••
LASTPOS (break variable/parameter) ••••••••••••••
NAMES RESTORED (typed by system) •••••.••••••••••
NAMESCHANGEO (property name) ..••••••••••••.•••••
NOBREAKS (break variable/parameter) •••••••••••••
INDEJ('15.1
15.7,19-20
15.17,22
15.10
15.8,10
15.7,19-20
15.9-10,24
15.24
15.7,19-20
15.1,7,18-19,21
15.7-14
15.6,12
15.20
15.1-24
15.16-19,21,23
15.1-2,4,16,18-19,21
15.2,7,17,19,21-23
15.15,,16
15.2
15.9,14-16
15.6-7,9,11-12,14,16
15.15
15.8,16
15.16,21-22
15.22-23
15.16
15.16
15.4,16
15.21-22
15.17,21-22
15.8~9
15.8,10
15.10
15.8,10
15.23
15.6,16
15.6,20
15.16
15.10
15.1
15.8,11-13
15.23
15.7
15.7,14,16.20
15.5
15.23
15.17,22
15.17
15.17,22
15.16
15.6-7,15-16
15.8,13
15.16
15.8-10,12
15.24
15.17
15.20
Page
Numbers
( NO T BROK EN)
•••••.••••••••••••••••••••••••••••••
(NOT FOUND) (typed by break)
••••••••••••••••••••
(NOT FOUND) (typed by break1n)
••••••••••••••••••
NOTE: BRKfXP NOT CHANGED. I( typed by break)
••••••
OK (break command)
••••••••••••••••••••••••••••••
prompt character
••••••••••••••••••••••••••••••••
REBREAK[ X] NL*
••••••••••.•••••••••••••••••••••••
RETEVAl[POS;FORM] SUBR ••.•••••••••••••••••••••••
RETFROM[POS;VAlUE] SUBR •••••••••••••••••••••••••
RE TURN (break command)
.......................... .
SEARCHING .•• (typed by break1n)
•••••••••••••••••
STKARG[N;POS] SUBR ••••••••••••••••••••••••••••••
STKEVAl[POS;FORM] SUBR ••••••••••••••••••••••••••
STOP (edit conunand)
•••••••••••••••••••••••••••••
TRACE[ X] NL*
...••.....•...••••••••••.•••.•.•••••
Try: (edit cornrnand)
•••••••••••••••••••••••••••••
U.B.A. breaks
................................... .
U.O.F. breaks
........•..•••..•••••••.•••••.•.•••
UB (break command)
••••••••••••••••••••••••••••••
UNADVISED (typed by system)
•••••••••••••••••••••
UNBREAK[X] NL*
••••••••••••••••••••••••••••••••••
UNBREAKO[ FN; TAIL] •••••••••••••••••••••••••••••••
(UNBREAKABLE)
•••••••••••••••••••••••••••••••••••
UNBREAK IN[ FN]
•••••••••••••••••••••••••••••••••••
UNBROKEN (typed by system)
••••••••••••••••••••••
value of a break
••••••••••••••••••••••••••••••••
VARIABlES[POS]
••••••••••••••••••••••••••••••••••
VIRGINfN[FN;FlG] .•••••••••••••••••••••••••••••••
'EVAL (break command)
•••••••••••••••••••••••••••
! GO (break command) •••••••••••••••••••••••••••••
! OK (break corrunand) •••••••••••••••••••••••••••••
!VAlUE (break variable/parameter)
•••••••••••••••
*·BREAK*· (in backtrace)
••••••••••••••••••••••••
--EDITOR·· (in backtrace)
•••••••••••••••••••••••
--TOp·· (in backtrace)
••••••••••••••••••••••••••
-) (break command)
••••••••••••••••••••••••••••••
: (typed by sys tern)
•••••••••••••••••••••••••••••
= (break command)
•••••••• '.••••••••••••••••••••••
1= (break command)
•••••••., ••••••••••••••••••••••
@ (break command)
............................... .
t (break conunand)
••••••••..••••••••••••••••••••••
~ (typed by system)
•••••••••••••••••••••••••••••
INDEX.15.2
15.22
15.9
15.20-21
15.12
15.6-7,12,14,16
15.4
15.16,22-23
15.5
15.5
15.6-7,16
15.21
15.9
15.9
15.20
15.1,7,14,18-19,21
15.19-20
15.10
15.11
15.8
15.24
15.17,21-22
15.22
15.21
15.22
15.24
15.6
15.10
15.23
15.7
15.7,16
15.7,16
15.7,16
15.9
15.9
15.9
15.11
15.4
15.10
15.8-9
15.8-9,12
15.7,16
15.4
SECTION 16
ERROR HANDLING
16.1
Unbound Atoms and
Underi~ed
Functions
Whenever the interpreter encounters an atomic form with no binding on the pushdown list, and whose value contains the atom NOBIND. 1 the interpreter calls
the
function
faul teval.
Similarly,
fauI"teval
is called when
a
list
is
encountered, £!r of which is not the name of a function or a function object. 2
The value returned by faulteval is used by the interpreter exactly as though it
were the value of the form.
faulteval is defined to print either U.S.A., for
yn~ound
!tom, or U.D.F., for
yn!!efined function, and then to call break1 giving it the offending form as
brkexp.8 Once inside the break, the user can set the atom, define the function,
return a specified value for the form using the RETURN command, etc., or abort
i---~---------------·--~--~---------------------------------~------------------
All atoms are initialized (when they are created by the read program) with
their value cells (car of the atom) NOSIND, their function cells NIL, and
their property lists (cdr of the atom) NIL.
2
See Appendix 2 for complete description of INTERLISP interpreter.
8
If DWIM is enabled (and a break is going to occur), faulteval also prints
the offending form (in the case of a U.S .A., the parent form) and the name
of the function which contains the form. For example,' if FOO contains
(CONS X FIE) and FIE is unbound, faulteval prints:
U.B.A. FIE [in FOO] in (CONS X FIE). Note that if DWI" is not enabled, the
user can obtain this information after he is inside the break'via the IN?
command.
16.1
the break using the
t
command.,
If the break is exited with a value,
the
computation will proceed exactly as though no error had occurred. 4
The decision over whether or nlot to indu.ce a break depends on the depth of
computation. and the amount of time invested in the computation.
algorithm is described in detail below
it
to
say that
i~
The actual
the section on breakcheck.
Suffice
the parameters affecting this decision have been adjusted
empirically so that trivial type-in errors do not cause breaks, but deep errors
do.
16.2
Teletype Initiated Breaks
Control-H
Section 15 on the break package described how the user could cause a break when
a specified function was entered.
The user can also indicate his desire to go
into a break at any time while a program is running by typing control-H. 6 At
the next point a function is about to be entered, the function interrupt is
called instead.
interrupt types INTERRUPTED BEFORE followed by the function
4-----------------------------------------------------------------------------A similar procedure is follo'wed whenever ~ or apply· are called with an
undefined function. i.e. OnE! whose ~ is NIL. In this case, faul tapply
1s called giving it the function as its first argument and the list of
arguments to the function as its second argument. The value returned by
faul taJ~I!_~ is used as the value of ~ or !Q~. faultapply is defined
to
print
U.D.F.
and
then
call
break1
giving
it
(APPLY (QUOTE fn) QUOTE args» as brkexp. Once inside the break, the user
can define the function, return a specified value, etc. If the break is
exi ted wi th a value, the computation will proceed exactly as though no
error had occurred. faultapi2!I is also called for undefined function calls
from compiled code.
6
As soon as control-H is typed, INTERLISP clears and saves the input buffer,
and then rings the bell, indicating that it is now safe to type ahead to
the upcoming break. If the break returns a value, i.e., is not aborted via
t or control-D, the contents of the input buffer before the control-H was
typed will be restored.
16.2
name, constructs an appropriate break expression, and then calls break1.
user can then
examin~
The
the state of the computation, and continue by typing OK,
GO or EVAl, and/or retfrom back to some previous point, exactly as with a user
break.
Control-H breaks are thus always 'safe'.
Note that control-H breaks
are not affected by the depth or time of the computation.
However, they onlu
occur when a function is called, since it is only at this time that the system
is in a ·clean· enough state to allow the user to interact.
Thus,
if a
compiled program is looping without calling any functions, or is in a 1/0 wait,
control-H will not affect it.
Control-B, however, will.
Control-B
Control-B is a stronger interruption than control-H.
It effectively generates
an inunediate error.
This error is treated like any other error except that it
always causes a break, regardless of the depth or time of the computation. 6
Thus if the function FOO is looping internally, typing control-B will cause the
computation to be stopped, the stack unwound to the point at which FOO was
called, and then cause a break.
Note that the internal variables of FOO are
not available in this break, and Similarly, FOO may have already produced some
changes in the environment before the control-B was typed.
Therefore whenever
pOSSible, it is better to use control-H instead of control-B.
Control-E
If the user wishes to abort a computation, without causing a break, he should
type control-E.
Control-E does not go through the normal error machinery of
scanning the stack, calling breakcheck, printing a message, etc. as described
below, but simply types a carriage-return and unwinds.
a-----------------------------------------------------------------------------However, setting helpflag to N~L will suppress the break. See discussion
of breakcheck below.
16.3
16.3
Other Types of Errors
In addition to U.B.A. and U.O.F. errors, there are currently 28 other error
typei
etc.
1n
INTERLISP,
e.g.
P-STACK OVERFLOW, NON-NUMERIC ARG, FILE NOT OPEN,
A complete list 1s given later in this section.
When an error occurs,
the decision about whether or not to break is handled by breakcheck and is the
same as with U.B.A. and U.O.F. errors.
If a break is to occur, the exact
action that follows depends on the type of error.
to
occur
following
evaluation
ATTEMPT TO RPlAC NIL error),
of
For example, if a break is
(RPlACA NIL (ADDI 5»
the message
printed will be
(which
causes
an
(RPlACA BROKEN),
brkexp will be (RPlACA U V W), U will be bound to NIL, V to 6, and W to NIL,
and the stack will look like the user had broken on rplaca himself.
Following
a NON-NUMERIC ARG error. the sy:stem will type IN followed by the name of the
most
recently entered function,
and then (BROKEN).
effectively be in a break inside of this function.
The system will
then
brkexp will be a call to
ERROR so that if the user types OK or EVAl or GO, a ? will be printed and the
break maintained.
However, if the break is exited with a value via the RETURN
command,7 the computation will p."oceed exactly as though no error had occurred.
16.4
Breakcheck - When to Break
The decision as to whether or not to induce a break when an error occurs is
handled by the function breakcheck. 8 The user can suppress all error breaks by
setting the variable helpflag to NIL (initially set to T).
decision
is
affected by
two
factors:
the
length
If helpflag=T, the
of time
spent
in
the
7--------------------------------·----------------------------------.----------Presumably the value will be a number, or the error will occur again.
8
Breakcheck is not actually available to the user for adVising or breaking
since the error package is block-compiled.
16.4
computation, and the depth of the computation at the time of the error. 9 If the
time
is
greater
than helptime or the depth is greater
than helpdepth,
breakcheck returns T, meaning a break will occur.
Since a function is not actually entered until its arguments are evaluated,10
the depth of a computation is defined to be the sum of the number of function
calls plus the number of internal calls to eval.
expression
Thus if the user types in the
[MAPC FOO (FUNCTION (LAMBDA (X) (COND «NOT (MEMBX FIE»
for evaluation, and FIE is not
bound~
(PRINT Xl
at the point of the U.B.A. FIE error, two
functions, mapc and cond, have been entered, and there are three internal calls
to
corresponding
(CONO «NOT (MEMB X FIE»
to
the
evaluation
of
the
forms
(PRINT X»), (NOT (MEMB X FIE»,· and (MEMB X FIE).ll
The depth is thus 5.
breakcheck begins by searching back up the parameter stack looking for an
errorset. 12 At the same time, it counts the number of internal calls to eval,
as indicated by pseudo-variable bindings called eval-blips.
See Section 12.
As soon as (if) the number of eval-blips exceeds helpdepth, breakcheck can stop
searching for errorset and return T, since the position of the errorset is only
needed when a break is not going to occur. ' Otherwise, breakcheck continues
9--~-----------------~-------------------------------- -------------------------
Except that control-B errors always break.
10
Unless of course the function does not have its arguments evaluated, i.e.
is an FEXPR, FEXPR*, CFEXPR, CFEXPR*, FSUBR or FSUBR*.
11
for complete discussion of the stack and the interpreter, see Section 12.
12
errorsets are simply markers on the stack indicating how far back unwinding
is to take place when an error occurs, i.e. they segment the stack into
sections such as that if an error occurs in any section, control returns to
the point at which the last errorset was entered, from which NIL is
returned as the 'value of the errorset. See page 16.14.
16.5
search ing un til either an errorset is found 13 or the top of the stack is
reached.
Breakcheck then
complet~s
the depth check by counting the number of
function calls between the error and the last errorset, Qr the top of the
stack.
If the number of calls I)lus the number of eval-blips (already counted)
is greater than or equal to helpdepth, initially set to 9,14 breakcheck returns
T. Otherwise, it records the position of the last
errors~t,
and the value of
errorset • s second argument, which is used in deciding whether to print the
error messaga, and returns NIL.
breakcheck next measures the length of time spent in the computation by
subtracting the value of the variable helpclock from the value of (CLOCK 2).16
If the difference is greater than helptime milliseconds, initially set to 1000,'
then
a break wi 11 occur,
i. e. , breakcheck returns T,
otherwise NIL.
variable helpclock is rebound to the current value of (CLOCK Z)
The
for each
computation typed in to lispx or to a break.
The time cri terion for breaking can be suppressed by .setting helptime to NIL
(or a very big number), or by binding helpclock to NIL. Note thats'etting
helpclock to NIL will not have any effect because helpclock is rebound by lispx
and by break.
If breakcheck is NIL, i.e., a break is not going to occur, then if an errorset
was found, NIL is returned (via retfrom) as the value of the errorset, after
first printing the error message if the errorset's second argument was
TRUE~
ij--------------------------------------------------------~--------------------
If the second argument to the errorset is INTERNAL, the errorset is ignored
and searching continues. See discussion of errorset, page 16.14.
14
Arrived at empirically, tak9s into account the overhead due to lispx or
break.
16
Whose value is number of milliseconds of compute t'ime.
16.6
See Section 21.
If there was no errorset, the message is printed, and control returns to
evalgt.
This procedure is followed for all types of errors.
Note that for all error breaks for which a break occurs, break1 will clear and
save the input buffer.
t
If the break returns a value, i.e., is not aborted via
or control-D, the input buffer will be restored as described in Section 15.
16.5
Error Types
There are currently
twenty-ei~ht
listed below by error number.
error types in the INTERLISP system.
They are
The error is set internally by the code that
detects the error before it calls the error handling functions.
It is also the
value returned by errorn if called subsequent to that type of error, and is
used by errormess for printing the error message.
Most error types will print the offending expression following the message,
e . g., NON-NUMERIC ARG NIL is very common.
Error type 18 (control-B) always
causes a break
All other errors cause breaks if
(unles~
helpflag ,is NIL).
breakcheck returns T.
o
NONXMEM
reference
to
~-e!istent
~ory.
Usually
indicates system is very sick.
Currently not used.
1
2
P-STACK OVERFLOW
. occurs when computation is too deep, either with
respect to number of function calls, or number of
variable bindings.
Usually because of a non-
tenm1nating recursive computation, i.e. a bug.
16.7
3
ILLEGAL RETURN
call to return when not inside of an interpreted
pr(]i1.
4
ILLEGAL ARG - PUTD
second argument to putd (the definition) is not
NIL, a list, or a pointer to compiled code.
5
ARG NOT ATOM - SET
first argument to set, setg, or !!1gg (name of the
variable) is not a literal atom.
6
ATTEMPT TO SET NIL
via set or setq
7
ATTEMPT TO RPlAC NIL
attempt either to rplaca or to rplacd NIL with
something other than NIL.
8
UNDEFINED OR ILLEGAL GO
DQ
'when not inside of a
~,
or 9Q to nonexistent
label.
9
FILE WON'T OPEN
From infile or outfile, Section 14.
10
NON-NUMERIC ARG
a numeric function e.g. iplus, itimes, igreaterp,
exp l9cted a number.
11
ATOM TOO LONG
> 100 characters.
12
ATOM HASH TABLE FULL
no .'"oom for any more (new) atoms.
13
FILE NOT OPEN
frollil an
14
ARG NOT ATOM
15
TOO MANY FILES OPEN
l
16
1/0
function, e.g. read, print, closer.
1~cluding
16.8
teletype.
16
END OF FILE
from an input function, e.g. read, readc, ratom.
Note: the file will then be closed.
17
ERROR
call to !!.!:!!!:.
18
BREAK
control-B was typed.
19
ILLEGAL STACK ARG
a stack function expected a stack position and was
gi,ven something else.
This might occur if the
arguments to a stack function are reversed.
Also
occurs if user specified a stack position with a
function name, and that function was not found on
the stack.
20
FAULT IN EVAL
artifact
See Section 12.
of
bootstrap.
Never
occurs
after
faulteval has been defined as described earlier. ,
21
ARRAYS FULL
system will first initiate a GC: 1, and if no
array space is reclaimed, will then generate this.
error.
22
DIRECTORY FULL
no new files can be created until user deletes
some old ones and expunges.
23
FILE NOT FOUND
file name does not correspond to a file in the
corresponding directory.
Can also occur if file
name is ambiguous.
24
FILE INCOMPATIBLE - SYSIN
25
UNUSUAL CDR ARG LIST
from sysin, Section 14.
a form ends in a non-list other than NIL, e.o.
(CONS T • 3).
16.9
26
HASH TABLE FULL
seel hash link f.unctions, Section 7.
27
ILLEGAL ARG
Catch-all error.
Currently used by evala, arg,
funarg, allocate, rplstring, and sfptr.
28
ARG
NOT
ARRAY
elt or seta given an argument
that
is
not
a
pointer to the beginning of an array.
29
ILLEGAL OR IMPOSSIBLE BLOCK
from getblk or relblk.
See Section 21.
30
currently not used.
31 LISTS fULL
following a GC: 8, if a sufficient amount of list
words have not been collected, and there is
no
un-
allocated space left in the system, this error is
generated.
Many system functions,
e.g. define, arglist, advise, !.Qjz, expt,
generate errors with appropriate messages by calling
~
etc,
also
(see page 16.12)
which causes an error of type 16.
Error handling by error type
Occasionally the, user may want to treat certain error types different than
others, e.g. always break. never break, or perhaps take some corrective action.
This can be accomplished via errortypelst.
errortypelst is a list of elements
of the form (n expression). where n is one of the 28 error numbers.
breakcheck
has
been
completed,
but
before
any
other
action
is
After
taken,
errortypelst is searched for an element with the same error number as that
16.10
causing the error.
If one is found, and the evaluation of the corresponding
expression produces a non-NIL value. the value is substituted for the offender,
and the function causing the error is reeentered.
for this application, the following three variables may be useful:
errormess
~
is the error number, cadr the ·offender· e.g.
(10 NIL) corresponds to NON-NUMERIC ARG NIL error.
errorpos
position of
the
function
in which
the
error
occurred, e.g. stkname[errorpos] might be IPLUS,
RPLACA, INFILE. etc.
breakchk
va lue of breakcheck p i. e • T means a break will
occur. NIL means one will not.
for example, putting
[10 (AND (NULL (CADR ERRORHESS»
(SELECTQ (STKNAME ERRORPOS) .
«IPLUS ADDl SUB1) 0)
(ITIHE5 1)
(PROGN (SETQ BREAKCHK T) NIL]
on
errortypelst would specify that whenever a NON-NUMERIC ARG - NIL error
occurred. and the function in question was IPLU5. ADD1, or SUB1. 0 should be
used for the NIL. If the function was ITIHES, 1 should be used.
always break.
Otherwise,
Note that the latter case is achieved not by the value returned,
but by the effect of the evaluation. i.e. setting BREAKCHK to T.
(16 (SETQ BREAKCHK HIL.»
Similarly,
would prevent END OF FILE errors from ever. breaking.
16.11
16.6
Error Functions
errorx[erxm]
is the entry to the error routines.
'If erxm=NIl,
errorn[] is used to determine the error-message.
Otherwise, seterrorn[erxm] is ,performed, • setting I
the
error
and
err~rx[(10
either
(10
type
T)~
errorx
argument.
(PLUS T),
T)] or
calls
Thus
following
errorn[]
breakcheck,
and
is
either
induces a break or prints the message and unwinds
to the last errorset.
Note that errorx'can be
called by any program to intentionally induce an
error
any
of
applications,
However,
~ype.
the
function
error
\--
most
for
will
be
more
useful.
error[messl ;mess2;nobreak]
The message that is (will be) printed is mess1
(using prinl), followed by a space if messl is an
atolD, otherwise a carriage return., Then mess2 is
prilllted,
using
othtsrwise print.
print
if
mess2
a
is
string,
e. g.. errore "NON-NUMERIC ARG·; T]
will print
NON,·NUMERIC ARG
T
and
error[FOO;"NOT A FUNCTION"]
will
pri,nt
FOO NOT A FUNCTION. ,( If both mess 1 and mess2 are
NIl~
the message is simply ERROR.)
If nobreak=T,
calJLs
~
error! .
prints its message and then
Otherwise
err()rx[(17 (mess1 • mess2»],
i.e.
it
calls
generates
an
error of type 17, in which case the decision as to
16.12
whether or not to break, and whether or not to
print a message,
is handled as per any other
error'.
help[mess1;mess2]
prints mess1 and mess2 a la !!.!:.Q!:. and then calls
break1.
If both mess1 and mess2 are NJl, HElPf is
used for the message.
help is a convenient way to
program a default condition, or to terminate some
protion of a program which
theoretically
the
computation is never supposed to reach.
errort[]16
programmable control-E, i.e., immediately returns
from last errorset or resets.
reset[ ]
Programmable control-D, 1. e. immediately returns
to the top level.
errorn[]
returns information about the last error in the
form (n x) where rr is the error type number and
~
is the expression which was (would have been)
printed
out
after
the
error
message.
Thus
following (PLUS T), errorn[] is (10 T).
errormess[u]
prints message corresponding to an errorn that
yielded y.
For example, errormess[ (10 T)] would
print
NON-NUMERIC ARG
T
i6----~--~-------------------------------------------- -------------------------
Pronounced -error-bang-.
16.13
errorset[u;v]17
performs eval[u 1.
type of function,
Note that errorset is a lembdaand that
its arguments
are
evaluated be/ore it 1s entered, i.e. errorset[x]
means eval is called with the ualue of!.
In most
cases, ersetg and n lsetg (deScrib'd' below') are
more useful.
If no error occurs in the evaluation
of y, the value of errorset is a list containing
one element, the value of eval[u].
If an error
did occur, the value of errorset is NIL.
The argument y controls the printing of error
mes.sages if an error occurs.
If yeT ,the error
message is printed; if y=NIL it is not.
If y=INTERNAl, the errorset is ignored' for the
pUrjl)ose of deciding whether or not to break or
print a message.
However,
the errorset is in
effect for the purpose of flow of control,-i.e. if
an error occurs, this errorset returns NIL.
ersetq[ersetx]
nlalnbda, performs
. (ER:5ETQ (FOO»
(ERI~ORSET
nlsetq[nlsetx]
nlmnbda,
----
errorset[ersetx;t],
i.e.
equivalent
to
is
(QUOTE (FOO»
T).
performs errorset[nlsetx;NIL].
j~----------------------~-----------------~----------------------.-----~-------
errorset is a subr, so the names ·u· and ·v· don't actually appear on the
stack nor wil~ they affect the evaluation.
16.14
Index for Section 16
Page
Numbers
APPLY[FN;ARGS] SUBR ..........•••.•••••••••..•.•• 16.2
APPLY~[FN;ARGl; ... ;ARGn] SUBR..••••••••...••••• 16.2
ARG[VAR;M] FSUBR ............•...•••••••••••••... 16.10
ARG NOT ARRAY (error message) •••••••••••••••.••• 16.10
ARG NOT ATOM (error message) .................... . '16.8
ARG NOT ATOM - SET (error message) ••••••••••.••• 16.8
ARRAYS FULL (error message) .....•••••••••••••••• 16.9
ATOM HASH TABLE FUll (error message) •••••••••••• 16.8
ATOM TOO LONG (error message) •..•••••••••••••••• 16.8
ATTEMPT TO RPlAC NIL (error message) •••••••••••• 16.8
ATTEMPT TO SET NIL (error message) ••••••.••••••• 16.8
bell (typed by system) ..•..••..•••••••••.••••••• 16.2
BREAK (error message) ..•.•.•.••.•••••••••••••••• 16.9
BREAKl[BRKEXP;BRKWHEN;BRKFN;BRKCOHS;BRKTYPE] NL
16.1-3,7,13
BREAKCHECK ••.•
16.2-7,10,12
BRKEXP (break variable/parameter) ••••••••••...•• 16.1-2,4
(BROKEN) (typed by system) •••••••••••••••••••••. 16.4
control-B •..••.•.•..•••
16.3,5,7,9
control-D ••..•••
16.2,7,13
control-E .•.......•••..•.••••••
~
16.3,13
control-H ...........••....•••••••••••••••••••••• 16.2"'3
DIRECTORY FULL (error message) •••••••••••••••••• 16.9
OWIH ••••••••• '." •••••••••••••••••••••••••••••••••• 16.1
ElT[A;N] SUBR ••••••••••••••••••••••••••••••••••• 16.10
END OF FILE (error message) •.•••••••.•••••..•••• 16.9
ERROR[MESSl;MESS2;NOBREAK] •••..••••••.••••..•••• 16.6,9-10,12
ERROR (error message) .•••.•••••••••••••••••••..• 16.9
error handling •....•••••.•••••••••••••••••.••••• 16.1-14
error number •••••••.•.••••••••••••••••••••••••.• 16.7
error types ..••....•••••••.••••••••••••••••••••• 16.7
ERROR' [] SUBR ••••••••••••••••••••••••••••••••••• 16.12-13
ERRORMESS[ U]
•••••••••••••••••• .,
16.7,13
ERRORN[] SUBR .......•.•.••••••••••.•.•••••.••••• 16.7,13
ERRORSET[U;V] SUBR .......•.••.••.•....••.•••..•. 16.5-6,12-14
ERRORTYPElST (system variable/parameter) ••••.•.• 16.10-11
ERRORX[ERXH] ...........•..••..•.•••..••.••.•.•.. 16.12
ERSETQ[ERSETX] NL ...•••••••••••••••••••••••••••• 16.14
EVAl (break cominand) ••••.•••••••••••••••••••.••• 16.3-4
EVAl[X] SUBR •• ·••••••••••
16.14
eval-blip .....•..•..••...••••••••••••••••••••••• 16.5
EVALA[ X; A] SUBR ..............•..•..•...•••.•.•.• 16.10
FAULT IN EVAL (error message) ••.••••••••••••.••• 16.9
FAUlTAPPLY[FAUlTFN;FAUlTARGS] •••••.•..•.••.••••. 16.2
FAUlTEVAl[FAULTX] NL~ .......••••.••.•••••.••.•.• 16.1,9
FILE INCOMPATIBLE - SYSIN (error message) ••••••. 16.9
FILE NOT rOUND (error message) •••••••••••••••••• 16.9
FILE NOT OPEN (error message) •••••••••••••• e • • • • 16.8
FILE WON'T OPEN (error message) ••••••••••••••.•. 16.8
FUNARG
•••••••••••••••••••••••••
16.10
function definition cell ..•..•••••••••••••••.••• 16.1
function objects •.•••••••.•••••.••••.••••••••.•• 16.1
GC: 1 (typed by system) •.••••••••••••••••••••••• 16.9
GETBlK[N] SUBR ....•••...•.•.•••.••••.•••••.•• ~ •• 16.10
GO (break command) ..••.•..••••••••••.•••••••.••• 16.3-4
HASH TABLE FUll (error message) •••••.••••••••••• 16.10
HElP[HESS1;HESS2] ~ •...•••••••••••••••••••••••••• 16.13
e, • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
It
0
••••••••••••••••••••••••
• • • • • • • • "• • • • • • • • • • • • • • • • • • • • • • •
o •••••••••••••
0
0
••
................
.
.......................
.
G
••••••••••••••••
INDEX.16.1
Page
Numbers
HELP! (typed by system) .........•..••••••.••..••
HELPCLOCK (system variable/parameter) ••.•..•.•..
HELPDEPTH (system variable/parameter) •••• ~ •...•.
HELPFLAG (system variable/parameter) .••.••.•.••.
HELPTIME (system variable/lparameter) ....••....••
ILLEGAL ARG (error message) ....••••...•••.•..•••
ILLEGAL ARG - PUTD (error message) ••.•••.••.•.••
ILLEGAL OR IMPOSSIBLE BLOCK (error message)
ILLEGAL RETURN (error message) .•••••.•••••.•••••
ILLEGAL STACK ARG (error message) •••••••••••..••
IN (typed by system) ..•..•.•••.••••..•••••••••••
IN? (break command) ..........•.•.•••.••••.•.••••
input buffer ...................................... .
interpreter ............. '....................... .
INTERRUPT[INTFN;INTARGS;INTYPE] •••••.•••••.•••••
INTERRUPTED BEFORE (typed by system) ..•.••..••••
LISTS FULL (error message) ...••••••••••••••••••.
NLSETQ[NLSETX] NL .......
NOBIND
.....•..•.......•.
n
•••••••••••••••••••••••
0
•••••••••••••••••••••••
NON-NUMERIC ARG (error message) ••••..•••.•.•••.•
NONXMEM (error message) ..•.••.••••••••••••••••••
OK (break command) ........••..••••••.••....•..••
P-STACK OVERFLOW (error message) ••••.•••••••••••
property 1 is t
............ .' ... .; .................. .
RELBLK[ADDRESS;N] SUBR ..•.•.••..••••.•••.•••••••
RESE T[] SUBR ..........•...••.•••••.•.•••.•••...•
RETFROM[POSjVALUE] SUBR ...•.•••.••••.••••••••.••
RE TURN (break command) .•..••••••••••••.•..••••••
RPLSTRING[X;N;Y] SUBR •.•..•.•.••••••••••••.•••••
SETA[A;N;V]
...........••••••.•••
6
•••••••••••••••
SFPTR[FILE;ADDRESS] SUBR ...•....••.•••.•••••••••
SYSIN[FILE] SUBR ..........••.•••••••••.•••••••••
teletype initiated breaks .•.....•••....•••.•.••.
TOO MANY FILES OPEN (error message) •..••••••.•••
U.B.A. (error message) .•.....•..••.•.••••••••••.
U.0. F. (error message) •.•.•••.••.•••••••••.•••••
unbound atom ............•..•..•.•..••••••••••.••
und~fin~d function
.......••.•..••.•..•.••••....•
UNDEFINED OR ILLEGAL GO (error message) •.••.•••.
UNUSUAL CDR ARG LIST (error message) ..•.••••..•.
value cell
...... ., .............................. .
value of a break ...........••..••.•••••.•.•.•••.
7 (typed by system) ..••.•.••••••••••.•••••••.•••
t (break command)
..•..•.••••••••••••.•••••••••••
INI>EX.16.2
16.13
16.6
16.5-6
16.3-4,7
16.5-6
16.10
16.8
16.10
16.8
16.9
16.4
16.1
16.2,7
16.1
16.2
16.2
16.10
16.14
16.1
16.4,8
16.7
16.3-4
16.7
16.1
16.10
16.13
16.6
16.1,4
16.10
16.10
16.10
16.9
16.2-3
16.8
'16.1,4
16.1-2,4
16.1
16.1
16.8
16.9
16.1
16.2
16.4
16.2,7
SECTION 17
AUTOKATIC ERROR CORRECTION - THE OWl" FACILITY t
17.1
Introduction
A surprisingly large percentage of the errors made by INTERLISP users are of
the
type that could be corrected by another LISP programmer without any
information
~bout
the purpose of the program or expression in question, e.g.
misspellings, certain kinds of parentheses errors, etc.
To correct these types
of errors we have implemented in INTERLISP a OWIM facility, short for DO-WhatI-Mean.
DWIM
is called automatically whenever an
evaluation of an INTERLISP expression.
error2
occurs
in
the
OWl" then proceeds to try to correct
the mistake using the current context of computation plus information about
what the user had previously been doing, (and what mistakes he had been making)
as guides to the remedy of the error.
If DWI" is able to make the correction,
the computation continues as though no error had occurred.
Otherwise, the
procedure is the same as though DWI" had not intervened: a break occurs, or an
unwind to the last errorset, as 'described in Section 16.
The following
protocol illustrates the operation of OWl".
i-~------------~---~~~--~-~---~-~-~-------------------~---~~------------------OWl" was designed and implemented by W. Tei telman ~ It ,is discussed in
[Tei2].
2
Currently,
errors.
DWIPI only operates on unbound atoms and undefined function
17.1
Example
The user defines 8 function
f8C'~
of one argument,!.
The value of fact(n] is
to be n factorial.
(LAMBDA (N) (COND
«ZEROP N9 1) «T (ITIHES N (fACT 8SUBl N]
(fACT)
~OEFINEQ«fACT
~
Note that the definition of fa4::t contains several mistakes! Itimes and fact
have been misspelled; the 9 in
1~9
was intended to be a right parenthesis, but
the shift key was not depressed; similarly, the 8 in 8SUBl was intended to be a
left parenthesis; and finally, there is an extra left parenthesis in (ront of
th~
T that begins the final clause in the conditional.
[1]
[2]
[3]
~PRETTYPRINT«fACCT]
=PRETTYPRINT
=FACT
- (fACT
[LAMBDA (N)
(CONO
«ZEROP N9 1)
«T (ITIM5 H (FACCT 8SUBl H])
(FACT)
.
After
defining
fact,
the
uselr wishes
to
look
at
its
definition
using
PRETTYPRINT, which he unfortunately misspells.[ 1] Since there is no function
PRE TTYPRINT in the system, aU. D. F. error occurs. and DWI" is called.
DWIPI
invokes its spelling corrector, which searches a list of functions frequently
used (by this user) for the best possible match.
close,
Finding one that is extremely
DWIr1 proceeds on the a!isumption that PRETTYPRINT meant PRETTYPRINT,
notifies the user of this, [2] and calls prettyprint.
At this point, PRETTYPRINT would normally print (fACCT HOT PRIHTABlE) and exit,
since facet has no definition.
Note that this is not an INTERLISP error
17.2
condition. so that OWl" would not be called as described above.
However, it is
obviously not what the user meant.
This sort of mistake is corrected by having prettyprint itself explicitly
invoke the spelling corrector portion of DWI" whenever given a function with no
expr definition.
Thus with the aid of DWI". prettyprint is able to determine
that the user wants to see the definition of the function fact.[3] and proceeds
accordingly.
"FACT(3]
N9 [IN FACT] ->
[IN FACT] (CONO
(CONO
ITIM5 [IN FACT]
FACCT [IN FACT]
85U81 [IN FACT]
[4]
N
)?
«T
(T
YES
--») ->
--»
-) ITIHES
-> FACT
-> (SUBt? YES
[5]
6
.. pp FACT
[6]
(FACT
[LAMBDA (N)
(CONO
«ZEROP N)
1)
..FACT
(T (lTMES N (FACT (SUB1 N])
The user now calls his function fact.[4] During its execution, five errors
occur, and DWIM is called five times.[5] At each point, the error is corrected,
a message printed describing the action taken, and the computation allowed to
continue as i fno error had occurred
printed, the value of fact(3).
4
Following the last correction, 6 is
Finally, the user prettyprints the new, now
correct, definition of fact.[6]
In this particular example, the user was shown operating in TRUSTING mode,
which gives DWIM carte blanche for most corrections.
The user can also operate
in CAUTIOUS mode, in which case DWI" will inform him of intended corrections
before they are made, and allow the user to approve or disapprove of them.
17.3
For
most corrections, if the user does not respond in a specified interval of time,
DWIM
automatically
proceeds with
the correction,
user
need
intervene only when he does not approve.
Sample output is given below.
Note
that
second, and fifth questions;
DWI"
the user responded to the first,
so
that
the
responded for him on the third and fourth.
"FACT(3)
N9 [IN FACT] -) N )? YES
U.D.F. T [IN FACT] FIX?
YES
[IN FACT] (COND
«T --») ->
(COND
(T --»
ITIMS [IN.FACT] -> ITIHES?
... YES
FACCT [IN FACT] -> FACT?
•• oYES
8SUBl [IN FACT] -> (SUB1? NO
U.B.A.
(8SUBI BROKEN)
We have put a great deal of ef'fort into making DWI"
[1]
[2]
[3]
[4]
[5]
t
smart t , and experience
with perhaps fifty different users indicates we have been very successful; DWIH
seldom fails to correct an err'or the user feels it should have, and almost
never mistakenly corrects an error.
However, it is important to note that even
when OWIH is wrong, no harm is done: 3 since an error had occurred, the user
wou ld have had to intervene anyway if DWI" took no action.
mistakenly corrects
an error,
Thus, if DWI".
the user Simply interrupts or
aborts
the
computation. UNDOes the DWU1 change using UNDO described in Section 22, and
makes the correction he would have had to make without DWl".
It is this benign
quality of DWIM that makes it a valuable part of INTERLISP.
a-----------------------------------------------------------------------------Except perhaps if DWIM's correction mistakenly caused a destructive
computation to be initiated, and information was lost before the user could
interrupt. We have not yet had such an incident occur.
17.4
17.2
Interaction with OWl"
DWIM is enabled by performing either OWIH[C], for CAUTIOUS mode, or DWIH[T] for
TRUSTING mode. 4 In addition to setting dwimflg to T and redefining faulteval
and faultapply as described on page 17.14, DWIH[C] sets approveflg to T, while
OWIH[T] sets approveflg to NIL.
The setting of approve fIg determines whether
or not the user wishes to be asked for approval before a correction that will
modify
the
definition of one of his functions.
In CAUTIOUS mode,
approveflg=T. OWl" will ask for approval; in TRUSTING mode. OWIMwill not.
i.e.
for
corrections to expressions typed in by the user for immediate execution,6 OWl"
always acts as though approveflg were NIL, i.e. no approval necessary. 8 In
either case, DWI" always informs the user of its action as described below.
Spelling Correction Protocol
The protocol used by OWIM for spelling corrections is as follows:
correction
occurs
in
type-in.
print
= followed
by
the
correct
If the
spelling,
followed by a carriage-return, and then continue, e.g.
4-~-------~--~--~-----------~-~-----~--~-------------- -------------------------
INTERLISP arrives with DWIM enabled in CAUTIOUS mode. OWl" can be disabled
by executing OWIH[] or by setting dwimflg to NIL. See page 17.23.
6
Typed into lispx.
lispx is used by evalqt and break, as well as for
process ing the editor's E command.
Functions that call the spelling
corrector directly. such as editdefault (Section 9), specify whether or not
the correction is to be handled as type-in. For example, in the case of
editdcfault, commands typed directly to the editor are treated as type-in,
so that corrections to them will never require approval. Conunands given as
an argument to the editor, or resulting from macro expansions, or from IF,
LP, ORR conunands etc. are not treated as type-in, and thus approval will be
requested if approveflg=T.
6
For certain types of corrections, e. g. run-on spelling corrections, 8-9
errors t etc., dwim always asks for approval, regardless of the setting of
approveflg.
17 .. 5
user types:
DWIr.. types:
.. (5ETQ IFOO (NCOCH FIE FUM»
eNCONC
I f the correction does not occur in type-in, print the incorrect spelling.,
followed
by [IN function-name],
ITIMS [IN FACT]
->
e).
and
then
the correct
ITIHES as s;hown on page 17.3. 7 Then,
spelling.
e.g.
if approveflg=NIL.
print a carriage return, make the correction and continue. Otherwise, print a
few spaces and a ? and then wait for approval. 8 The user then has six options.
He
can:
1.
Type Y; OWl" types ES, and proceeds with the correction.
2.
Type Hi OWl" types 0, and does not make the correction.
3.
Type t; DWH1 does not :make the correction, and furthermore guarantees
that the error will not cause a break. See footnote on page 17.15.
4.
Type control-E; for error correction, this has the same effect as
typing H.
Do nothing i 1.n which celse OWIP1 will wait a specified interval, 9 and if
the use~ohas not responded, DWI" will type
followed by the default
answer.
5.
6.
Type space or carriage-return; in which case DWI" will ~ait
indefinitely. This option is intended for those cases where the user
wants to think about his answer, and wants to insure that DWI" does
not get 'impatient' and answer for him.
7-----------------------------------------------------------------------------The appearance of -) is t(t call attention to the fact that the user's
function will be or has been changed.
8
Whenever an interaction is about to take place and the user has typed
ahead, DWJr1 types severa I be lIs to warn the user to stop typing, then
clears and saves the input buffers, restoring them after the interaction is
complete. Thus if the user has typed ahead before a DWI" interaction. DWI"
will not confuse his type ahead with the answer to its question, nor will
his type ahead be lost.
9
Equal to dwimwai t seconds.
DWI" operates by dismissing for 500
milliseconds, then checking to see if anything has been typed. If not, it
dismisses again, etc. until dwimwait seconds have elapsed. Thus', there
will be a delay of at most liZ second before OWl" responds to the user's
answer.
10
The default is always YES unless otherwise stated.
17.6
The
procedure
analogous.
for
If
spelling correction on other than
the
correction
is
being
handled
INTERLISP errors
as
type-in,
is
DWI"
prints = followed' by the correct spelling, and returns it to the function that
called DWI". e.g. cFACT as shown on page 17.2.
Otherwise, DWIPI prints the
incorrect spelling, followed by the correct spelling.
Then if approveflg=NIL,
DWU1 prints a carriage-return and returns the correct spelling.
DWI" prints a few spaces and a ? and then waits for approval.
Otherwise,
The user can
then respond with Y. N, control-E, space, carriage return, or do nothing
as
described.
Note that since the spelling corrector
its~lf
is not errorset protected, typing
N and typing control-E may have different effects when the
spelli~g
corrector
is - called directly.11 The former simply instructs the 'spelling corrector to
return NIL. and lets the calling function decide what to do next; the latter
causes an error which unwinds to the last errorset, however far back that may
be.
Parentheses Errors Protocol
As illustrated earlier on page 17.3, OWIPI will correct errors conSisting of
typing 8 for left parenthesis and 9 for right parenthesis.
In these cases, the
interaction with the user is similar to that for spelling correction.
error occurs in type-in, DWI" types
user types:
DWH1 types:
lispx types:
= followed
Ir the
by the correction, e.g.
FOO aCONS FIE FUM]
CONS
(A B C 0)
~(SETQ
=(
Otherwise, OWl" prints the offending atom, [IN function-namel, ->, the proposed
1j-------------------------·--------------------------------------------------The OWl" error correction routines are errorset protection.
17.7
correction,
a
few
spaces
and
a
"
and
then
N9 [IN FACT] -> N ) , as shown on page 17.3.
waits
for
approval,
e.g.
The user then has the same six
options as for spelling correct,ion .12 If the user types Y, DWI" then operates
exactly the same as when approveflg=NIl. i.e. makes the correction and prints
its message.
U.D.F. T Errors Protocol
DWH1 corrects certain types of parentheses errors involving a T clause in a
conditional, namely errors of the form:
1.
(CONO _e) (T _e), i.e. the T clause appears outside and immediately
following the CONO;
2.
(CONO -- (--
&
(T
_e»~)"~
i.e. the T clause appears inside a previous
clause; and
3.
(CONO -- «l
around it. 13
--»),
i.e. the T clause has an extra pair of parentheses
If the error occurs in type-i.n, DWIPI Simply types T FIXED and makes the
correction.
Otherwise if approveflg=NIL, DWIPI makes the correction, and prints
a message consisting of [IN function-namel,
incorrect
forms
of
CONo,
followed
by
e).
followed by one of the above
then
on
the
next
line
the
corresponding correct form of the CONO, e.g.
12----------------------------------------------------------------------------except the waiting time is 3*dwimwait seconds.
13
For U.O.F. T errors that are not one of these three types, DWI" takes no
corrective action at all, i.e. the error will occur.
17.8
[IN FACT] (CONO
(COND
«T
(T
_e»~)
->
_e»~
as shown on page 17.3.
If approveflg=T,
ownl
prints U.D.F. T, followed by [IN function-name], several
spaces, and then FIX? and waits for approval.
The user then has the same
options as for spelling corrections and parenthesis errors.
If the user types
Y or defaults, OWl" then proceeds exactly the same as when approveflg=NIL, i.e.
makes the correction and prints its message, as shown on page 17.4.
Having made the correction, OWl" must then decide how to· proceed with the
computation.
In ca·se 1, (COND --) (T --), DWI" cannot know whether the last
clause of the CONo before the T clause succeeded or not, i.e. if the T clause
had been inside of the CONO, would it have been entered?
Therefore DWI" asks
the user 'CONTINUE WITH T CLAUSE' (with a default of YES).
If the user types
N, DWI" continues with the form after the CONo, i.e. the form that originally
followed the T clause.
In case 2, (CONo -- (-- & (T
--»), OWl" has a different problem. After moving
the T clause to its proper place, OWl" must return as the value of the COND,
the value of the expression corresponding to &.
Since this value is no longer
around, .DWI" asks the user, 'OK TO REEVALUATE' and then prints the expression
corresponding to &.
reevaluating
&,
If the user types Y, or defaults, OWIPI continues by
otherwise OWU1 aborts, and a U.O.F. T error will then occur
(even though the CONO has in fact been fixed).14
14----------------------------------------------------_____
u
__________________ _
If OWIM can determine for itself that the form can safely be reevaluated,
it does not consult the user before reevaluating. OWl" can do this if the
form is atomic, or car of the form is 8 member of the list okreevalst, and
each
of
the arguments
can
safely
be
reevaluated,
e.g.
(SETQ X (CONS (IPlUS. Y Z) W» is safe to reevaluate because SETQ, CONS, and
IPLUS are all on okreevalst.
17.9
In case 3. (CONO -- «T
--»), there is no problem with continuation, so no
further interaction is necessary.
17.3
Spelling Correction
The spelling corrector is given as arguments a misspelled word (word means
literal atom), a spelling list (a list of words), and a number:
and reI respectively.
splst,
Its task is to find that word on splst which is closest
to xword, in the sense describEtd below.
xword.
~,
This word is called a
re~pelltnf1
of
reI specifies the minimum 'closeness' between xword and a respelling.
If the spelling corrector cannot. find a word on splst closer to xword than reI,
or if it finds two or more words. equally close, its value is NIL, otherwise its
value is the respelling. 16
The exact algorithm for comput:Lng the spelling metric is described later on
page 17.20, but briefly 'closeness' is inversely proportional to the number of
disagreements between the two words, and directly proportional to the length of
the longer word, e.g. PRTTYPRNT is 'closer' to PRETTYPRINT than CS is to CONS
even though both pairs of words have the same number of disagreements.
The
spelling
the
corrector operates b:..- proceeding down splst,
and
computing
closeness between each word andl xword, and keeping a list of those that are
closest.
Certain differences
b~tween
words are not counted as disagreements,
for example a single transposit.ion, e.g. CONS to CNOS, or a doubled letter,
e.g. CONS to CONSS. etc.
In the event that the spelling corrector finds a word
on splst with no disagreements, it will stop searching and return this word as
the respelling.
Otherwise, the spelling corrector continues through the entire
i~-----------------------------------------------------------------------------
The spelling corrector can also be given an optional functional argument,
fn, to be used for selecting out a subset of splst, i.e. only those members
of splst that satisfy fn will be considered as possible respellings.
17.10
spelling list.
Then if it has found one and only one 'closest' word,
returns this word as the respelling.
For example,
spelling corrector will probably return
CONS
if xword is VONS,
as the respelling.
it
the
However, if
xword is CONZ, the spelling corrector will not be able to return a respelling,
since CONZ is equally close to both CONS and CONO.
finds
an
acceptable respelling,
If the spelling corrector
it interacts with the user as described
earlier.
In the special case that the misspelled word contains one or more al t-modes,
the spelling corrector operates somewhat differently.
Instead of trying to
find the closest word as above, the spelling corrector searches for those words
on splst that match xword, where an alt-mode can match any number of characters
(including 0). e.g. FOOl matches Foot and FOO, but not NEWFOO.
all three.
SFOOS matches
In this case, the entire spelling list is always searched, and if
more than one respelling is found, the spelling corrector prints AMBIGUOUS, and
returns NIL.
on
For example, CONS would be ambiguous if both CONS and CONO were
the spelling list.
If
t~e
spelling corrector finds one and only one
respelling, it interacts with the user as described earlier.
For both spelling correction and spelling completion, regardless of whether or
not the user approves of the spelling corrector's choice, the respelling is
moved to the front of splst.
Bince many respellings are of the type
wit~
no
disagreements, this procedure has the effect of considerably reducing the time
required to correct the spelling of frequently misspelled words.
Spelling Lists
Although any list of atoms can be used as a spelling list
p
e.g. editcomsa,
brokenfns. filelst, etc •• four lists are maintained espeCially for spelling
17.11
correction: spellings1, spellin,~, spellings3, and userwords. 18
Spellings1 is a list of functions used for spelling correction when an input is
typed
in
apply
format,
and
the
function
is undefined,
e.g.
EOTIF(FOO).
Spellings1 is initialized to cClntain defineq, break, makefile, editf, tcompl,
load, etc.
Whenever lispx is gliven an input in apply 'format, i.e. a function
and arguments, the name of the function is added to spellingsl. 17 For eX¥lple,
typing CALLS(EOITF) will cause CALLS to be added to spellings1.
Thus if the
user typed CALLS(EOITF) and later typed CALLLS(EDITV), since spellings1 would
then contain CAllS, DWI" would be sUt:cessful in correcting CALLlS to CALLS. 18
Spellings2 is a list of functions used for spelling correction for all other
undefined functions.
!!1!pend, cond, cons,
It is initialized to contain functions such as add1,
JlQ,
list,
nc~,
lispx is given a non-atomic 1rorm,
spe 11 1n9s2.
print, 1!.!:.QJl. return, setq, etc.
the name of the function
for example. typing (RETFROM (STKPOS (QUOTE FOO)
would add retfrom to spellings2.
Function names are also
Z»
add~d
Whenever
is added to
to a break
to spellings2
by define, defineq, load (when loading compiled code)e unsavedef, editf, and
prettyprint.
Spellings3 is a list of words used for spelling correction on all unbound
atoms.
Spellings3 is initialized to editmacros, breakmacros. brokenfns, and
advisedfns.
Whenever lispx is gliven an atom to evaluate, the name of the atom
---------------------~----------------------~--------------------------------~16
All of the remarks on maintaining spelling lists apply onill when DWIPI is
enabled, as indicated by dwimflg=T.
17
Only if the function has a
18
If CALllS(EDITV) were typedl before CALLS had been 'seen' and added to
spellings1. the correction would not succeed. However, the alternative to
using spelling lists is to soarch the entire oblist, a procedure that would
make spelling correction intolerably slow.
d~finition.
17.12
is added to spellings3. 19 Atoms are also added to spellings3 whenever they are
edited by editv, and whenever they are set via
~ or~.
For example,
when a file is loaded. all of the variables set in the file are added to
spellings3.
Atoms are also added to spellings3 when they are set by a lispx
input, e.g. typing (SETQ FOO (REVERSE (SETQ FIE
--»)
will add both FOO and FIE
to spellings3.
Userwords is a list containing both functions and variables that the user has
referred to e.g.
by breaking or editing.
correction by arglist,
unsavedef.
Userwords is initially NIL.
load,
(when
Userwords is used for spelling
prettyprint,
break,
editf.
advise,
etc.
Function names are added to it by define, defineq,
loading compiled code,
or
loading
unsavedef, editf, editv, editp, prettyprint, etc.
exprs
to
property
lists)
Variable names are added to
userwords at the same time as they are added to spellings3.
In addition, the
variable lastword is always set to the last word added to userwords, i.e. the
last function or variable referred to by the user, and the respelling of NIL is
defined to be the value of lastword.
Thus, if the user has just defined a
function, he can then edit it by simply typing
EDITf(~,
or prettyprint it by
typing PP().
Each of the above four spelling lists are divided into two sections separated
by a NIL. The first section contains the 'permanent' words; the second section
contains
the
temporary words.
New words are added to the corresponding
spelling list at the front of its 'temporary section. 20 (If the word is already
in the temporary section, it is moved to the front of that section; if the word
is
in
the permanent section. no action is taken.)
If the length of the
19----------------------------------------------------------------------------Onl~ if the atom has a value other than NOBINO.
20
Except that functions added to spellings1 or spellingsZ by
added to the end of the permanent section.
17.13
lis~
are always
temporary sect ion then exceeds a specified number, the las t (oldes t) word in
the temporary section is
for~otten,
i.e. deleted.
spelling lists from becoming cluttered
~ith
This procedure prevents the
unimportant words that are no
longer being used, and thereby slowing down spelling correction time.
the spelling corrector moves each word selected as a
resp~lling
Since
to the front of
its spelling list, the word is thereby moved into the permanent section.
Thus
once a word is mispelled and c:orrected, it is considered important and will
never be forgotten.
The
maximum
length
of
the
temporary section
for
spellingsl,
spellings2,
spellings3 and userwords is gi'ven by the value of #spellings1, #spellings2,
Ispellings3, and luserwords, initialized to 30, 30, 30, and 60 respectively.
Using these values, the average length of time to search a spelling list for
one word is about 4 milliseconds. 21
17.4
Error Correction
As described in Section 16, whenever the interpreter encounters an atomic form
wi th
no binding, or a non-atomic form £.!!: of which is not a function or
function object, it calls the function faulteval.
given an undefined function,
:it calls faultapply.
Similarly, when applY is
When DWI" is enabled,
faulteval and faultapply are redefined to first call dwimblock, a part of the
DWIl'I package.
If the user abclrts by typing control-E, or if he indicates
disapproval of Dwnl' s intended .:orrection by answering N as described on page
21------------------------------·----------------------------------------------If the word is at the front of the spelling list, the time required is only
1 millisecond. If the word is not on the spelling list, i.e. the entire
list must be searched, the time is proportional to the length of the list;
to search a spelling list of length 60 takes about 7 milliseconds.
17.14
17.6, or if DWI" cannot decide how to fix the error, dwimblock returns NIL.22
In this case, faulteval and faultapply proceed exactly as described in Section
16, by printing a U.B.A. or U.D.F. message, and going into a break if the
reqUirements of breakcheck are met, otherwise unwinding to the last errorset.
If
DWI"
can
(and is
allowed to) correct the error,
dwimblock exits
by
performing reteval of the corrected form. as of the posi tion of the call to
faulteval or faultapply.
Thus in the example at the beginning of the chapter,
when DWI" determined that ITIHS was ITIHES misspelled, DWI" called reteval with
( IT IMES N (FACeT 8SUB 1 N». Since the interpreter uses the value returned by
faulteval exactly as though it were the value of the erroneous
fOnD,
the
computation will thus proceed exactly as though no error had occurred.
In addition to continuing the computation, DWI" also repairs the cause or the
error whenever possible. 23 Thus 1n the above example, DWI" also changed (with
rplaca) the expression (ITIHS N (FACeT 8SUBl N»
that caused the error.
Error correction in DWI" is divided into three categories: unbound atoms,
undefined cars of form, and undefined function in!!llix.
Assuming that the
user approves if he is asked, the action taken by DWI" for the various types of
errors in each of these categories is summarized below.
The protocol of DWIM'$
interaction with the user has been described earlier.
22------------------------------------·---------------------------------------If the user answers with t, (see page 17.6) dwimblock is exited by
performing reteval[FAULTEVAL;(ERRORt)]. i.e.
position of the call to faulteval.
23
an error is generated at the
If the user's program had computed the form and called eval, e.g. performed
(EVAl (LIST X V»~ and the value of x was a miss'pel1ed function; it would
not be possible to repair the cause of the error, a1 though DWI" could
correct the misspelling each time it occurred.
17.15
Unbound Atoms
1.
If the first character of the unbound atom is " OWIPI assumes that the user
(intentionally) typed latolD for (QUOTE atom) and makes the appropriate
change. No message is typed, and no approval requested.
If the unbound atom is just • itself, OWIH assumes the user wants the next
expression
Quoted,
e.g.
(CONS X '(A B C»
will
be
changed
to
(CONS X (QUOTE (A B C»). A.gain no message will be printed or approval
asked. (If no expression follows the " OWIPI gives up.)
2.
If CLISP (Section 23) is enabled, and the atom is part of a CLISP
construct, the CLISP transformation is performed and the result returned,
e.g. N-l is transformed to (SUB1 N).
3.
If the atom contains an 8, OWIH assumes the 8 was intended to be a left
parenthesis, and calls thE! editor to make appropriate repairs on the
expression containing the atom. OWIH assumes that the user did not notice
the mistake, i.e. that the entire expression was affected by the missing
left parenthesis. For example, if the user types
(SETQ X (LIST (CONS 8CAR Y) (COR Z» V), the expression will be changed to
(SETQ X (lIST (CONS (CAR Y) (COR Z» Y».
The 8 docs not have to be t.he first character of the atom, e.g. DWI" will
handle (CONS X8CAR Y) correctly.
4.
If the atom contains a 9, OWIPI assumes the 9 was intended to be a right
parenthesis and operates as in number 3.
5.
I f the a tom begins with a 7, the 7 is treated as a', e. g. 7FOO becomes
'FOO, and then (QUOTE FOO).
6.
I r the atom is an edi t command (a member of edi tcomsa), and the error
occurred in type-in. the f!ffect is the same as though the user typed
[OITF(). followed by the atom, i.e. ' OWIPI assumes the user wants to be in
the editor editing the la~.t thing he referred to. Thus, if the user
defines the function foo and then types P, he will see =FOO, followed by
EDIT, followed by thepril1ltout associated with the execution of the P
command. followed by *, at w'hich point he can continue editing foo.
7.
If dwimuserfn=T. OWIM calls dwimuserfn, and if it returns a non-NIL value,
DWH1 returns this value. dw'imuserfn is discussed below.
8.
If the unbound atoms occurs in a function, OWIPI attempts spelling
correction using as a spelling list the list of lambda and prog variables
of the function.
9.
If the unbound atom occurred in a type-in to a break, DWI" attempts
spe lling correction using 'the lambda and prog variables of the broken
function.
10. Otherwise, DWI" attempts spelling correction using spellings3.
If all fail, DWIM gives up.
17.16
Undefined car of Form
1.
If car of the form is T, DWIM assumes a misplaced T clause and operates as
described on page 17.B.
2.
If
car
of
the
form
is
F IL,
OWIM
chcanges
the
FIl
to
FUNCTION(LAMBOA,e.g. (F/L (Y) (PRINT (CAR V»)
is
changed
to
(FUNCTION (LAMBDA (V) (PRINT (CAR V»~). No message is printed and no
approval requested. If the user omits the variable list, DWI" supplies
(X), e.g. (F/L (PRINT (CAR X») becomes
(FUNCTION (LAMBDA (X) (PRINT (CAR X»». DWIM determines that the user has
supplied the variable list when more than one expression follows FIL, £!r
of the first expression is not the name of a fUnction. and every element in
the first expression is atomic. for example, OWl" will supply (X) when
correcting (F/L (PRINT (CDR X» (PRINT (CAR X»).
3.
If car of the form is If, if, or one of the ClISP iterative statement
opera tors. e. g. FOR, WHILE. 00 at ai, the indicated transformation is
performed, and the result returned as the corrected form.
4.
I f car of the form has a function definition. OWIH attempts spelling
correction
on ~ of the definition using the
spelling
list
(LAMBDA NLAMBDA).
5.
If car of the form has an EXPR property, OWl" prints car of the form,
followed by 'UNSAVED', performs an unsavedef. and continuos. No approval
is requested.
6.
If car of the form has a property FILEDEF, the definition is to be found on
a fi Ie. If the value of the property is atomic, the entire file is to be
loaded.
I f a 1 is t, car is the name of the fi Ie and cdr the re levan t
functions, and loadfns will be used. OWl" first checks to-$ee if the file
appears in tbe attached directory, 's directory. or XTR. 31
17.7
DWI" Functions
dwim[x]
If
~=NIL,
disables DWI"; value is NIL.
If !=C,
enables DWIM in cautious mode; value is CAUTIOUS.
If !=T. enables DWnl in trusting mode; value is
TRUSTING.
For all other values of !. generates an
error.
dwimify[x]
!
is a (orm or the name of a function.
dwimify
performs all corrections and transformations that
would occur if ! were actually run.
dwimify is
undoable.
ow
edit macro.
addspell[x;splst;n]
Adds !
dwimifies current expression.
to one of the
four spelling
lists
as
and
to
follows: 32
if
splst=NIL.
spellings2.
adds
!
to
userwords
Used by def1neq.
81-----------------------------------·----------------------------------------Transpositions are also not counted when fastypeflg=T, for example, IPULX
and IPLUS will be in 80X agreement with fastypeflg=T, only 60X with
fastypeflg=NIL. The rationale behind this is that transpositions are much
more common for fast typists, and should not be counted as disagreements,
whereas more deliberate typists are not as likely to combine tranpositions
and other mistakes in a single word, and therefore can use more
conservative metric~ fastypeflg is initially NIL.
32
If ?f is already on the spelling list, and in its temporary section,
addspell moves! to the front of that section. See page 17.13 for complete
description of algorithm for maintaining spelling lists •
. 17.23
If splst=O, adds! to userwords.
loading exprs to property 1 is ts.
wh~m
If
splst.t,
adds !
per'manent section).
if
Used by load
splst=2,
to
(at
end
of
(at
end
of
Used by lispx.
adds !
permanent section).
spellingsl
to
spellingsZ
Used by lispx.
If splst=3, adds! to userwords and spellings3.
llist can also be a spelling list, in which case !!.
is the (optional) length of the temporary section.
addspell sets lastword to ! whensplst.NtL, 0 or'
3.
If !
is not a literal atom,
addspell takes no
action.
misspelled?[xword; rei ;splst; fig; 'tail; fn]
If
prints
xword=NIL
= followed
or
alt-mode,
misspelled?
by the value of lastword,
and
returns this as the respelling, without asking for
app.-oval.
Otherwise, misspelled? checks to see if
~'d
is really misspelled, i.e. if fn applied to
~~
is true, or xword is already contained on
spls~.
In this case, misspelled? simply returns
~~.
Otherwise misspelled? computes and returns
fix,s.pell[xword ;rel ;splst: fIg; tail ;fn].
17.24
fixspall[xword;rel;splst;flg;tail;fn]33
The value of fixspell is either the respelling of
xword
or
NIL.
interactions
fixspell
performs
described
all
of
the
including
earlier,
requesting user approval if necessary.
If xword=NIL or :I (al t-mode) t the respelling is
the
value
of
lastword.
and
no
approval
is
requested.
If !!i=NIL, the correction is handled in type-in
mode, i.e. approval is never requested p and xword
is not typed.
If !!.U=T, xword 15 typed (before
the .) and approval 15 requested if approveflgaT.
If
tail
is
successful,
not
NIL,
£!t of
and
the
tail \ is
respelling (using Irplaca).
correction
replaced
by
is
the
In addition, fixspell
will correct misspellings caused by running two
words together. 34 In this case, £!! of tai I is
replaced by the
two words,
fixspell
first
is
the
one.
and
For
the
value
of
example,
if
fixspell is called to correct the edit cOlIIDand
(HOVE TO AFTERCOND 3 Z) with tail=(AFTERCOND 3 Z),
1!il wou ld be changed to (AFTER COHD
Z 3).
and
33---~---~-·----------------------~-----------~---------~-------------------~--
fixspell has some additional arguments, for internal use by DWI".
34
In this case, user approval is always requested., In addition, if the first
word contains either fewer than 3 characters, or fawer characters than the
second word, the default will be N.
17.25
fixspell
would
return.
~FTER
(subject
to
user
apl)roval where necessary). 36
flJcspell generates an error if xword is already on
!l!Jls t .
The time required for a call to fixspell with a spelling list of length 60 when
the entire list must be searched is .5 seconds.
If fixspell determines that
the first word on the spellingl list is the respelling and does not need to
search any further, the time required is .02 seconds.
In other words, the time
required is proportional to the number of words with which xword is compared,
with the time for one comparisol1l, i.e. one call skor. being roughly .01 seconds
(varies slightly with the number' of characters in the words being compared.)
The function chooz is provided for users desiring spelling correction without
any output or interaction:
chooz[xword;rel;sPlst;tail;tieflg;fnl38
cor'rected
per·forms
The
spelling
no
of
value
of chooz is the
xword37 or NIL; chooz
interaction
and
no
output.
If
tief!D=T and a tie occurs, i.e. more than one word
on splst is found with the same closeness, chooz
returns the first word.
If tieflg=NIL, and a tie
occurs, chooz returns NIL.
a5-----------------~---------------------------------- -------------------------
If tail=T, fixspell will also perform run-on corrections, returning a
dotted pair of the two words in the event the correction is of this type.
36
chooz has some additional arguments, for internal use by DWI".
87
chooz does not perform spelling completion, only spelling correction.
17.26
If
tail
is
misspelling
not
NIL,
ccmsisting
together, e. g.
chooz
of
(BREAKFOO)
will
correct
running
two
a
words
for (BREAK FOO). The
value of chooz in this case is a dotted pair" of
the two words, e.g. (BREAK. FOO).
Both DWI" and
the editor use this option.
fncheck[fn;no~essflg;spellflg]
The task of fncheck is to check whether fn is
the name of a function and if not, to correct its
spelling. a8 If fn is the name of a function or
spelling correction is successful, fncheck adds
the (corrected) name of the function to userwords
using addspell. and returns it as its value.
nomessflg
informs
fncheck
whether
or
not
the
calling function wants to handle the unsuccessful
case: if nomessflg is T. fncheck simply returns
NIL, otherwise it prints fn NOT A FUNCTION and
generates a non-breaking error.
fncheck
calls misspelled?
correction,
so
that
if
lastword will be returned.
to
misspelled?' s
fourth
to
perform
fn=NIL,
the
spelling
value
of
spelIflg corresponds
argument,
flo:.
If
spellflo=T. approval will be asked if DWI" was
enabled in CAUTIOUS mode, i.e. if approveflg-T.
38----~-~------~-------·-~--------------------~---------------~----~-----------
Since fncheck is called by many low level functions such as arglist,
unsavedef, etc.. spelling correction only takes place when dwimflg=T. so
that these functions can operate in a small INTERLISP system which does not
contain OWl".
17.27
fncheck is currently used by argl1st, unsavedef, prettypr1nt, breakO, breakin,
chngnm,
advisf!,
printstructur'~.
firstfn,
lastfn,
calls,
and
edita.
For
example, breakO calls fncheck with nomessflg-T since if fncheck cannot produce
a function, breakO wants to define a dummy one.
printstructure however calls
fncheck with nomessflg=NIL, since it cannot operate without a function.
Many
other
system
functions
call misspelled? or
rixspell
directly.
example. breakl calls fixspell on unrecognized atomic inputs before
For
attem~tin~
to evaluate them, using as a spelling list a list of all break commands.
Similarly. lispx calls fixspell on atomic inputs using a list of all lispx
commands.
When unbreak is given the name of
8
function that is not broken, it
calls fixspell with two different spelling lists, first with brokenfns, and if
that fails. with userwords.
spelling list.
call misspelled?
!!!Iakefile calls m'isspelled? using filelst as a
Finally. load, bcompl, brecompile, tcompl, and recompile all
if their input file(s) won't open.
17.28
Index for Section 17
Page
Numbers
AOOSPELL[X;SPLST;N] .......•..•.•••••••••••..••.•
alt-mode (in s~elling correction) •••.•••••••••••
AMBIGUOUS (typed by dwim) •.•••••••••.•••••••••••
approval (of dwim corrections) ••.•••.•••••.•••••
APPROVEFLG (dwim variable/parameter) ••.•••••••••
be 11 (typed by dwim) .....••....•..••.•••.••.••••
BREAK1[BRKEXP;BRKWHEN;BRKFN;BRKCOMS;BRKTVPE] NL
BREAKCHECK
............................. "•••••••••••
BROKENFNS (break variable/parameter) .•••••••••••
CAUTIOUS (OWIM mode) ....•..••.•.••...•••••••••••
CHOOZ[XWORO;REL;SPLST;TAIl;TIEFLG;FN;NOBLS~CLST] ••
CLISP
......•........... '...•..••.....•.•..••••.••
CONTINUE WITH T CLAUSE (typed by dwim)
control"E
OW (error message)
DWIM[X]
OW 1M
•••••.••••
................... _.............•......
....•.••••••••.•••••.•••••••••
......................................... .
•••.••••••••••••••••••••••••••••••••••••••••
OWIM interaction with user
DWIH variables
..
I
•••.••••••••••••••••••
.•••••••••••••••••••••••••••••••
OWIMFLG (dwim variable/parameter) •••••••••••••••
OWIMIFV[X;L] ...•.............•..•.••.•••••••••.•
OWIMUSERFN (dwim variable/parameter) ••.•••••••••
OWIMWAIT (dwim variable/parameter) ••••••••••••••
EOITCOMSA (editor variable/parameter) •••••••.•••
EOITCOMSl (editor variable/parameter) •••.•••••••
EDITDEFAUL T
....•..
flo
•••••••••••••••••••••••••••••
error correction ....•.••.•••••••••••••••••••••••
ERRORSET[U;V] SUBR •.•.••••••.••••.••••••••••••••
EXPR (property name) ..•.•.••.•••••••••••••••••••
FI L
•••••••••••••••••••••••••••••••••••••••••••••
FASTVPEFLG (dwim variable/parameter) .•••••••••••
FAULTAPPLY[FAULTFN;FAUlTARGS] •.••.••••.•••••.•••
FAUL TEVAL[ FAUL TX] NL* ...•.•.••••••.••.••••.•.•••
FIlEOEF (property name) ..•...•.........•••••••••
FILELST (file package variable/parameter) •••••••
FIXSPELl[XWORO;REL;SPLST;FLG;TAIL;FNjCLST;
APPROVALFlG] ......•...••.•.••••••••••.••
FNCHECK[FN;NOMESSFLG;SPELlFLG;PROPFLG] ••••••.•••
LASTWORO (dwim variable/parameter) ••••••••.•••••
LISPX
............... ".................•••••.••••.
MAKEFILE[FILE ;OPTIONS] .........•••••.••••••••••.
MISSPELLEO?(XWORO;REL;SPLST;FLG;TAIL;FN] ••••••••
MOOEL33FLG (dwim variable/parameter) •••••••
OK TO REEVALUATE (typed by dwim) ••••••••••••••••
OKREEVALST (dwim variable/parameter) ••••••••••••
RETEVAL[POS;FORM] SUBR ...•••••••••••••••••••••••
run-on spelling corrections •••••.•••••••••••••••
SHALL I LOAD (typed by dwim) ••••••••••••••••••••
00 • • •
SKOR
•..........•..••••.•••••••••••••••••••••••••
spelling completion ...•. e • • • • • • • • • • • • • • • • • • • • • • •
spelling correction protocol ••••••••••••••••••••
spelling corrector •.•••.•••.••••••••••••••••••••
spelling lists ...............•..•.••••••••••.•••
SPELLINGSl (dwim variable/parameter) ••••••••••••
SPELLINGSZ (dwim variable/parameter) ••••••••••••
SPELLINGS3 (dwim variable/parameter) ••••••••••••
INDEX.17.1
17.23-24,27
17.11,25
17.11
17.3,5,25
17.5,18,25,27
17.6
17.28
17 .. 15
17.28
17.3,5,23,27
17.20-21,26
17.16-18
17.9
17.6-7,14
17.23
17.5,23
17.1-28
17.5
17.19
17.5,12,21
17.23
17.16-19
17.6,8
17.16,18
17.17-18
17.5
17.1-28
17.15
17.17-18
17.17
17.23
17.5,14-15,19
17.5,14-15,19
17.17-18
17.28
17.25-26,28
17.27
17.13,24-25,21
17.5,12 .. 13,28
17.28
'17.24,27 .. 28
17.21
17.9
17.9
17.15
17.5,25-27
17.17
17.21-22
17.11
17.5-7
17.2,10,20,26
17.11-14
17.12-14,18,24
17.12-14,18,23-24
17.12,14,16,24
Page
Numbers
T FIXEO (typod by dwim) ..•.••.•••••..••••.••••••
TRUSTING (OWIH mode) ..•.•.•..•••••••••.••.••••••
U.S.A. (error message) ..•.•••••.••••.••••••••.••
U.O.F. (error message) ....•••...••••••••••••.•••
U.O.F. T (typed by dwim) •.•.•.•.••••••••••.••.••
U.O.F. T FIX? (typed by dwim) •..•.••.•••••••••••
unbound a tom .........•..•..••••.•••••••••••••••.•
undefined function .......•.•..•.••••.• ' ••••••••••
UNDO (prog. asst. command) .•••••••••••••••••••••
UNSAVEO (typed by dwim) ...••••••.•.•••••••••••••
UNSAVEOEF[ X; TYP] ...................•••••••.•••••
USERWOROS (dwim variable/parameter) •..••••••••.•
ISPELLINGSI (dwim variable/parameter) .••••••••••
ISPELLINGS2 (dwim variable/parameter) •••.•••••••
ISPELLINGS3 (dwim variable/parameter) •••••••.•••
IUSERWOROS (dwlm variable/parameter) ••••••••••••
S (alt-mode) (in spelling correction) •••.•••.••.
•
•
••••••••••••••••••••••
It
•••••••••••••••••••••••
-) (typed by dwim) ....•...•••••••.••.••••••••..•
. .. (typed by dwim) ............................. .
7
8
9
=
(instead of I)
........
u
•••
j9
•••••••••••••••••••
(instead of left parenthes1s) .••••••••••••••••
(instead of right parenthesis) ••••••••.•••••••
(typed by dwim)
•••••••.' •••••••••••••••••••••••
? (typed by dwim) ...••••.••••.••••••••••••••••••
INOEX.17.2
17.8
17.3,5,23
17.15
17.2,15
17.8
17.8
17.14-18
17.14-18
17.4
17.17-18
17.17-18
17.13-14,23,27-28
17.14
17.14
17.14
17.14
17.11,25
17.16
17.3-4,6-7
17.4,6
17.16
17.2,7,16-18
17.2,7,16-17
17.5,7
17,.6-7
SECTION 18
THE COMPILER AND ASSEMBLER1
18.1
The Compiler
The compiler is available in the standard INTERLISP system.
It may be used to
compile individual functions as requested or all function definitions in a
standard format LOAD file.
The resulting code may be stored as it is compiled,
so as to be available for immediate use, or it may be written onto a file for
subsequent loading.
The compiler also provides a means of specifying sequences
of machine instructions via ASSEMBLE.
The most common way to use the compiler is to compile from a symbolic
(prettydef)
fi.le,
producing a corresponding file which contains a set of
functions in compiled form which can be quickly loaded.
An alternate way of
using the compiler is to compile from functions already defined in the user's
INTERLISP system.
In this case, the user has the option of specifying whether
the code 1s to be saved on a tile for subsequent loading, or the functions
redefined, or both.
In either case, the compiler will ask the user certain
questions concerning the' compilation.
The first question is:
1-----------------------------------------------------------------------------The compiler itself,' i.e. the part that actually generates code, was
written and documented by. and is the responsibility of A.K. Hartley. The
user interfaces, i.e. tcompl,. recompile, bcompl, and brecompile, were
written by W. Teitelman.
18.1
LISTING?
The answer to this question controls the generation of a listing and is
explained in full below.
However. for most applications, the user will want to
answer this Question with either ST or
E.
which will also specify an answer to
the rest of the questions which would othe,rwise be asked.
ST means the user
wants the compiler to STore the new definitions; E means the user is only
interested in compiling to a Eile. and no storing of definitions is perfonmed.
In both cases, the compiler will then ask the user one more question:
OUTPUT FILE:
to which the user can answer:
N or NIL
no output file.
File name
file is opened if not already opened. and compiled code
is written on the file.
Example:
FACTI FACTZ»
LISTING? 5T
OUTPUT FILE: FACT.COM
(FACT COMPILING)
~COMPILE«FACT
(FACT REDEFINED)2
(FACT2 REDEFINED)
(FACT FACTI FACT2)
j------~----------------------------------------------------~------------------
compi ler output and error messages are explained on 'page 18.48-52.
18.2
This process caused the functions FACT. FACTI, and FACiz to be compiled,
redefined, and the compiled definitions also written on the file FACT.COM for
subsequent loading.
18.2
Compiler Questions
The compiler uses the free variables Iaprlg, strf, svflg, lcfil and Istfil
which determines various modes of operation.
answers to the
'compset' questions.
These variables are set by the
When any of the top level compiling
functions are called, the function compset is called which asks a number of
questions.
V, or T
Those that can be answered 'yes' or 'no' can be answered with YES,
f~r
YES; and NO, N, or NIL for NO.
1.
The questions are:
LISTING?
The answer to this question controls the generation of a listing.
Possible
answers are:
1
Prints output of pass 1. the LAP macro code. 8
2
Prints output of pass 2, the machine code.
YES
Prints output of both passes.
NO
Prints no listings.
The variable lapflgis set to the answer.
If the answer is affirmative,
compset will type FILE: to allow the user to indicate where the output is to be
written.
The variable 1stfil is set to the answer.
3---------~--------~--------------------~------------- -------------------------
The LAP and machine code are usually not of interest but can be helpful in
debugging macros.
18.3
There are three other possible answers to LISTING? - each of which specifies a
complete mode for compiling.
They are:
S
Same as last setting.
F
Compile to [ile (no definition of functions).
ST
STore new definitions.
Implici t in these three are the answers to the questions on disposition of
compiled code and expr's, so questions Z and 3 would not be asked if 1 were
answered with S, F. or ST.
z.
REDEFINE?
YES
Causes each function to be redefined as it is compiled.
The
compiled code is stored and the function definition changed.
The variable strf is set to T.
NO
Causes function definitions to remain unchanged.
The variable
strf is set to NIL.
The answer ST for the first question implies YES for this question, F implies
NO, and S makes no change.
3.
SAVE EXPRS?
I f answered YES, svflg is set to T, and the exprs are saved on the property
1 is t
of the function name.
Otherwise they are discarded.
the first question implies YES for this question, F
change.
18.4
impl~es
The answer Sf for
NO, and S makes no'
OUTPUT FILE:
4.
If the compiled definitions are to be written for later loading, you should
provide the name of a file on which you wish to save the code that is
generated.
If you answer T or TTY:, the output will be typed on the teletype
(not particularly useful).
done.
If you answer N, NO, or NIL, output will not be
If the file named is already open, it will continue to be used.
The
free variable lcfil is set to the name of the file.
18.3
Nlambdas
When compiling the call to a function, the compiler must prepare the arguments
to the function 1n one of three ways:
1.
Evaluated (SUBR, SUBR*, EXPR, EXPR*. CEXPR, CEXPR*)
2.
Unevaluated, spread (FSUBR. FEXPR, CFEXPR)
3.
Unevaluated. not spread (FSUBR*, FEXPR*, CFEXPR*)
In attempting to determine which of these three is appropriate, the compiler
will first look for a definition among the functions in the file that is being
compiled.
If the function is not contained there, the compiler will look for
other information which can be supplied by the user by including nlambda
nospread functions on the list nlama (for nlambda !toms), and including nlambda
spread functions on the list nlaml (for nlambda list), and including lambda
functions on the list lams. 4 If the function is not contained in the file,6 or
4-~----------------------------------------------------------~---~----~--------
Including functions on lams is only necessary to override in-core nlambda
defini tions, since in the absence of other information, the compiler
assumes the function is a lambda.
6
The function can be defined anywhere in any of the files given as arguments
to bcompl, tcompl. brecompile or recompile.
18.5
on
the list nlama, nlaml, or lams, the compiler will look for a current
definition.
If the function is defined, its function type is assumed to be the
desired type.
If it is not defined, the compiler assumes that the function 1s
of type I, i.e. its arguments are to be evaluated. 6 7 In other words, if there
are type 2 or 3 functions callod from the functions being compiled, and they
are only defined in a separate file, they must be included on nlama or nlaml,
or
the
compiler will
incorrectly assume that
their arguments
evaluated, and compile the calling function correspondingly.
are
to
be
Note that this is
only necessary if the compiler does not 'know' about the function.
If the
function 1s defined at compile time, or is handled via a macro, or is contained
in the same group of files as the functions that call it, the compiler will
automatically handle calls to that function correctly.
18.4
Globalvars
Another top level free variable that affects compilations is globalvars.
Any
variables that appear on the list globalvars, and are used freely in a compiled
function,
reference
are always accessed 1through their value cell.
to
the
value
of
this
variable
In other words, a
is
equivalent
to
(CAR (QUOTE variable», regardless of whether or not it appears on the stack,
~-----------------------------~---------------------------------~~-------~-----
Before making this assumption, if the value of compileuserfn is not NIL,
the compiler calls (the value of) compileuserfn giving it as arguments cdr
of
the
form
and
the
form
itself,
i.e.
the
compiler
does
(APPlY~ COMPIlEUSERFN (COR form) form).
If a non-NIL value is returned, it
is compiled instead of form. If NIL is returned, the compiler compiles the
original expression as a call to a lambda-spread that is not yet defined.
CLISP (Section 23) uses compileuserfn to tell the compiler how to compile
iterative
statements,
IF-THEN-ElSE statements,
and
pattern
match
constructs.
7
The names of functions 50 treated are added to the list alams
(for assumed lamdas). alams is not used by the compiler; it is maintained
for the user's benefit,~ so that the user can check to see whether any
incorrect assumptions were made.
18.6
i.e.,
the stack is not even searched ror this variable when the compiled
function
is
entered.
Similarly,
(SETQ variable value)
is
equivalent
to
(RPLACA (QUOTE variable) value); i.e., it sets the top-level value.
All system parameters, unless otherwise specified, are GLOBALVARS,
i.e. are
members of the list globalvars, e.g. brokenfns, editmacros, Irpars, dwimflg. et
al. 8 Thus, rebinding these variables will not affect the behavior of the
system: instead, the variables must be reset to their new values. and if they
are to be res tored to their original values. reset again.
For example, the
user might write .•. (SETQ globalvar new-value) form (SETQ globalvar old-value).
Note that in this case, if an error occurred during the evaluation of form, or
a
control-D was typed.
original value.
the global variable would not be restored to its
The function resetvar (described in Section
convenient way of resetting global variables in such
8
5)
provides a
way that their values
are restored even if an error occurred or control-D is typed.
18.5
Compiler Functions
Note: when a function is compiled from its in core definition,
compile (and certain calls to
re~ompile),
i.e.. via
as opposed to \compl (which uses the
defini tions on a file), and the function has been modified by break, trace,
breakin, or advise, it is restored to its original state, and a message printed
out, e.g., FOO UNBROKEN. Then, if the function is not defined as an expr, its
property list is searched for the property EXPR (see savedef, Section 8).
If
there is a property EXPR, its value is used for the compilation, otherwise, the
compiler prints (fn NOT COHPILEABLE), and goes on to the next function.
8-----------------------------------------------------------------------------Since the stack does not have to be searched to find the values of these
variables, a considerable savings in time is aChieved, especially for deep
computations.
18.7
compile[x;flg]
~
Jls a list of functions (if atomic, list[x] is
use,d).
compile first asks the standard compiler
que!sti()ns, and then compiles each function on !.
using its in-core definition.
Value is !.
If compiled definitions are being dumped to a
file. the file is closed unless f!H=T.
compilel[name;def]
comlpiles def. redefining!!!!!!! if strf=T. 9 compile1
is used by compile. tcompl, and recompile.
dwimifycompflg
is T,· or def contains
If
CLISP
a
declaration, def is dwimified before compiling.
See Section 23.
tcompl[f.tles]
tcompl is used to 'compilefiles'
symbolic
load
file
(e.g..
i.e., given a
t
one
created
by
prettydef) t it produces a file that contains the
same S-expressions as the original symbolic file,
except
that every defineq
corresponding
compiled
is
replaced
by
definitions.
the
This
'compiled' file can be loaded into any INTERLISP
system with load.
fil!! is a list of symbolic files to be compiled
(if atomic, list[files] is used).
standard
compiler
OUTPUT FILE:
Instead,
questions,
the
tcompl asks the
except
output
from
for
the
compilation of each symbolic file is written on a
9------------------·-----------------~---------------------------------------~-
strf is one of the variables set by compset, described earlier.
18.8
file of the same name suffixed with COM, e.g.,
tcompl[(SYMl SYMZ)] produces two files, SYM1.COM
and SYMZ.COM. 10
tcompl processes each file one at a time, reading
in
the entire file.
Then,
for
each
DEFINEQ,
tcompl adds any NLAHBDA's in the DEFINEQ to nlama
or nlaml,11 and adds lambdas to the list lams,12
so that calls to these functions will be compiled
correctly.
Expressions beginning with DECLARE can
be used to affect the compilation, e.g. set up
MACROS.
tcompl evaluates each expression in (cdr
of) the DECLARE, presumably for effect .18 tcompl
then compiles each function
in
the
DEFINEQ's.
finally, all other expressions in the file, e.g.
RPAQO's, DEFLIST's, etc., are written onto the
output f11e. 14
io----------------------------------------------------------------------------The file name is constructed from the name field only,
e. g.
tcompl[nly.13
treepaths[x;y;type;must;avoid;only]
Like paths,
except prints paths as a'
treo structure. as shown at [6] in Figure 20-3.
must, avoid, and only have the same meaning
as 'fith paths. 14
~,
13--~~~~~~----;-;----~;ii;~-----;~;----~~~i1;h----~~~~-;;----;;----~~~-----f~;~:
"WHAT ARE THE PATHS FROM x TO y?". Such questions can be modified with
subordinate clauses to indicate values for must, avoid, and/or only, e.g.
"WHAT ARE THE PATHS FROM FOO TO FIE WHICH ONLY GO THROUGH FOOFNS AND AVOID
FIEFNS?"
14
treepaths is called for Engli,sh inputs of the form "SHOW ME HOW x CALLS y",
"DISPLAY THE PATHS FROM x TO y., etc.
20.16
lookat[x]
Builds the initial data base describing the system
~,
where
~
is either the name of a function, the
name of a variable which evaluates to a list of
functions,
clumpget[object;relation;universe)
o~
the list of functions itself.
Value is a list of objects (functions or
variables) which have the indicated relation with
respect
to
returns
a
object,
list
of
clumpget[X;SMASHERS)
e.g.
clumpget[FOO;CALLERS)
functions
a
list
of
that
call
FOO,
functions
that
smash the variable X, etc. A complete list of the
possible values for relation is given below. 16 ·
object can be a list of objects (or a variable
which evaluates to a list of objects),
in which
case the value returned by clumpget is the list of
all objects which have the indicated relation to
anu of the members of object.
Similarly.
unive~
can be a list of objects (or a
variable which evaluates to a list of objects}, in
which case the value returned by clumpget is the
list of all objects in universe which have the
indicated
relation
members
to
object
of
(or
any
of
object),
the
e.g.
clumpget[X;SMASHERS;FOOFNS).
i5--i;-~~~~~~~~--;;-;;;~~-;-~~;~~-~~~--;;;;;;;;-~~~~-~~-~~~~--;;;-;~~~~~;;~:-~~
will attempt spelling correction, and if that fails, generate an error.
If
given a valuo for object that it has not seen before, it will type "I don't
know anything about object, shall I analyse a system?" and go into analysis
mode.
'
20.17
Finally"
universe can be a relation, which is
equivalent to supplying clumpget[object;universe]
in place of object, i.e. the value returned is the
list of all objects which
have
the
indicated
relation to any of the members of the {set of all
objects which bear the relationship universe to
object} .
For
example,
clumpget[FOO;CALLERS;CALLEOFNS] is a list of all
functions that call any of the functions (CALLERS)
that
are
directly called
by
clumpget[FOO;FREEUSERS;LOCALVARS]
FOO
(CALLEOFNS).
is a
list
of
functions that use freely any of the variables
that are bound locally.by FOO.
Currently. the following relations are implemented:
CALLERS
list of functions that directly call object.
CALLEOFNS
list of functions directly called by object.
CALLCAUSERS
list
of
functions
indirectly.
CALLSCAUSEO
list
of
call
In
called
English:
by
object,
"WHO
DOES
SOMEHOW?"
ABOVE
union of object with CALlCAUSERS.
BELOW
union of object with CALLSCAUSED.
ARGS
arguments of object.
20.18
object,
perhaps
In English: "WHO CALLS FOO SOMEHOW?".
functions
indirectly.
that
perhaps
FOO
CALL
ARGBINOERS
list of functions that have object as an argument.
LOCALVARS
list
of
variables
that
are
locally
bound
in
object, e.g. PROG vars.
LOCALBINOERS
list of functions that bind object as a local
variable.
FREEVARS
list of variables used freely by object.
FREEUSERS
list of functions .that use object freely.
LOCALFREEVARS
list of variables that are used freely in object,
but are bound in object before they are used, e.g.
clumpget[FOOiLOCALFREEVARS;BELOW] gives a list of
those variables used freely below FOO,
but are
bound above the place that they are used .16 In
English: "WHAT ARE THE LOCAL fREE VARS (VARIABLES)
BELOW FOO?"
GLOBALFREEVARS
list of variables used freely in object without
previously being bound in object.
ENTRYFNS
list of each function
called
by
any
itself, e.g.
function
in object which
in
object
is
other
not
than
clumpget[fOOFNSjENTRYFNS].
16----------------------------------------------------------------------------Note that if .2.!Uect is the name of a function and universe is NIL,
LOCALFREEVARS will always be NIL, and GLOBALFREEVARS the same as fREEVARS.
It is only in connection with collections of functions that LOCAlFREEVARS
and GLOBALFREEVARS become interesting.
20.19
SELFRECURSIVE
list of function$ in
ob~ect
which call themselves
directly.
CAUSESELFCALL
list of
functions
in
object which
could
call
cause
some
themselves, perhaps indirectly.
CAUSERECURSION
list of
functions
in
object which
function to call itself, perhaps indirectly.
list of variables that are changed by object.
CHANGEVARS
where 'changed' means anu flavor of ass ignmen t,
i.e.
via SETO.
SETQO.
RPAO,
SETN,
or even
an
expression of the form (RPLACA (QUOTE atom) value)
(or FRPLACA, IRPLACA, SAVESET, etc.)17
CHANGERS
list of functions that change object.
Note: 'set' in English input means anu Ilauor 01 assignment, and translates the
same as 'change'.
SMASHVARS
list of variables whose
value
are
smashed
by
object, where 'smash' means the variable appears
as the
first argument
to one of the
functions on smasherslst. 18
list of
17----------------------------------------------------------------------------c Il1!!!p~ wi 11 accept as rEtlations SETOVARS, SETQERS, SETVARS, SETTERS,
SETQQERS, SETQQVARS, etc., in case the user wants to distingUish between
the various flavors of assi!Jnments. In English. "WHAT ARE THE SETQERS OF
X1", etc.
18
(RPLACA RPLACD FRPLACA FRPLACD IRPLACA IRPLACD NCONC NCONCl
ATTACH IATTJ\CH RPLNODE IRPLNODE RPLNODE2 IRPLNODE2). As
with assignments, clumpgct will accept as relations RPLACAERS, RPLACAVARS,
RPLACOERS. RPLACDVARS. etc., in case the user wants to distinguish the
different types of smashing.
Initially
INCONC
INCONCI
20.20
SMASHERS
list of functions that smash object.
TESTVARS
list of variables that are tested by object, where
'tested' means they appear as the first argument
to one of the list of functions on testerslst,
initially (ATOM lISTP NUMBERP NlISTP STRINGP EQ
EQP EQUAL NUll). or anywhere in an AND or OR, or
as the predicate in a COND clausei or as the first
argument to SELECTQ. etc.
TESTERS
list of functions that test object.
USEVARS
list of variables that are used in object, where
'used' means actually appear in the body of the
function, i.e. if a variable is simply bound, but
not
actually
used
anywhere,
it
included in the value of USEVARS.
TESTVARS are subsets of USEVARS.
USERS
list of functions that use object.
20.21
will
not
be
CHANGEVARS and
Index for Section 20
Page
Numbers
ALLCALLS[ FN: TREELST] ....••.•.••.•..•.•••••••..•.
CALLS[FN;EXPRFLG;VARSFLG] .......••••••••.••••.••
CLISP
.............................••••.•....•••.
CLUMPGET[OBJECT;RELATION;UNIVERSE]
dobugging
.•.••..•••••••
...................................... .
OONELST (printstructure variable/parameter)
OWIMIFY[X;L]
.......•.•...••.....•••••••••••• " •••
EXPR (property name) ............•..•..•..••..•••
EXPRFLG (printstructure variable/parameter)
FIRSTfN[FN]
...............•...•..•.
4
••••••••••••
FREEVARS[FN;EXPRFLG1 .........•.••..•..••.••.•.•.
INTERSCOPE ......................•.......•.•.•..•
IS NOT DEFINED (typed by PRINTSTRUCTURE) .•.••••.
LAST-PRINTSTRUCTURE
(printstructure variable/parameter) ....•.•.
LASTFN[FN] ......................•.•....••.•.••.•
LOOKA-T[ X]
••••••••••••••••••••••••••
6
••••••••••••
NIL: .........................................••.
NOFNS (printstructure variable/parameter) .•.•.••
NOTRACEFNS (printstructure variable/parameter)
P.P.E. (typed by PRINTSTRUCTURE) .........••....•
PATHS[X;Y;TYPE;MUST;AVOID;ONLY] ........•...•..•.
PROEPTH (printstructure variable/parameter)
PRINTSTRUCTURE[X;EXPRFLG;FILE] ...........••..•.•
QUOTEFNS (printstructure variable/parameter)
TENE X
.........•••..•.•.•..••.•••••••••••••••••••
TREELST (printstructure variable/parameter)
TREEPATHS[X;Y:TYPE;MUST;AVOID;ONLY] .....•••.••••
TREEPRINT[X;N] ...........••.......•••••.••.•••••
VARPRINT[DONELST;TREELST] .........•.....••.••••.
VARS[FN;EXPRFLG] ............••..•..•...•••••••••
YESFNS (printstructure variable/parameter) ••• ~ •.
*** (in interscope output) ....•..•••••••••••••••
-*CUTOFF** (typed by PRINTSTRUCTURE) ••••••••••••
INIlEX.20.1
20.9
20.10
20.5
20.17
20.5
-20.8
20.5
20.7
20.6,9
20.4,9
20.10
20.11-21
20.5
20.6,8-9
20.4,9
20.13,17
20.6
20.3
20.4
20.5,8
20.14-15
20.4
20.1-10
20.4
20.6
20.8
20.16
20.9
20.9
20.10
20.3
20.15
20.4
SECTION 21
"ISCELLANEOUS
21.1
Measuring Functions
time[timex;timen;timetyp]
is
an
nlambda
function.
It
executes
the
computatiQn timex, and prints out the number of
. conses and computation time.
Garbage collection
time 1s subtracted out.
(QUOTE PRETTY) (QUOTE PROP]
FILE CREATED 7-HAY-71 12:47:14
~TIHE«LOAD
GC: 8
582, 10291 FREE WORDS
PRETTYFNS
PRETTYVARS
3727 CONSES
10.655 SECONDS
PRETTY
If timen is greater than 1 (timen=NIL equivalent
to timen=1), time executes timex timen number of
times and prints out number of conses/timen, and
computation time/timen.
This is useful for more
accurate measurement on small computations,e.g.
(QUOTE (A B C») 10)
30/10 = 3 CONSES
.055/10 = .0055 SECONDS
(A 8 C)
~TIHE«COPY
21.1
If
~timetype
is 0, time measures and prints total
real time as well as computation time, e.g.
(QUOTE PRETTY) (QUOTE PROP»
FILE CREATED 7-MAY-71 12:47:14
~TIME«LOAD
1 0]
CiC: 8
!j8Z, 10291 FREE WORDS
PRETTYFNS
PRETTYVARS
~~7Z7 CONSES
:ll . 193 SECONDS
27.378 SECONDS, REAL TIME
PRETTY
If ,timetyp • 3, time measures and prints garbage
collection time as well as computation time, e.g.
(QUOTE PRETTY) (QUOTE PROP»
FILE CREATED 7-MAY-71 12:47:14
~TIME«LOAD
1 3]
(iC: 8
582, 1091 FREE WORDS
PRETTYFNS
I)RETTYVARS
:~ 7Z 7 CONSES
:lO.597 SECONDS
1.487 SECONDS, GARBAGE COLLECTION TIME
IJRETTY
Ano1~her
mea~.ures
option is timetype=T, in which case time
and prints the number of pagefaul ts.
The value of
time
is
the
value
of
the
last
evaluation of timex.
date[ac3]
If !!c3=NIL, obtains date and time from TENEX and
returns it as single string in format -dd-mm-yy
hh:aw:ss-, where dd is day, mm is month, yy year,
hh
hours,
mm
minutes,
-14-MAY-71 14:26:08-.
21.2
55
seconds,
e. g. ,
Other values of ac3 can be used to specify other
formats, e.g.
day of week, time zone, etce as
described in TENEX JSYS Manual.
clock[n]
for !!.=O
current value of the time of day clock
i.e., number of milliseconds since last
system start up.
for !!.=1
value of the time of day clock when the
user started up this INTERLISP.
1.e.,
difference between clock[O] and clock[l]
is number of milliseconds (real time)
since this INTERLISP was started.
for !!=2
number of milliseconds of compute time
since user started up this
INTERLISP
(garbage collection time 1s subtracted
ofr) .
for !!=3
number of milliseconds of compute time
spent
in
garbage
collections
(all
types).l
dismiss[n]
dismisses program for!!. milliseconds, during which
time program is in a state similar to an 1/0 wait,
i . e • , it uses no CPU time.
control-D, control-E, or
21.3
Can be aborted by
control~B.
conscount[n]
conscount[] returns the number of conses since
IN1'ERLISP started up.
If!l is not NIL, resets
conscount to !!.
boxcount[type;n]
number of boxing operations (see Section 13) since
INl'ERLISP started up.
If
~=NIL,
returns number
of large integer boxes;
type-FLOATING, returns
number of floating boxes. 2 If!l is not NIL,
resets the corresponding counter to !l.
gctrp[ ]
number of conses to next GC: 8, i. e ., number of
list words not in use.
Note that an intervening
GC of another type could collect as well
allocate additional list words.
as
See Section 3.
gctrp[n] can be used to cause an interrupt when
value of gctrp[]-n, see Section 10.
pagefaults[]
number of page faults since INTERLISP started up.
logout[ ]
returns to TENEX. a A subsequent CONTINUE command
will enter the INTERLISP program, return NIL as
the value of the call to logout, and continue the
computation exactly as if nothing had happened,
i.e., logout is a programmable control-C.
As with
control-C, a REENTER convnand following a logout
will reenter INTERLISP at the top level.
2--------~-----------~----------------------------------~----------------~-----
These counters are directly accessible via the COREVAL$ IBOXCN and FBOXCN.
8
If INTERLISP was started a~t a subsidiary fork (see subsys, page 21.18),
is returned to the higher fork.
con~rol
21.4
logout[] will not affect the state of &ny open
files.
21.2
Breakdown 4
Time gives analyses by computation
0
Breakdown is available
to
analyze the
breakdown of computation time (or any other measureable quantity) function by
function.
The user calls breakdown g.iving it a list of functions of interest.
These functions are modified so that they keep track of the "charge" assessed
to them.
The function results gives the analysis of the statistic requested as
well as the number of calls to each function. Sample output is shown' below. 6
SUB PRINT COMMENT!)
(SUPERPRINT SUBPRINT COMMENT1)
~.PRETTYOEF( (SUBPRINT) FOO)
(SUBPRINT)
... RESULTS()
FUNCTIONS
TIME
I CALLS
SUPERPRINT
25.294
458
SUBPRINT
32.96
169
COMMENTl
7.833
12
TOTAL
66.087
639
NIL
~BREAKDOWN(SUPERPRINT
The procedure used for measuring1s such that if one function calls other and
both are 'broken down'. then the time (or whatever quantity is being measured)
spent in the inner function is not charged to the outer function as well. 6
4-----------------------------------------------------------------------------breakdown was written by W. Teitelman.
6
This is with an interpreted prettyprint.
6
breakdown will not give accurate results if a function being measured 1s
not returned from normally, e.g. a lower retfrom (or error) bypasses it.
In this case, all of the time (or whatever quantity isbeing measured)
between the time that function is entered and the time the next function
being measured is entered will be charged to the first function.
21.5
To remove functions from those being monitored, simply unbreak the functions,
thereby
restoring
them
to
their original
breakdown on the new functions.
functions not on the new list.
state.
To
add
functions,
call
This will not reset the counters for any
IHowever breakdown[] can be used for zeroing
th~
counters of all functions being monitored.
To use breakdown for some other' statistic, before callin'g breakdown, set the
variable brkdwntype to the qU8:,ntity of interest, e.g.,
TIME,
CONSES,
etc.
Whenever breakdown is called with brkdwntype not NIL, breakdown performs the
necessary changes to its internal state to conform to the new analysis.
particular,
In
if this is the fir'st time an analysis is being run with this
statistic, the compiler may be called to compile the measuring function.? When
breakdown is through ini tializil1lg, it sets brkdwntype back to NIL. Subsequent
calls to breakdown will measure the new statistic until brkdwntype is again set
and a new breakdown performed.
~SET(BRKOWNTYPE
CONSES
Sample output is shown below:
CONSES)
CONSTRUCT)
(MATCH CONSTRUCT)
~FLIP«A BCD E F G H C Z) ( •• S1
(A B 0 E F G H Z)
~BREAKOOWN(MATCH
12 •• ) ( •• 13 •• »
~RESULTS()
FUNCTIONS
HATCH
CONSTRUCT
TOTAL
NIL
The
value
of brkdwntype
CONSES
32
47
79
is uSied
1 CALLS
1
1
2
to search
the
information necessary to analY2:e this statistic.
list brkdwntypes
for
the
The entry on brkdwntypes
corresponding to brkdwntype should be of the form (type form function), where
form computes the statistic, and function (optional) converts the value of form
to some more interesting quantity, e.g.
7------~-~----------------------··-------------------------------------~-------The measuring functions for TIME and CONSES have already been compiled~
21.6
(TIME (CLOCK 2) (LAMBDA (X) (FQUOTIENT X 1000»)8 measures computation time and
reports the result in seconds instead of milliseconds.
defined on brkdwntypes, an error is generated.
If brkdwntype is not
brkdwntypes currently contains
entries ,for TIME, CONSES, PAGEFAULTS, BOXES, and FBOXES.
More Accurate Measurement
Occasionally, a function being analysed is sufficiently fast that the overhead
involved in measuring it obscures the actual time spent in the function.
If
the user were using time, he would specify a value for timen greater than 1 to
give greater accuracy.
A similar option is available for breakdown.
The user
can specify that a function(s) be executed a multiple number of times for each
measurement, and
~he
average value reported, by including a number in the list
of functions given to breakdown, e.g., BREAKDOWN(EDITCOM EDIT4F 10 EDIT4E EQP)
means normal breakdown for editcom and edit4f but executes (the body of) edit4e
and
~
10 times each time they are called.
Of course, the functions so
measured must not cause any harmful side effects, since they are executed more
than once for each call.
The printout from results will look the same as
though each function were run only once, except that the measurement will be
more accurate.
8-~~-----~----~--------------------------------------- -------------------------
for more accurate measurement. the form for TIME 1s not (CLOCK Z) but
(ASSEMBLE NIL (HOVEl 1 • -5) (JSYS 13) (SUB 1 , GCTIM».
21.7
21.3
Edita 9
Edi ta is an editor for arrays.
However , its most frequent application is in
edi ting compiled functions (whi'ch are also arrays in INTERLISP). and a great
deal of effort in implementing !ldi ta, and most of its special features, are in
this area.
For example, edita knows the format and conventions of INTERLISP
compiled code, and so, in addition to decoding instructions a la DDT,10 edita
can
fill
in the appropriate C:OREVALS,
symbolic names for
references to literals, linked function calls, etc.
a
index registers,
The following output shows
sequence of instructions in a compiled function first as they would be
printed by DDT, and second by edita.
466716/
466717/
466720/
466721/
4667221
4667231
466724/
466725/
466726/
466727/
466730/
4667311
4667321
4667331
466734/
466735/
4667361
466737/
466740/
466741/
4667421
466743/
PUSH 16,LISP&KNIL
PUSH 16,LISP&KNIL
HRRZ 1,-12(16)
CAME l,LISP&KNIL
JRST 466724
HRRZ 1,@467575
PUSH 16,1
LISP&IOFIL,,467576
-3,,-3
HRRZ 1,-14(16)
CAMN 1,467601
JRST 466734
CAME 1,467602
JRST 466740
PUSH 16,467603
PUSH 16,467604
LISP&FILEN,,467605
JRST 467561
CAME 1,467606
JRST 466754
HRRZ 1,@-12(16)
PUSH 16,1
PUSH PP,KNIL
PUSH PP,KNIL
HRRZ 1,-10(PP)
51
61
CAME l,KNIL
.11
JRST 9
71
HRRZ 1,@'BRKFILE
81
PUSH PP,l
91
101 PBINo 'BRKZ
111 '!"524291
121 HRRZ 1,-12(PP)
13/ CAMN I, 'OK
141 JRST 17
151 CAME I, 'STOP
161 JRST 21
171 PUSH PP,'BREAKI
18/ PUSH PP,'(ERRORI)
191 CCALL 2,'RETEVAL
201 JRST 422
211 CAME 1,'GO
22/ JRST 33
23/ HRRZ l,@-10(PP)
241 PUSH PP,l
3/
4/
i---------------------~-------------------------------------------------------edita was written byW. Teitelman.
10
DDT is one of the oldest debugging systems still around.
For users
unfamiliar with it, let us simply say that edita was patterned after it
because so many people are feLJDiliar with it. - -
11
Note that edi ta prints the addresses of cells contained in the function
relative to the origin of the, function.
21.8
Therefore, rather than presenting !Q!!! as an array editor with some extensions
for editing compiled code, we prefer to consider it as a facility for editing
compiled code, and point out that it can also be used for editing arbitrary
arrays.
Overview
To the user, edita looks very much like DDT with INTERLISP extensions. It is a
function of one argument, the name of the function to be edited. 12 Individual
registers or cells in the function may be examined by typing their address
followed by a slash,13 e.g.
6/
HRRZ 1,-10(PP)
The slash is really a command to edita to open the indicated register. 14 Only
one register at a time can be open, and onlu open registers can be changed. To
change the contents of a register, the user first opens it, types the new
contents, and then closes the register with a carriage-return,16 e.g.
7/
CAMEt,"
CAMN 1,",)
13
Underlined characters were typed by the user. edi ta uses its own read
program, so that it is unnecessary to type a space before the slash or to
type a carriage return after the slash.
14
edt ta also converts absolute' addresses of cells within the function to
relative address on input. Thus, if the definition of foo begin~ at 85660,
typing 6/ is exactlu the same as typing 85666/.
---
15
Since carriage-return has a special meaning, edita indicates the balancing
of parentheses by typing a space.
21.9
If the user closes a register without specifying the new contents, the contents
are left unchanged.
Similarly. if an error occurs or the user types control-E,
the open register, if any, is closed without being changed.
Input Protocol
Edita processes all inputs not recognized as commands in the same way.
If the
input is the name of an instruction (i.e. an atom with a numeric OPD property),
the corresponding number is added to the input value being assembled, 16 and a
flag is set which specifies that
th~
input context is that of an instruction.
The general form of a machine instruction is (opcode ac , @ address (index»
described in Section 18.
as
TherftJfore, in instruction context, edita evaluates
all atoms (i f the atom has a COREVAL property, the value of the COREVAL is
-
used), and then if the atom corresponds to an ac,17 shifts it left 23 bits and
\
adds it to the input value, otherwise adds it directly to the input value, but
performs the arithmetic in the low 18 bits. 18 Lists are interpreted as
specifying index registers, and the value of f.!!: of the list (again COREVALs
are permitted) is shifted left
j,8
bits.
Examples:
16------------------------------'----------------------------------------------The input value is initially o.
17
i.e. if a " I has not been seen, and the value of the atom is less than 16,
the low 18 bits of the input value are all zero.
and
18
If the absolute value of 'the atom is greater than 1000000Q, full word
ari thmetic is used. For e:lCample. the indirect, bit is handled by simply
binding @ to 20000000Q.
21.10
PUSH
HRRZ
CAME
JRST
PP, KNIL
1,-10(PP)
1, 'GO
33 ORG 19
The user can also specify the address of a literal via the • command, see page
21.14.
For
example,
if
the' literal
• UNBROKEN"
is
in
cell
85672,
HRRZ 1,'· UNBROKEN" is equivalent to HRRZ 1, 85672.
When the input context is not that of an instruction, i.e. no OPO has been
seen, all inputs are evaluated (the value of an atom with a COREVAl property is
the COREVAL.) Then numeric values are simply added to the previous input value;
non-numeric values become the input value. 20
The only exception to the entire procedure occurs when a register is open that
is in the pointer region of the function, i.e. literal table.
atomic inputs are not evaluated.
In this case,
For example, the user can change the literal
FOO to fIE by simply opening that register and then typing fIE followed by
carriage-return, e.g.
FOO
Note that this is equivalent to 'FOOl
fOO
(QUOTE FIE»)
19----------------------------------------------------------------------------edi ta cannot in general know whether an address field in an instruction
that is typed in is relative or absolute. Therefore, the user must add
ORG, the origin of the function, to the address field himself. Note that
edita would print this instruction, JRST 53 ORG, as JRST 53.
20
Presumably there is only one input in this case.
21.11
Edita Commands and Variables
~
(carriage-return)
If a register is open and an input was t~¥ed,
store the input in the register and close it.
If a register is open and nothing was typed, close
the register without changing it.
If a register is not open and input was typed,
type its value.
ORG
Has the value of the address of the first
instruction in the function. i.e. loc of getd of
the function.
I
Opens the register specified by the low ,18 bits of
the quantity to the left of the /, and types its
contents. If nothing has been typed, it uses the
last thing typed by edita, e.g.
351
JRST 53
L
CAME 1, 'RETURN
If a register was open,
changing its contents.
/
L
closes
RETURN
it without
After a / command, edita returns to that state of
no input having been typed.
tab (control-I)
Same as carriage-return, followed by the address
of the quantity to the left of the t'ab, e.g.
351
53/
JRST 53 tab
CAME 1,' RETURN
Note that if a register was openl and input was typed, tab will change the open
register before closing it, e.g.
351
541
351
(period)
JRST 53
JRST 70
JRST 54
JRST 54 tab
1.
has the value of the address of the current (last)
register examined.
2i----------------------------------------------------------------------------If the register is in the unboxed region of the function, the unboxed value
is stored in the register.
21.12
line-feed
same as carriage-return followed by (ADD1 .)1 i.e.
closes any open register and opens the next
register.
t
same as'carriage-return followed by (SUB1 .)1
SQ (alt-modeQ)
has as its value the last quantity typed by edita
e.g.
351
.1
JRST 53
JRST 54
~
LITS
has as value the (relative) address of the first
literal.
BOXED
same as LITS
$ (dollar)
has as value the relative address of the
literal in the function.
=
Sets radix to -8 and types the quantity to the
left of the = sign, i. e. if anyth ing has been
typed, types the input value, otherwise, types SQ,
e.g.
351
JRST 54
last
!254000241541Q JRST 54=254000000066Q
Following =, radix is restored and edita returns
to the no input state.
OK
leave edita
?
return to I no input ' state.
? is a 'weak'
control-E, i.e. it negates any input typed, but
does not close any registers.
addressl, address21
prints22 the contents of registers address 1
through address2. . is set to address2 after the
completion.
22----------------------------------------------------------------------------output goes to file. initially set to T. The user can also set file (while
in edita) to the-nime of a disc file to redirect the output. (The user is
responsible for opening and closing file.) Note that file only affects
output for the addressl, address21 command.
--
21.13
IX
corresponds to the I in LAP. The next expression
is read, and if it is a small number, the
appropriate offset is added to it. Otherwise, the
literal table is searched for x, and the value of
IX is the (absolute) address -of that cell.
An
err'or is generated if the literal is not found,
i.e. I cannot be used to create literals.
:atom
defines atom to an address
(1) the value of SQ if a register is open,
(2) the input if any input was typed,
otherwise
(3) the value of ,.,.28
For example:'
JRST 54
: FOO)
:FIE.>
FIEI JRST FOO ..:.!:35
351
Edi ta keeps its symbol' tables on two free variables, usersyms and !mIst.
Usersyms is a li·st of elements. of the form (name • value) and is used for
encoding
input.
i.e.,
all
variables
on
usersyms
are
bound
to
corresponding values during evaluation of any expression inside edita.
their
Symlst
is a list of elements of the form (value • name) and is used for decodi ng
addresses.
Usersyms is initially NIL, while symlst is set to a list of all the
corevals.
Since the : command jildds the appropriate information to both these
two lists, new definitions will remain in effect even if the user exits from
edita and then reenters it later.
Note that the user can effectiv1sly define symbols without using the
command
by appropriately binding usersym.! andlor symlst before calling edita.
Also, he
can thus use different symbol tables for different applications.
SW (alt-modeW)
search command.
Searching consists of comparing the object of the search with the contents of
each register, and printing thosa that match, e.g.
23---------~-~------------------··--------------------------------------~-------
Only the low 18 bits are used and converted to a relative address whenever
possible.
21.14
HRRZ @ SW,.>
HRRZ 1,@'BRKFILE
23/ HRRZ 1,@-10(PP)
281 HRRZ 1,@-lZ(PP)
81
The SW command can be used to search either the unboxed portion of a function,
i.e. instructions, or the pointer region, i.e. literals, depending on whether
or not the object of the search is a number.
If any input was typed before the
SW. it will be the object of the search, otherwise the next expression is read
and used as the object. 24 The user can specify a starting point for the search
by typing an address followed by a 't' before calling SW, e.g. 1, JRST SW. If
no starting point is specified, the search will begin at 0 if the object is a
number, otherwise at LITS, the address of the first literal. 26 After the search
is completed,
, .,
is set to the address of the last register that matched .
If the search is operating in the unboxed portion of the function, only those
fields (i.e. instruction, ac, indirect, index. and address) of the object that
contain one bits are compared. 26 For example, HRRZ @ SW will find all instances
of HRRZ indirect, regardless of ac, index, and address fields.
Similarly,
'PRINT SW will find all instructions that reference the literal PRINT. 21
24----------------------------------------------------------------------------Note that inputs typed before the SW will have been processed according to
the input protocol, i.o. evaluated; inputs typed after the SW will not.
Therefore, the latter form 1s usually used to specify searching the
literals, e.g. SW FOO is equivalent to (QUOTE FOO) SW.
26
Thus the only way the user can search the pOinter region for a number is to
specify the starting point via '.'.
26
Alternately. the user can specify his own mask by setting the variable mask
(while in edita), to the appropriate bit pattern.
27
The user may need to establish instruction context for input without giving
a specific instruction. For example, suppose the user wants to find all
instructions with ac=1 and index=PP. In this case, the user can give & as
a pseudO-instruction, e.g. type & I, (PP).
21.15
If the search is operating in the pointer region, a 'match' is as defined in
the editor.
For example, SW (8.:) will find all registers that contain a list
consisting of a single expression.
SC (alt-modee)
like SW except only prints the first match, then
prints the number· of matches when the search
finishes.
Editing Arrays
Edita is called to edit a fun(:tion by giving it the name of the function.
Edita can also be called to edit an array by giving it the array as its (irst
argument,28 in which case the following differences are to be not~d:
1.
decoding - The contents of registers in the unboxed region are boxed
and
printed
as
numb4!rS,
i. e.
they
are
never
interpreted
as
instructions, as when editing a function.
2.
addressing convention - Whereas 0 corresponds to the first instruction
of a function, the first element of an array by convention is element
number 1.
3.
input protocols - If a register is open, lists are evaluated, atoms
are not evaluated (except for SO which is always evaluated).
If no
register is open, all inputs are evaluated, and if the value is a
number, it is added to the 'input value'.
4.
left half - If the left half of an element in the pointer region of an
array is not all 0'5 or NIL, it is printed followed by a
21.16
;~
e.g.
101
(A B)
T
Similarly, if a register is closed, either its left half, right half,
or both halves can be changed, depending on the presence or absence,
and position of the ; e.g.
changes left
~
101
(A B) ; T
.:l..
B
T
NIL~
.:l..
B
NIL
A
.:l..
A
changes right
C')
., C
changes both
If ; is used in the unboxed portion of an array, an error will be
generated.
The SW command will look at both halves of elements in the pointer region, and
match if either half matches.
Note that SW A ; B is not allowed.
This ends the section on edita.
21.4
Interfork Communication
The functions described below permit two forks (one or both of them INTERLISP)
to have a common area of address space for communication by providing a means
of
assigning
a
block of
storage guaranteed not
to moue
during
garbage
collectio'ns.
getblk[n]
Creates a block !!. pages in size (512 words per
page).
Value is the address of the first word in
the block, which is a multiple of 512 s1.nee the
block will always begin at a page boundary.
not enough
pages are available,
error ILLEGAL OR IMPOSSIBLE BLOCK.
21.17
generates
If
the
Note, the block can be used for storing unboxed numbers onlu.
To store a number in the block, the following function could be used:
[SETBLOCK (LAMBDA (START N X) (CLOSER (IPLUS (LOC START) N) X]
Some boxing and unboxing can be avoided by making this function
~ompile
open
via a substitution macro.
Note, getbllt. should be usedspaT'ingll/ since selleral unmollable regions 01 memorll
ca,n make it difficult or impossible Jor the garbage collector to lind a
contiguous region large enough for expanding arrag space.
relblk[addressin]
releases a block of storage beginning at address
and extending
for !
Causes
pages.
an
error
ILLEGAL OR IMPOSSIBLE BLOCK if any of the range 1s
not a block.
21 .5
Value is address.
SUbsYS29
This section describes a funct:Lon, subsys, which permits the user to run a
TENEX subsystem, such as SNDMSG, SRCCOM, TECO, or even another INTERLISP, from
inside
of
an
INTERLISP without
destroying
the
latter.
In
particular,
SUBSYS(EXEC) will start up a luwer exec, which will print the TENEX herald,
followed by @.
The user can then
d~
anything at this exec level that he can at
the top level, without affecting his superior INTERLISP.
For example, he can
start another INTERLISP. perfonlD a sysin, run for a while. type a control-C
returning him to the lower exec, RESET, do a SNDMSG, etc.
The user exits from
the lower exec via the command QILlIT, which will return control to subsys in the
21.18
higher INTERLISP.
Thus with subsys. the user need not perform a sysout to save·
the state of his INTERLISP in order to use a TENEX capability which would
otherwise clobber the core image.
Similarly. subsys provides a way of checking
out a sysout file in a fresh INTERLISP without having to commandeer another
teletype or detach a job.
While subsys can be used to run any TENEX subsystem directly, without gOing
through an intervening exec, this procedure is not recommended.
The problem is
that control-C always returns control to the next highest exec.
Thus if the
user is running an INTERLISP in which he performs SUBSYS(LISP), and then types
control-C to the lower INTERLISP, control will be returned to the exec above
the first INTERLISP.
The natural REENTER command would then clear the lower
INTERLISP,30 but any files opened by it would remain open (until the next
@RESET) •
I f the user elects to call a subsystem directly, he must therefore
know how it is normally exited and always exit from it that way.81
Starting a lower exec does not have this disadvantage, since it can onlu be
exited via QUIT,
i.e.,
the lower exec is effectively 'errorset protected'
against control-C.
subsys[file/forkjincomfile;outcomfilejentrypointflg]
If
file/fork=EXEC.
otherwise
runs
starts
up
lower
1)
n (n
move forward n events, 1.e. in direction of
inl:reasing event number.
If given as the first
'cc)lMland,' !1 specifies the event with event number
n.
n (n
.s
... atom
-1)
move backward -n events.
search backward for an event whose Junction
matches atom (i.e. for ~ format only), e.g.
whe!reas FIE would refer to event
FIE would
refer to event 44. Similarly, EOS would specify
event 51, whereas .. EOS event 48.
17, ..
search backward for an event whose input contains
an expression that matches pat as described in
Section 9.
...
I
next search is to go forward instead of backward,
(if given as the first •command', next search
begins with last, i.e. oldest, event on history
1is t), e. g. .. LAMBDA refers to event 38;
HAKEFIlES .. RECOMPILE refers to event 51.
F
next object is to be searched for, regardless of
what it is, e.g.
F -2 looks for an event
containing a -2.
=
next search
is to
look at uaLues,
instead
of
8---~:;~-~~~~~=~~~;~-----------------------·----------------------------------9
i.e. anything else except for .. , -,
described above.
22.12
and
which are, interpreted as
inputs, e.g. =UNDO refers to event 49; 45 = FIE
refers to event 43; ~ = LAMBDA refers to event 37.
specifies the event last located.
Note: each search skips the current event, i.e. each command always moves the
cursor.
For example, if FOO refers to event !l. Foo FIE will refer to some
event before event !l, even if there is a FIE in event !l.
An event specification specifies. one or more events:
FROM #1 THRU 12
sequence of events from the
wi th address (11 through event wi th address
'2,
e.g. FROM GETD THRU 49 specifies events 47,
48, and 49. 11 can be more recent than 12, e.g.
FROM 49 THRU GETP specifies events 49, 48, and 47
(note reversal of order).
FROM 11 TO 12
11 TO 12
Same as THRU but does not include event 12.
FROM 11
Same as FROM 11 THRU -1, e.g. FROM 49 specifies
events 49, 50, 51, and 52.
THRU 12
Same as FROM -1 THRU '2, e.g. THRU 49 specifies
even ts 52, 51, 50, and 49.
Note reversal of
order.
TO
Same as FROM -1 TO '2.
#1 AND 12 AND ..• AND In
i. e. a sequence of event addresses separated by
AND's,.e.g. FROM 47 TO LOGOUT would be equivalent
to 47 AND 48 AND MAKEFILES.
empty
i.e. nothing specified, same as -1, unless 1ast
event was an UNDO, in which case same as -2. 11
11 THRU 12
the
eve2h
10----------------------------------------------------------------------------i.e. the symbol #1 corresponds to all words between FROM and THRU in the
event specification, and #2 to all words from THRU to the end of the event
specification. for example, in FROM Foo 2 THRU FIE -1, 11 is (FOO 2), and
12 is (FIE -1).
11
For example, if the user types (NCONC Foo FIE), he can then type UNDO,
followed by USE NCONC1.
22.13
@ atom
refers to the events named by atom, via the NAME
conunand, page 22.25 e.g., if the user names a
pclrticular event or events FOO, @ FOOspecifies
those events.
@@ ~
~ is an event specification and interpreted as
above, but with respect to the archived history
list, as specified on page 22.27.
22.4
History Commands
All history cOl7D1land.s can be iTl'put a.s either lists, or a.s line.s (.see readltne
Section 14. and also page 22.47).
t is u.sed to denote an event .specification. Unle.ss specified otherwise,
omitted is the same as t z-l, e.g. REDO and REDO -1 are the same.
REDO
~
USE vars FOR args IN t
redoes the event or events specified by
REDO FROM -3 redoes the last three events.
SUbstitutes ill! for args in
re!'iult, e.g.
t.
If
t, e. g.
and redoes the
USE LOG ANTILOG FOR ANTILOG LOG IN -2 AND -1.
Substitution is done by esubst, Section 9, and is
carried out as described below.
USE vars 1 FOR args 1 AND •.. AND vars FOR args n IN t
Mor"e general form of USE command.
See description
of SUbstitution algorithm below.
Every USE command involves thr,ee pieces of information: the variables to be
substituted, the arguments to be substituted for, and an event specification,
which defines the expression (input) in which the substitution takes place. 12
If args are omitted, i.e. the form of the· command is USE vars IN
~,
or just USE
vars (which is equivalent to USE vars IN -1), and the ·event referred to was
itself a USE conunand, the argument's and expression substituted into are the
same as for the indicated USE cmnmand.
In effect, this USE command is thus a
i2------------------------------··---------------------------------------------The USE command is parsed by a small finite state parser to distinguish the
variables and arguments.
be parsed correctly.
Fo." example, USE FOR FOR AND AND AND FOR FOR will
22.14
continuation of the previous USE command.
For example, on page 22.7, when the
user types (LOG (ANTILOG 4», followed by USE 4.0 40 400 FOR 4, followed by
USE -40.0 -4.00007 -19., the latter command is equivalent to
USE -40.0 -4.00007 -19. FOR 4 IN -2.
If
args
are
omitted and
the event referred to was not
a
USE
command,
substitution is for the operator in that command, i.e. if a lispx input, the
name of the function, if an edit command, the name of the command.
For example
ARGLIST(FF) followed by USE CALLS is equivalent to USE CALLS FOR ARGLIST.
If
is omitted, but args are specified, the first member of args is used for
~, e.g. USE PUlO FOR @UlD is equivalent to USE PUlD FOR @UTD IN F @UTO. 13
If
~
the USE command has the same number of expressions as arguments,
sUbstitution
procedure
is
straightforward, 14
i.e.
the
USE X Y FOR U V means
substitute X for U and Y for V, and is equivalent to USE X FOR U AND Y FOR V.
However.
the
substituting
USE
command
several
also
permits
expressions
for
distributive
the
same
substitutions,
argument.
For
i.e.
example,
USE ABC FOR X means first substitute A for X then substitute B for X (in a
new copy of the expression), then substitute C for X.
as three separate USE commands.
equivalent
to
The effect is the same
Similarly, USE ABC FOR D AND X Y Z FOR W is
USE A FOR D AND X FOR W,
followed by USE B FOR 0 AND Y FOR W,
ia----------------------------------------------------------------------------The F is inserted to handle correctly the case where the first member of
is a number. e.g. USE 4.0 4.0 400 FOR 4. Obviously the user means find
the event containing a 4 and perform the indicated substitutions, whereas
USE 4.0 40 400 FOR 4 IN 4 would mean perform the substitutions in event
ar~
number 4.
14
Except when one of the arguments and one of the variables are the same,
e.g. USE X Y FOR Y X, or USE X FOR Y AND Y FOR X. This situation is noticed
when parsIng the command, and-handled correctly:
22.15
followed
by
USE C FOR 0 AND Z FOR W.
USE ABC FOR 0 AND X FOR y16
corresponds to three substitions, the first with A for 0 and X for Y,
also
the
second with B for 0, and X for Y, and the third with C for 0, and again X for
Y.
However.
error.
USE ABC FOR 0 AND X Y FOR Z is ambiguous and will cause an
Essentially, the USE cOltDmand operates by proceeding from left to right
handling each 'AND' separately.
Whenever the number of expressions exceeds the
number of expressions available~ the expressions multiply.16
FIX
~
puts the user in the editor looking at a copy of
th{1 input( s) for ~, Whenever the user exits via.
OK, the result is unread and reexecuted exactly as
with REDO.
FIX is provided for those cases when the modifications to the input(s) are not
of the type that can be specifie!d by USE, i.e. not substitutions.
~(OEFINEQ
For example:
FOO (LAMBDA (X) (FIXSPELL SPELlINGS2 X 70]
INCORRECT DEFINING FORM
FOO
.. FIX
EDIT
.p
(OEFINEQ FOO (LAMBDA & &»
• (LI 2)
OK
(FOO)
..
The user can also specify the edit command(s) to lispx, by typing - followed by
the command(s) after the event
~ipecirication,
e.g. FIX - (LI 2). In this case,
the editor will not type EDIT, or wait for an OK after executing the commands.
16
Thus USE ABC 0 FOR E F metans substitute A for E at the same time as
subs ti tuting B for F, then in another copy of the indicated expression,
substi tute C for E and 0 for F. Note that this is also equivalent to
USE A C FOR E AND 8 0 FOR F.
22.16
Implementation of REDO, USE, and FIX
The input portion of an event is' represented internally on the history list
simply as a linear 'sequence of the expressions which were read.
an input in
For example,
format is a list Consisting of two expressions, an an input
in eval format is a list of just one expression. 17 Thus if the user wishes to
~
convert an input 'in
~
format to eval format, he simply moves the function
name inside of the argument list:
(F/l (AND (EXPRP X) (PRINT Xl
~MAPC(FOOFNS
NIL
~EXPRP(F001)
T
MAPC
EDIT
-P
(MAPC (FOOFNS
-(BO 2)
-elI 1)
-P
«MAPC FOOFNS
~FIX
&»
&»
OK
FOOl
FIE2
FUM
NIL
...
By Simply converting the input from two expressions to one expression, the
desired effect, that of mapping down the list that was the value of foofns, was
achieved.
REDO,
USE,
and
FIX all
operate by obtaining
the
input
portion
of
the
corresponding event, processing the input (except for REDO), and then storing
17----------------------------------------------------------------------------For inputs in eval format, i.e. single expressions, FIX calls the editor so
that the current expression is that input, rather than the list consisting
of that input - see the example on the preceding page. However, the entire
list is actually being edited. Thus if the user typed t P in that example,
he would see «DEFINEQ Foo &».
22.17
it on the history list as thl9 input portion of a new event.
command completes operating by simply unreading the input.
subsequently
'reread.',
The history
When the input is
the evont which already contains the input will be
retrieved and used for recording the value of the operation, saving sideeffects, etc., instead of creating a new event.
Otherwise the input is treated
exactly the same as if it had been typed in directly.
If
~
specifies more than one event, the inputs for the
correspondin~
events are
simply concatenated into a linear sequence, with special markers representing
carriage returns 18 inserted between each input to indicate where new lines
start.
to by i.
inputs
The result of this concatenation is then treated as the input referred
For example, when the user typed REDO FROM F ([7] on page 22.3) the
for
the
corresponding
six
events
were
concatenated to produce
(F PUTO 10 (1 MOVD) 10 3 10 (Xnt 2) 10 0 10 (SW 2 3». Similarly,
if the user
had typed USE @UTO FOR PUTO IN 15 THRU 20, (F PUTO #0 (1 MOVO) 10 3 10 (XTR 2)
#0 0 10 (SW 2 3»
would have b'ten constructed, and then @UTO substituted for
PUTO throughout it.
The same convention is used for representing multiple inputs when a USE command
involves sequential SUbstitutions.
For example, if the user types GETO(FOO)
and then USE FIE ,FUM FOR FOO, the input sequence that will be constructed is·
(GETO (FIE) #0 GETO (FUM», whic:h is the result of substituting FIE for FOO in
(GE TO (FOO»
concatenated with the resul t
of subs ti tuting FUM for
FOO in
( GE TO (FOO».
Once such a multiple input is constructed, it is treated exactly the same as a
single input, i.e. the input sequence is recorded in a new event, and then
18----------------------------------------------------------------------------The value of (VAG 0) is currently used to represent a carriage return on
the grounds that it cannot be typed in by the user, and thus cannot cause
ambiguities.
22.18
unread, exactly as described above.
When the inputs are 'reread,' the 'pseudo-
carriage-returns'
lispxread
are
treated
by
and
readline
carriage returns, i.e. they serve to distinguish between
exactly
~
as
real
and eval formats
on inputs to lispx, and to delimit line commands to the editor.
Note that once
this multiple input has been entered as the input portion of a new event, that
event can be treated exactly the same as one resulting from type in.
In other
words, no special checks have to be made when referencing an event, to see if
it
is
simple
REDO FROM F,
or
([10]
multiple.
page
22.3)
Thus,
when
the
user
types
REDO does not even notice
retrieved from the previous event is(F PUlO 10
input, it simply records this input and unreads it.
(SW 2 3»
REDO
that
following
the
input
i.e. a multiple
Similarly. when the user
then types USE @UlO FOR PUlO on this multiple input, the USE command simply
carries out the substitution, and the result is the same as though the user had
typed USE @UlO FOR PUlO IN 15 lHRU 20.
In sum. this implementation permits
~
to refer to a single simple event, or to
several events, or to a single event originally constructed from several events
(which may themselves have been multiple input events, etc.) without having to
treat each case separately.
History Commands Applied to History Commands
Since history commands themselves do not appear in the input portion of events
(although they are stored elsewhere in the event), they do not interfere with
or affect the searching operations of event speCifications.
In effect, history
conunands are invisible to event specifications. 19 As a result, history conunands
themselves cannot be recovered for execution in the normal way.
For example,
19----------------------------------------------------------------------------With the exception described below under "History Commands that Fail".
22.19
if the user types USE ABC FOIl D and follows this with USE E FOR 0, he will
not produce the effect of USE ABC fOR E (but instead will simply cause E to
be
substituted for D in the
effect,
i.e.
USE ABC FOR E.
last event containing a 0).
To produce this
the user should type USE D FOR E IN USE.
The
appearance of the word REDO, USIE or FIX in an event address specifies a search
for the corresponding his toru c:onunand.
(for example, the user can also type
UNDO REDO.) It also specifies that the text of the history command itself be
treated as though it were the input. - However, the user must remember that the
context
historll.
in tllhich a histoTII command i.s
not
the
original
Icontext.
reexecuted is'that of the current
For
example,
if
the
user
types
USE FOO FOR FIE IN -1, and then later types REDO USE, the -1 will refer t'o the
event
before
the
REDO,
not
bofore the
USE.
Similarly,
if
the
user
types
REDO REDO followed by REDO REDO, he would cause an infinite loop, except for
the fact that a special check detects this type of situation.
History Commands that fail
The one exception to the statement that
'history commands are invisible to
event specifications' occurs whelll a history command fails to produce any input.
For example,
causing
lisp~
suppose the user types USE LOG FOR ANTILOG AND ANTILOG FOR lOGG,
to respond LOGG 7.
Since the USE command did not produce any
input, the user can repair it by typing USE LOG FOR LOGG (i.e. does not have ,to
specify IN USE).
This latter USE command will invoke a search for LOGG, which
will find the bad USE command.
Jispx then performs the indicated substitution,
and unreads USE lOG FOR ANTILOG AND ANTILOG FOR lOG. In turn, this USE command
invokes a search for ANTILOG, which, because it wa.s not tllped in but reread.
ignores the bad USE command which was found by the earlier search for LOGG, and
which is still on the history
to
li~it.
In other words, historll conunands that fail
produce input are visible to searches ari.sing from event .specification.s
typed in by the u.ser. but not to .secondarll event specification.s.
22.20
In addition, if the most recent event is a history conunand which failed to
produce input, a secondary event specification will effectively back up the
history
list
one
event
so
that
relative
event
specification will not count the bad history conunand.
user
types
numbers
for
that
event
For example, suppose the
USE lOG FOR ANTILOG AND ANTILOG FOR lOGG IN -2 AND -1,
and
after
lispx types lOGG 1, the user types USE lOG FOR lOGG. He thus causes the command
USE LOG FOR ANTILOG AND ANTILOG FOR lOG IN -2 AND -1
unread.
to
be
constructed
and
In the normal case, -1 would refer to the last event, i.e. the 'bad'
USE command, and -2 to the event before 1t.
However, in this case, -1 refers
to the event before the bad USE command, and the -2 to the event before that.
In short, the caveat that "the user must remember that the context in which a
h is tory conunand is reexe,cuted is that of the
~urrent
history. not the original
context" does not apply if the correction is performed immediately.
More History Conunands
RETRY t.
similar to REDO except sets helpclock so that any
errors' that occur while executing t. will cause
breaks.
... vars
similar to USE except substitutes for the (first)
operand.
For
example,
EXPRP(FOO)
followed
by ••• FIE FUM
is
equivalent
to
USE FIE FUM FOR Foo. See also event 52 on page 22.9.
17 t.
prints history list. If t.
the entire history list,
recent events.
Otherwise
events specified in t.
specified), e.g. 11 -1, 11
is omi tted, 77 prints
beginning with most
11 prints only those
(and in
the order
10 THRU 15, etc.
71 commands are not entered on the history list, and so do not affect relative
event numbers.
In other words, an event specification of -1 typed following a
17 command will refer to the event immediately preceding the 11 command.
22.21
11 will print the history command, if any, associated with each event as shown
at [9] on page 22.3 and page
Note that these history conunands are not
preceded by prompt characters, indicating they are not stored as input. 20
2~~.7.
11 prints multiple input events under one event number (see page 22.7).
Since events are initially stored on the history list with their value field
equal to bell (control-G), if an operation fails to complete for any reason,
e.g. causes an error, is aborted, etc., its 'value' will be bell.
This is the
explanation for the blank line in event 2, page 22.7, and event 50, page 22.9.
17 is implemented via the function printhistory, page 22.60, which can also be
called directly by the user.
*
UNDO
undoes the side effects of the specified events.
For each event undone, UNDO prints a message: e.g.
RPLACA UNDONE, REDO UNDONE etc.
If nothing is
undone because nothing was saved, UNDO types
NOTHING SAVED. If nothing was undone because the
event(s)
were
already
undone,
UNDO
types
ALREADY UNDONE. If t is empty, UNDO searches back
for the last event that contained side effects,
was not undone, and itself was not an UNDO
~
20----------------------------------------------------------------------------REDO, RETRY, USE, ... , and FIX commands, i.e. those commands that reexecute
previous events, are not stored as inputs, because the input portion for
these events are the expres.sions to be 'reread'. The history commands
UNDO, NAME RETRIEVE, BEFORE, and AFTER are recorded as inputs, and 11
prints them exactly as they were typed.
t
2Z.2Z
conunand.21 22
UNDO t.
For
EaCh. xi refers to a message printed by DWIM in the
event(s) specified by~. The side effects of the
corresponding DWIM corrections, and only those
side effects, are undone.
example,
if
the
message
PRINTT [IN FOO] -) PRINT
UNDO : PRINTT or UNDO: PRINT would undo the correction. 23
were
printed,
•
•
is a special form of the USE conunand for conveniently specifying character
$
substitutions.
In addition, it has a number of useful default options in
connection with events that involve errors.
:&
x FOR y
equivalent to USE
Ix$
FOR $y$
For example, the user types MOVD(FOO FOOSAVE T), he can then type S FIE FOR FOO
to
perform
MOVD(FIE FIESAVE T).
Note
that
USE FIE FOR FOO
would
perform
MOVD(FIE FOOSAVE T).
21----------------------------------------------------------------------------Note that the user can undo UNDO commands themselves by specifying the
corresponding event address, e.g.
22
UNDO -3 or UNDO
UNDO~
UNDOing events in· the reverse order from which they were executed is
guaranteed to restore all pointers correctly, e.g. to undo all effects of
last five events, perform UNDO THRU -5, not UNDO FROM -5. Undoing out of
order may have unforseen effects if the operations are dependent.
For
example,
if
the
user
performed
(NCONC1 FOO FIE),
followed
by
(NCONCI FOO FUM), and then undoes the (NCONC1 FOO FIE), he will also have
undone the (NCONC 1 FOO FUM). I f he then undoes the (NCONC 1 FOO FUM), he
will cause the FIE to reappear, by virtue of restoring FOO to its state
before the execution of (NCONCI FOO FUM).
For more details, see page
22.42.
23
Some portions of the messages printed by DWIM are strings, e.g. the message
FOO UNSAVED is printed by printing FOO and then " UNSAVED". Therefore, if
the user types UNDO : UNSAVED, the DWIM correction will not be found. He
should ins teadtype UNDO :FOO or UNDO : SUNSAVEDS (al t-modeUNSAVEDal tmode, see R command in editor. section 9).
ZZ.Z3
An abbreviated form of , is available:
$ y
x
'x FOR y,
sarne as
can
also
$ y -)
i.e. yls are changed to
be written
as
$
y TO x, $ Y = x,
or
x.
does event location the sarne as the USE command,
$
XiS.
i.e.
if IN -- is not
specified, it searches for l.24
After
$
..
finds the event, it llooks. to see if an error was involved in that
event,25 and if the indicated 4::haracter substitution can be performed in the
offender.
If so, , assumes the substitution refers to the offender, performs
the substitution, and then substitutes the result for the offender throughout.
For
example.
the
·user
types
U.S.A. FOOOVARS error message.
(PRETTYOEF FOOFNS IFOO FOOVARS)
causing
a
The user can now type S 00 0, which will change
FOOOVARS to FOOVARS. but not change FOOFNS or FOO.
If an error did occur in the specified event, the user can also omit specifying
in which case the offender is used.
~,
above
example
Thus, the user could have corrected the
by simply typing S FOOVARS.
8imilarly,
if
the
user
types
LOAD(PRSTRUC PROP), causing the error FILE NOT FOUND PRSTRUC, he can request
the file to be loaded from
esubst
is
used
(R PRSTRUC .
can
now type
protection.
in an
indefinite number of lines of input,
The user
under errorset
The input lines are saved and unread when the user exits the type-
ahead loop with the conunand SGO (alt-modeGO).
While in the type-ahead loop, 11
can be used to print the type·-ahead. FIX to edi t the type-ahead, and SQ to
erase the last input (may be used repeatedly).
22.28
For example:
"'TYPE-AHEAD
)SYSOUT(TEM)
)MAKEFILE(EDIT)
)BRECOMPILE«EDIT WEOIT»
)F
)$Q
\\F
)$Q
\\BRECOMPILE
)LOAD(WEDIT PROP)
)BRECOMPILE«EDIT WEOIT»
)F
)MAKEFILE(BREAK)
)LISTFILES(EDIT BREAK)
>SYSOUT(CURRENT)
>LOGOUT]
>11
)SYSOUT(TEM)
)MAKEFILE(EOIT)
)LOAD(WEOITPROP)
)BRECOMPILE«EDIT WEOIT»
)F
.
29
.
)MAKEFILE(BREAK)
)LISTFILES(EOIT BREAK)
)SYSOUT(CURRENT)
)LOGOUT]
)FIX
EDIT
*(R BRECOMPILE BCOMPL)
*p
«LOGOUT) (SYSOUT &) (LISTFILES &) (HAKEFILE &) (F) (BCOHPL &)
(LOAD &) (HAKEfIlE &) (SYSOUT&»
*(OElETE LOAD)
·OK
)SGO
The TYPE-AHEAD conunand may be aborted by SSTOP; control-E simply aborts the
current line of input.
29----------------------------------------------------------------------------Note that type-ahead can be addressed to the compiler, since it uses
lispxread for input. Type-ahead can also be directed to the editor, but
type-ahead to the editor and to .lispxcannot be intermixed.
22.29
SBUFS (alt-modeBUFS)
Whenever an error occurs 1n
*
*
*
is a command for recovering the input buffers.
e~:ecuting
a lispx input or edit command, or a
control-E or control-D 1s typed, the input buffers are saved and cleared.
The
SBUFS command is used to restore the input buffers, i.e. its effect is exactly
the same as though the user had retyped what was 'lost.' For example:
*(-2 (SETQ X (COND «NULL Z) (CONS
(user typed control-E)
*p
(COND
(& &) (T Be»
*2
*SBUFS
(-2 (SETQ X (COND «NULL Z) (CONS
and user can now finish typing the (-2 .. ) conunand.
Note:
the type-ahead does not have to have been seen by INTERLISP,
i.e.,
echoed, since the system buffer is also saved.
Input buffers are not saved on the history list, but on a free variable.
Thus,
only the contents of the input buffer as of the last clearbuf can ever be
recovered.
However, input buffers cleared at evalgt are saved independently
from those cleared by break or the editor.
The procedure followed when the
user types SBUFS is to recover first from the local buffer, otherwise from the
top level buffer. 30 Thus the user can lose input in the editor, go back to
evalgt. lose input there. then go back into the editor, recover the editor'S
30---------------------------------------------------------------------------The local buffer is stored on lispxbufs; the top level buffer on
to~l is~)U fs.
The forms of both buffers are (CONS (LINBUF) (SYSBUF» (see
Section 14). Recovery of a buffer is destructive, i.e. SBUFS sets the
corresponding variable to NIL. If the user types SBUFS when both lispxbufs
and toplispxbufs are NIL, the message NOTHING SAVED is typed, and an error
generated.
22.30
buffer, etc.
Furthermore, a buffer cleared at the top can be recovered in a
break, and vice versa.
*
*
The following four corrunands, DO, !F. !E, and !N, are only recognized in the
editor:
00 com
allows the user to supply the command name when it
was omitted. (USE is used when a command name is
incorrect).
For example, suppose the user wants to perform
(-2 (SETQ X (LIST Y Z»)
but
instead
types
just
(SETQ X (LIST Y Z».
The
editor will type SETQ 1, whereupon the user can type 00 -2. The effect is the
same as though the user had typed FIX, followed by (LI 1), (-1 -2). and OK,
i • e. the command (-2 (SETQ X (LIST Y Z») is executed.
00 also works if the
last command is a line command.
!F
same as 00 F.
In the case of IF, the previous command is always treated as though it were a
line command, e.g. if the user types (SETQ X &) and then !F, the effect is the
same as though he had typed F (SETQ X &), not (F (SETQ X &».
!E
same as DO E. Note !E works correctly
'commands' typed in eval or ~ format.
!N
same as 00 N.
22.31
for
•
control-U
•
when typed in at any point during an input being
read by lispxread, permits the user to edit the
input before it is returned to the calling
function.
This feature is useful for correcting mistakes noticed in typing be/ore the
input is executed, instead of waiting till after execution and then performing
an
UNDO
and
a
FIX.
For
example t
if
the
user
types
(OEFINEQ (FOO (lAMBDA (X) (FIXSPEll X and at that point notices the missing
left parenthesis, instead of cClmpleting the input and allowing the error to
occur, and then fixing the input, he can simply type control-U,31 finish typing
normally, whereupon the editor is called on (FOO (LAMBDA (X) (FIXSPElLX -- 1,
which the user can then repair, e.g. by typing ell 1).
If the user exits from
the edi tor via OK,
the (corrected) expression will be returned to whoever
called lispxread exactly as though it had been typed. 32 If the user exits via
STOP, the expression is returned so that it can be stored on the history list.
However it wi 11 not be executed.
In other words, the effect is the same as
though the user had typed control-E at exactly the right instant.
ai-----------------------------Control-U can be typed at clOy
q
point, even in the middle of an atom; it
simply sets an internal flag checked by lispxread.
--------------------- -------------------------
82
Control-U also works for calls to readline, i.e., for line commands.
22.32
*
*
*
is an nlambda function for obtaining the value 95
a
particular
event,
e.g. (VAlUEOF -1),
(VAlUEOF ~FOO -2).
valueof
The value of an event consisting of several
operations is a list of the values for each of the
individual operations.
Note:
the value field of a historll entrll is initialized to bell (control-G).
Thus a value oj bell indicates that the corresponding operation did not
complete. i.e. was aborted or caused an error (or else returned bell).
*-
prompt#flg
*
is a flag which when set to T causes the current
event number to be printed before each ~,: and *
prompt characters. See description of promptchar,
page 22.51.
promptlflg is initially NIL.
*
archivefn
allows the user to
automatically archived.
specify
events
to
be
When archivefn is set" to T, and an event is about to drop off the end of the
history list and be forgotten, archivefn is called giving it as its first
argumen~
the input portion of the event p and as its second argument, the entire
88----------------------------------------------------------------------------Al though the input for valueof is entered on the history list before
valueof is called, valueof[-l]
immediately before the valueof
history list up one entry
Similarly. (VAlUEOF FOO) will
contains a FOO.
still refers to the value of the expression
input, because valueof effectively backs the
when it retrieves the specified event.
find the first event before this one that
22.33
event. 34 If archivefn returns T, the event is archived.
users
like
to keep a record e)f all calls to load.
(LAMBDA (X Y) (EQ (CAR X) (QUOTE LOAD»)
archivefn
must
be
will
both set and defined.
some
Defining archivefn as:
accomplish
archivefn
For example,
is
this.
Note
initially
that
NIL
and
undefined.
•
lispxmacros
•
•
provides a macro facility for lispx.
lispxmacros allows the user to diefine his own lispx commands.
elements of the form (command def).
It is a list of
Whenever command appears as the first
expression on a line in a lispx input, the variable lispxline is bound to the
rest
of
the
evaluated.
line,
the event :l.s recorded on the history list,
and def
is
Similarly. whenever command appears as car of a form in a lispx
input. the variable lispxline is bound to cdr of the form, the event recorded,
and
def
is evaluated.
(See
page 22.60
for an example of a
RETRIEVE, BEFORE, and AFTER are implemented as lispxmacros.
SNDMSG, TECO, and EXEC are
subsys
(section 21),
Finally,
DIRECTORY
SY and
DIR
commands
lisp~nacros
lispxmacro).
In addition, LISP,
which perform the corresponding calls to
and CONTIN is a lispxmacro which performs (SUBSYS T).
are
lispxrnacros which
respectively.
OIR
can
perform the
be
given
EXEC,
SYSTAT,
arguments,
and
e.g~,
DIR *.SAV;*.
84------------------------------··---------------------------------------------In case archivefn needs tOI examine the value of the event, its side
effects,
lists.
etc.
See page 22.44 for discussion of the format of history
22.34
*
*
lispxuserfn
*
provides a way for a user function to process
selected inputs.
When ~xlJserfn i.s set to T, it is applied 36 to all inputs not recognized as
one of the commands described above.
If lispxuserfn decides to handle this
input, it simply processes it (the event was already stored on the history list
before lispxuserfn was called), sets
returns T.
store
lis.~
lispxvalue
lisp~value
to the value for the event, and
will then know not to call eval or
into
the value slot for
the
~,
event,
lispxuserfn returns NIL, lispx proceeds by calling eval or
way.
and will Simply
and print
~
it.
If
in the usual
Thus by appropriately defining (and setting) lispxuserfn, the user can
with a minimum of effort incorporate the features of the programmer's assistant
into his own executive (actually it is the other way around).
35----------------------------------------------------------------------------Like archivefn, lispxuserfn must be both set and defined.
22.35
The following output illustrates such a coupling. 36
**SETQ(ALTFORH (HAPCONC NA50IC (f/L (GETP X 'ALTFORH5]
=NASOICT
(AL26 BE7 C056 C057 C060 C13 H3 MN54 NA22 5C46 534 T144)
**(GIVEMELINE5CONTAININGC08ALT)
.
CITATION
SAMPLE
PHASE
CONSTIT. CONTENT UNIT
510002
OVERALL
C056
40.0
OPH/KG
070-237
C13
8.8
070-228
DEL
DPH/KG
H3
314.0
HN54
28
[1]
**GETP(COBALT ALTFORHS)
(C056 C057 C060 C13 H3 MN54 NA22 5C46 534 T144)
**UNOO MAPCONC
SETQ UNDONE.
**REOOGETP
(C056 C057 C060)
**REOO COBALT
SAMPLE
PHASE
CONSTIT. CONTENT
UNIT
510002
OVERALL
C057
40.0
DPM/KG
S10003
OVERALL
CO
15.0
14.1
C056
43.0
DPM/KG
43.0
C057
C060
1.0
**USE MANGANESE FOR COBALT
[3]
[2 ]
TAG
0
0
[4]
[5]
[6]
CITATION
070-237
070-203
070-216
070-237
070-241
TAG
0
0
0
0
The user is running under his o'm executive program which accepts requests in
the form of sentences, which it first parses and then executes.
The user first
'innocently' computes a list of all ALTERNATIVE-FORMS for the elements in his
system [1].
He then inputs a request in sentence format [2] expecting to see
under the column CONSTIT. only cobalt, CO, or its alternate forms, C056, C057,
or C060.
Seeing C13. H3, and f1N54 , he aborts the output, and checks the
property ALTFORH5 for COBALT [3].
The appearance of C13, H3, MN54, he aborts
the output, and checks the property ALTFORHS for COBALT [3].
The appearance of
C13, H3. MN54 et aI, remind him that the mapconc is destructive, and that in
the process of making a list of the ALTFORMS. he has inadvertently· strung them
all together.
Recovering from this situation would require him to individually
i~-----------------------------------------------------------------------------
The output is from the Lunar Sciences Natural Language Information System
being developed for the NASA Manned Spacecraft Center by William A. Woods
of Bolt Beranek and Newman Inc., Cambridge, Mass.
22.36
examine and correct the ALTFORMs for each element in his dictionary. a tedious
process.
ALTFORM
Instead, he can simply UNDO HAPCONC, [4] check
has
continue.
been
corrected [5],
to make sure the
then redo his original request
[6]
and
The UNDO is possible because the first input was executed by lispx;
the (GIVE ME LINES CONTAINING COBALT) is possible because the user defined
lispxuserfn appropriately; and the REDO-and USE are possible because the
(GIVE ME LINES CONTAINING COBALT) was stored on the history list before it was
transmitted to lispxuserfn and the user's parsing program.
lispxuserfn is a function of two arguments,
~
and line, where x is the first
expression typed, and line the rest of the line, as read by readline (see page
22.47).
For example, if the user types FOO(A B C),
if the user types (FOO A B C),
types FOO ABC,
~:FOO
and line=«A Be»;
~=FOO,
ABC), and line=NILj and if the user
~=(FOO
and line=(A B C).
Thus in the above example, lispxuserfn would be defined as:
[LAMBDA (X LINE)
(COND
«AND (NULL LINE)
(lISTP X»
(SETQ LISPXVAlUE (PARSE X»
T]
Note
that
since
lispxuserfn
1s called for
each
input
(except
for
p.a.
commands). it can also be used to monitor some condition or gather statistics.
*
*
In addition to saving inputs and values, lispx saves most system ,messages on
the history list, e.g.
FILE CREATED --, (fn REDEFINED), (var RESET), output of
TIME, BREAKDOWN, STORAGE, DWIM messages,
event,
this
functions
output
1s replicated.
lispxpr1nt,
lispxprinl,
etc.
When
printhistory prints
This facility is
lispxpr1n2,
22.37
implemented via
11spxspaces,
11spxterpri,
the
the
and
lispxtab. 37 In addition to performing the corresponding output operation, these
functions
store an appropriate expression on the history event under
the
property LISPXPRINT. 88 This expression is used by printhistory to reproduce the
output.
•
*
*
In addition to the above features. lispx checks to see if car or cdr of NIL
o~
car of T have been clobbered, B.nd if so, restores them and prints a message.
Lispx
also
performs
spelling corrections using lispxcoms,
a
list
of
its
commands, as a spelling list whenever it is given an unbound atom or undefined
function, i.e. before attempting to evaluate the input. 89
22 .. 6
Undoing
The UNDO capability of the proglrammer's assistant 1s implemented by requiring
that each operation that is to be undoable be responsible itself for saving on
the history list enough information to enable .reversal of its side effects.
other words.
the assistant does not
destructive operation,
i.e.
I
In
know' when it is about to perform a
it is not constantly checking or anticipating.
Instead, it simply executes operations, and any undoable changes that occur are
87------------------------------'-------~---------------------------------------
In fact, all six of these functions have the same definition. When called,
this function looks back on the stack to see what name it was called by,
and determines what to do. Thus, if the user wanted to make any other
output function, e.g. printdef, record its HOVD(LISPXPRINT LISPXPRINTOEF),
and then use lispxpr1ntde[ for printdef.
(This will work only for
functions of three or fewer arguments.)
38
unless lispxprintflg is NIL.
39
lisp2S is also responslblefor rebinding helpclock, used by breakcheck,
Section 16, for computing the amount of time spent in a computation, in
order to determine whether to go into a break if and when an error occurs.
22.38
automatically saved· on the history list by the responsible function. 40 The
operation of UNDOing, which
involves recovering the saved information and
performing the corresponding inverses, works the same way, so that the user can
UNDO an UNDO, and UNDO that etc.
At each point, until the user specifically requests an operation to be undone,
the assistant does not know, or care, whether information has been saved to
enable the undoing.
Only when the user attempts to undo an operation does the
ass is tant check to see whether any 'information has been saved.
I f none has
been saved, and the user has specifically named the event he wants undone, the
assistant types NOTHING SAVED. (When the user simply types UNDO, the assistant
searches for the last undoable event, ingnoring events already undone as well
as UNDO operations themselves.)
This implementation minimizes the overhead for undoing.
Only those operations
wh ich actually make changes are affected, and the overhead 1s small: two or
three cells of storage for saving the information, and an extra function call.
However,
even
this small price may be too expensive if the operation
is
sufficiently primitive and repetitive, i.e. if the extra overhead may seriously
degrade the overall performance of the program. 41 Hence not every destructive
operation in a program should necessarily be undoable; the progranuner must be
allowed to decide each case
individ~ally.
40---------------------------------------------------------------------------When the number of changes that have been saved exceeds the value of
#undosaves (initially set to 50), the user is asked if he wants to continue
savin9lthe undo information for this event. The purpose of this feature is
to· avoid tying up large Quantities of storage for operations that will
never need to be undone. The interaction is handled by the same routines
used by DWIM, so that the input buffers are first saved and cleared, the
message typed, then the system waits dwimwait secon~s. and if there is no
response, assumes the default answer. which in this case 1s NO. Finally
the input buffers are restored. See page 22.56 for details.
41
The rest of the discussion applies only to lispx; the editor handles
undoing itself 1n a slightly different fashion. as described on page
22.61.
22.39
Therefore for each primi tive dC3structive operation, we have implemented two
separate
functions,
one
which
always
saves
information,
i.e.
is
always
undoable, and one which does n01~. e.g. Irplaca and rplaca, Iput and ru!!.42 In
the various system packages, the appropriate function is used.
For example,
break uses Iputd and Iremprop so as to be undoable. and OWl" uses Irplaca and
Irplacd, when it makes a correction. 43 Similarly the user can simply use the
corresponding I function if he wants to make a destructive operation in his own
program undoable.
When the I
function is called,
it will save the undo
information in the current event on the history list.
However, all operations that are tuped in to lispx are made undoable, simply by
subs ti tuting the corresponding I funct'ion 44 for any destructive function
through-out the input. 46 For example, on page 22.8, when the user typed
(MAPCONC NASOIC (F/L ... »
evaluated.
it
was
(/MAPCONC NASOIC (F/L •.• »
that
was
Since the system cannot know whether efficiency and overhead are
serious considerations for the execution of an expression in a user program,
the user must decide, e.g. call Imapconc if he wants the operation undoable.
42------------------------------'----------------------------------------------The 'slash' functions eUI~rently implemented are laddprop, lattach,
Idreverse, /dsubs~. Ileone, Imapeon, Imapcone, Imovd, Inconc,
/put, Iputd, Iputdg, Iputhash, Iremprop, Irplaca, Irplacd, /set,
/seta, /setd, and Itcone. Note that Isetq and /setqq are not included. If
the user wants a set operatlon undoable in his program, he must see /set,
or /rplaca.
/dre!!l~:Y.~'
/~c~~£!,
48
44
45
The effects of the following functions are always undoable (regardless of
whether or not they are typ1ed in): define, defineq, defc (used to give a
function a compi led code defini tion), deflist. load, savedef, unsavedef,
broilk. unbreak, rebreak, trill, breakin, unbreak.Til""; changename, edi tfns,
editf, editv, editp. edite, ~~ditl, esubst, advise, unadvise, readvise, plus
any changes caused by DWIM.
Since there is no Isetq, set~s appearing in type-in are handled specially
by substituting a call to sa,.Y!!,.et, page 22.43.
The subs ti tution is performc!d by the function lispx/, described on page
22.58.
22.40
However, expressions that are typed-in rarely involve iterations or lengthy
computations directlu.
Therefore~
if all primitive destructive functions that
are immediately contained in a type-in are made undoable, there will rarely be
a significant loss of efficiency.
eva lua ting it.
Thus lispx scans all user input before
and subs ti tutes the corresponding undoable function
primitive destructive functions.
for all
Obviously with a more sophisticated analysis
of both user input and user programs, the decision concerning which operations
to
make
undoable
could
be
better advised.
However,
we
configuration described here to be a very satisfactory one.
have
found
the
The user pays a
very small price for being able to undo what he 'types in, and if he wishes to
protect himself from malfunctioning in his own programs,
he can have his
program specifically call undoable functions, or go into testmode as described
next.
Testmode
Because of efficiency considerations, the user may not want certain functions
undoable after his program becomes operational.
However, while debugging he
may find it desirable to protect himself against a program running wild, by
making
primitive
destructive
operations
undoable.
The
function
testmode
provides this capability by temporarily making everything undoable.
testmode[flg]
testmode[ld redefines all primitive destructive
functions
with their corresponding undoable
versions and sets testmodeflg to T.
testmode[ ]
restores the oriij~al defini tions, and sets
testmodeflg to NIL.
---------------------------------~~------~---------~--------~--------~--------46
i.e. the 'slash' functions; see footnote on page 22.40.
47
testmode will have no effect on compiled mapconc's, since they compile open
with frplacd's.
22.41
Note that setq' s are not undoab]le, even in testmode.
To make the corresponding
operation undoable in testmode, set or rplaca should be used.
Undoing Out of Order
Irplaca and Irplacd operate by saving the pointer that is to be changed and its
original contents (i.e.
Irplac,~
Irplaca and Irplacd simply
(RPLACA
Faa
saves £!!: and Irplacd saves cdr).
re~.tores
the pointer.
Thus,
Undoing
if the user types
1), followed by (RPLACA FOO Z), then undoes both events by undoing
the most recent event first, then undoing the older event, FOO will be restored
to its s ta te before either lli.aca operated.
However if the user undoes the
first event, then the second event, (CAR FOO) will be 1, since this is what was
in car of FOO before (RPlACA FOO Z) was executed.
Similarly,
if the user
performs' (NCONCI FOO 1) then (NCONC1 Foo 2), undoing just (NCONCI FOO 1) will
remove both 1 and 2 from FOO.
The problem in both cases is that the two
operations are not 'independent.' In general, operations are always independent
if they affect different list:; or different sublists of the same list. 48
Undoing in reverse order of execution, or undoing independent operations, is
always
guaranteed
to
do
the
'right'
thing.
However,
undoing
dependent
operations out of order may not always have the predicted effect.
48----------------------------------------------------------------------------Property list operations, (i.e. put, addprop and remprop) are handled
spec ia lly so that they are always independent, even when they affect the
same property list. for example, if the user types PUT(FOO FIEI FUMl) then
PUT(FOO FIE2 FUM2), then undoes the first event, the FIEZ property will
remain, even though COR(FOO) may have been NIL at the time the first event
was executed.
22.42
Saveset
Sctq's
are
made
undoable
on
type
in
by substituting a
cal~
to
savesct
(described in detail on page 22.55), whenever setq is the name of the function
to be appl ied, or car of the form to be evaluated.
In addition to saving
enough information on the history list to enable undoing, saveset operates in a
manner analogous to savedef when it resets a top level value, i.e. when it
changes a top level binding from a value other than NOBINO to a new value that
is not equa! to the old one.
In this case, saveset saves the old value of the
variable being set on the variable's property list under the property VALUE,
and prints the message (variable RESET).
The old value can be restored via the
function unset,49 which also saves the current value (but does not print a
message).
~
and
Thus unset can be used to flip back and forth between two values.
~
are implemented via calls to·saveset.
Thus old values will be
saved and messages printed for any variables that are reset as the result of
l~ading a
file. 60 Calls to set and ill.qg, appearing in type
in
are
also
converted to appropriate calls to saveset.
For top level variables. saveset also adds the variable to the appropriate
spelling list, thereby noticing variables set in files via
~
or rpaqq, as
well as those set via type in.
~~---------------------~-------------------------------------------------------
Of course, UNDO can be used as long as the event containing this call to
saveset is still active. Note however that the old value will remain on
thEt-property list, and therefore be recoverable via unset, even after the
original event has been forgotten.
50
To complete the analogy with define, saveset will not save old values on
property lists if dfnflg=T, e.g. when load is called with second argument
T, (however. the call to saveset will still be undoable,) and when
dfnflg=ALLPROP, the value is stored directly on the property list under
property VALUE (the latter applies only to calls from ~ and ~).
22.43
22.7
Format and Use of the History List
There are currently two histolry lists,
lispxhistory and edithistory.
Both
history lists have the same format, and in fact, each use the same function,
historysave,
for
recording
implementing
conunands
events,
that
refer
and
to
the
the
same
history
set
list,
of
functions
e.g.
for
historyfind,
printhistory, undosave, etc. 61
Each history list is a list of the form
(!
eventl size mod), where! 15 the
list of events with the most recent event first, event# is the event number for
the mos t
recent event on !,
maximum length of
on
page
is the size of the time-slice,
i. e.
the
!. and mod is the highest possible event number (see footnote
22.8) .
(NIL 0 30 100).
~iize
lispxhistory
and
edithistory
are
both
initialized
to
Setting lispxhistory or edithistory to NIL is permitted, and
simply disables all history features, i.e. lispxhistory and edithistory act
like flags as well as repositories of events.
Each individual event on !
is a list of the form (input id value • props),
where input is the input sequence for the event, as described on page 22.17-19,
id the prompt character, e.g. ~, :, .,62 and value is the value of the event,
and is initialized to bell. 68
51----------------------------------------------------------------------------A third history list, archivelst, is used when events are archived, as
described on page 22.27.
It too uses the same format.
62
id is one of the arguments to lispx and to historysave. A user can call
1 ispx gi vi ng it any prompt character he wishes (except for It, since in
certain cases, lispx must use the value of id to tell whether or not it was
called from the editor.) For example, on page 22.36, the user's prompt,
character was **.
53
On edithistory.
conunand.
this field is used to save the side effects of each
22.44
I!..ro~
is a property list, i.e. of the form (property value property value --).
props can be used to associate arbitrary information with a particular event.
Currently,
the
properties SIDE,
GROUP,
ERROR, and lISPXPRINT are being used.
the side effects of the event.
undolispx,
page
22.58).
The
HISTORY,
PRINT,
USE-ARGS,
••• ARGS,
The value of property SIDE is a list of
(See discussion of undosave, page 22.56, and
HISTORY and GROUP
properties
commands that reexecute previous events, i.e. REDO, RETRY, USE,
are
... ,
used
for
and FIX.
The value of the HISTORY property is the history command itself, i.e. what the
user actually typed, e.g.
printing the event.
REDO FROM F, and is used by the 11 command for
The value of the property PRINT is also for use by the 11
command. when special formatting is required, for example, in printing events
corresponding to the break commands OK, GO, EVAl, and 1=_
USE-ARGS and •.• ARGS
are used to save the arguments and expression for the corresponding history
command.
ERROR is used by the $ command.
lISPXPRINT is used to record calls
to lispxprint, lispxprinl. et aI, See page 22.37.
When lispx is given an input, it calls historysave to record the input in a new
event. 54 Normally, historysave returns as its value cddr of the new event, i.e.
car of its value is the value field of the event.
lispx binds lispxhist to the
value of historysave, so that when the operation has completed, lispx knows
where to store the value, namely in £!r of lispxhist. 65 lispxhist also provides
access
to
functions
the
property list for the current event.
are
all
implemented
to
call
undosave,
For example,
which
simply
the
adds
I
the
corresponding information to lispxhist under the property SIDE, or if there is
no property SIDE, creates one, and then adds the information.
66
Note that by the time it completes, the operation may no longer correspond
to the most recent event on the history list. For example, all inputs
typed to a lower break will appear later on the history list.
22.45
After binding lispxhist, lispx
the input, stores its value in car of
ex~cutes
lispxhist, prints the value, and returns.
When the input is a REOO, RETRY, USE, •.• , or FIX command, the procedure is
similar, except that the event is also given a GROUP property, initially NIL,
and a HISTORY property, and
lis~
simply un reads the input and returns.
When
the input is 'reread', it is historysave, not lispx, that notices this fact,
and finds the event from which the input originally came. 66 historysave then
adds a new (value . props) ent.ry to the GROUP property for this event, and
returns this entry as the 'new (.vent. I lispx then proceeds exactly as when its
input was typed directly, i.e. it binds lispxhist to the value of historysave,
executes the input. stores the value in car of lispxhist. prints the value, and
returns.
input,
In fact, lispx never notices whether it is working on freshly typed
or
input
that
was
reread.
Similarly,
undosave
will
store
undo
information on lispxhist under the property SlOE the same as always, and does
not know or care that lispxhi:st is not the entire event, but one of the
elements of the GROUP property.
Thus when the event is finished,
its entry
will look like:
(input id value HISTORY command GROUP «value1 SIDE side1)
(value2 SIDE side2)
... ) )
67
This implementation removes the burden from the function calling historysave of
distinguishing between new input and·reexecution of input whose history entry
60------------------------------··--------------------------------------------If t-istory~_ave cannot find the event, for example if ,a user program unreads
the input directly, and not via a history command, historysave proceeds as
though the input were typed.
67
In this case, the value field is not being used; valueof instead collects
each
of
the
values
from
the
GROUP
property,
i.e.
returns
mapcar[get[event;GROUP];CAR]. Similarly, undo operates by collecting the
SIDE properties from each of the elements of the GROUP property. and then
undoing them in reverse order.
22.46
has already been set up.68
22.8
lispx and readline
lispx
is called with the first expression typed on a line as
its first
argument, lispxx.
If this is not a list, lispx olwollS does a readline, and treats lispxx plus, the
line as the input for the event, and stores it accordingly on the history
list. 69 Then it decides what to do with the input. i.e. if it is not recognized
as a command,
a lispxmacro,
or is processed by lispxuserfn, call eval or
apply.60 readline normally is terminated either by (1) a carriage return that
is not preceeded by a space, or (2) a list that is terminated by a ], or (3) an
unmatched ) or ], which is not included in the line.
However, when called from
lispx, readline operates differently in two respects:
(1)
If the line consists of a single ) or ], readlinereturns (NIL)
instead of NIL, i.e. the) or lis included in the line.
This permits
the user to type FOO) or Foo], meaning call the function' FOO with no
arguments, as opposed to FOO) (FOOcarriage-return). meaning evaluate
the variable FOO.
(2)
If the first expression on the line is a list that is not preceded by
58----------------------------------------------------------------------------Although we have not yet done so, this implementation, i.e. keeping the
various 'sub-events' separate with respect to values and properties, also
permits constructing commands for operating on just one of the sub-events.
69
If lispxx is a list car of which is LAMBDA or NLAMBDA,
lispxrcad to obtain the arguments.
60
If the input consists of one expression, eval is called; if two, apply; if
more than two, the entire line is treated as a single form and eval is
called.
22.47
lispx calls
any spaces, the list terminates the line regardless of whether or not
it is terminated by].
This permits the user to type EDITF(FOO) as a
single input.
Note that if any spaces are inserted between the atom and the left parentheses
or . bracket, readl ine will assume that the list does not terminate the line.
This is to enable the user to type a line command such as USE (FOO) FOR FOO. In
this case, a carriage return wtll be typed after (FOO) followed by"
described in Section 14.
It
as
Thererore, if the user accidentially puts an extra
space between a function and its arguments, he will have to complete the input
with another carriage return. e.g ..
.. EOITF_(FOO)
•••.>
EDI'T
*
22.9
Functions
lispx[ lispxx; lispxid; lispxxmacro!;; lispxxuserfn ]81
lispx is like
eval/~.
It carries out a single
computation,
and returns its value.
The first
argument, lispxx is the result of a single call to
lispxread.
lispx will call readline, if necessary
as described on page 22.47.
lispx prints the
value of the computation, as well as saving the
61------------------------------..
---------------------------------------------lispxid corresponds to id on page 22.44. Lispx also has a fifth argument,
lispxflg, which is used by the E command in the editor.
22.48
input and value on lispxhistory.62
If lispxx is a history command, lispx executes the
command, and returns bell as its value.
If the value of the fourth argument, lispxxmacros,
is not NIL,
it
is used as
the
lispx macros,
otherwise the top level value of lispxmacros is
used.
If
the
lispxxuserfn,
lispxuserfn.
value
is
not
of
the
NIL,
fifth
. it
is
argument,
used
as
In this case, it is not necessary to
both set and define lispxuserfn as described on
page 22.35.
The overhead for a call to lispx is approximately 17 milliseconds, of which 12
milliseconds are spent in maintaining the spelling lists.
In
INTERLISP, the user pays 17 more milliseconds for each eval or
other words, in
~
input over
a conventional LISP executive, in order to enable the features described in
this chapter.
userexec[lispxid;lispxxmacros;lispxxuserfn]
repeatedly calls lispx under errorset protection
specifying
lispxxmacros
and
lispxxuserfn,
and
using lispxid (or .. if lispxid=NIL) as a prompt
character.
Userexec is exited via the lispxmacro
OK, or else with a retfrom.
62----------------------------------------------------------------------------Note that the history is not one of the arguments to lispx, i.e. the editor
must bind (reset) lispxhistory to edithistory before calling lispx to carry
out a history command.
.
Lispx will continue to operate as an eval/~ function if lispxhistory is
NIL. Only those functions and commands that involve the history list will
be affected.
22.49
lispxread[file]
is a generalized read.
per"forms
value.
call
read[ file],
If readbuf=NIL, lispxread
which
it
returns
as
its
( I f the user types control-U during the
to read,
lispxread calls
the
editor
and
returns the edited value.)
If readbuf is not NIL, lispxread 'reads' the next
expression on readbuf, i.e. essentially returns
(PROGl (CAR READBUF)
(SETQ READBUF (CDR READBUF»).63
readline,
reading.
described
in Section 14,
also uses
this
generalized
notion
of
When readbuf is not 'UL, readline 'reads' expressions from readbuf
until it e1 ther reaches the end of readbuf, or until it reads a (VAG 0).
both cases, it returns a list of the expressions it has 'read'.
In
(The (VAG 0)
is not included in the list.)
When readbuf is not NIL, both lispxread and readline actually obtain their
input by performing (APPLY*
set to READ.
LISI~XREADFN
FILE), where lispxreadfn is initially
Thus. if the user' wants lispx, the editor, break, et al to do
their reading via a different input function,
e.g. uread, he simply sets
lispxreadfn to the name of that function (or an appropriate LAMBDA expression).
lispxreadp[ fIg]
is a generalized readp.
If
f~=T,
lispxreadp
returns T if there is any input waiting to be
'read', a la lispxread.
If f!.g=NIL,
lispxreaQQ
returns T only if there is any input waiting to be
'read' on thts ltne. In both cases, leading spaces
63--~~~~~~--~~~~--~;;~~~:~;;;~~~~;--;;~~;~;:--;;--;;~;;;;~~;~--b;--(VAG-O):--;;;
ignored, i.e. skipped. Lispxread also sets rereadflg to NIL when it reads
via read, and sets rereadflg to the value of readbuf when rereading.
22.50
are ignored, i.9. skipped over with reade, so that
if only spaces have been typed. lispxreadp will
return NIL.
lispxunread[lst]
unreads 1st, a list of expressions to be read.
If
readbuf is not NIL. 1ispxunread attaches 1st at
the front of readbuf, separating it from the rest
of readbuf with a (VAG 0).
The definition of
lispxunread is:
(LISPXUNREAD
[LAMBDA (lST)
(SETQ READBUF (COND
«NULL READBUF)
LST)
(T (APPEND LST (CONS (VAG 0)
READBUF])
promptchar[id;flg;hist]
prints the prompt character ide
promptchar will not print anything when the next
input will be 'rereado, i.e.
readbuf is not NIL.
promptchar will also not print when readp[ ]=T.
unless f.!.9 is T.
Thus the editor calls promptchar with flg=NIL so that extra
when
the user types several commands on one line.
promptchar with f!9=T since
it always wants the
~
~'s
are not printed
However,
evalqt calls
printed
(except when
'rereading').
Finally. if prompt#flg is T and hist is not NIL,
promptchar prints the current event number (of
hist) before printing id.
22.51
lispxeval[lispxform;lispxid] eVilluates
lispxform
(using
eval)
the
same
as
th(mgh it were typed in to 1ispx, i •e . the event
is recorded, and the evaluation is made undoable
by
substituting
the
slash
functions
for
the
corresponding destructive functions, as described
on page 22.40.
lispxeval returns the value of the
form, but does not print it.
historysave[history;id;inputl;input2;input3;props]
records one event on history.
NIl.,
input
the
is'
If input1 is not
of
the
form
(inputl input2 • input3).
If input1 is NIL, and
input2 is not NIL,
input
(input2 . input3).
the
is of the
form
Otherwise, the input is just
!ill!ut3.
histor~save
creates
a
new
event
with
the
corresponding input, id, value field initialized
to bell, and I!!.f!J!! • If the histor~ has reached
its full size, the last event is removed and
canlnibalized.
The value of historysave is cddr of the event.
How1ever, if rereadflg is not NIL, and is a tail of
the input of the most recent event on the history
lis't, and this event contains a GROUP property,
historysave does not create a
new event,
but
simply adds a (bell. props) entry to the GROUP
property and returns that entry.
on I)age 22.46.
22.52
See discussion
lispxfind[history;line,type;backup]
line is an event specification,
~
specifies the
format of the value to be returned by lispxfind,
and can be either ENTRY, ENTRIES, COPY, COPIES,
INPUT, or REDO.
historyfind
lispxfind
lispxfind parses line, and uses
to
find
then
the
corresponding
assembles
and
events.
returns
the
appropriate structure.
lispxfind incorporates the following special features:
(1)
if backup=T, lispxfind interprets line in the context of the history list
before the current event was added.
This feature is used, for example, by
valueof, so that (VALUEOf -1) will not refer to the valueof event itself;
(2)
if line=NIL and the last event is an UNDO, the next to the last event is
taken.
(3)
This permits the user to type UNDO followed by REDO or USE;
lispxfind recognizes @@, and substitutes archivelst for history (see page
22.14); and
(4) lispxfind recognizes @, and retrieves the corresponding event(s) from the
property list of the atom following @ (see page 22.14).
historyfind[lst;index;mod;x;y]
searches
1st
and
returns
the
tails
of
beginning with the event corresponding to x.
1st
1st,
index, and mod are as described on page 22.44.
~
is an
event address,
22.11-14,
22.53
e. g.
as
described
(43), (-1),
on
page
(fOO FIE),
(LOAD" FOO), etc. 64 If historyflnd cannot find !,
it generates an error.
hi~;t
entry#[hist;x]
is a history list, i.e. of the form described
on page 22.44.
i. Et.
x is one of the events on hist,
(HEHB X (CAR HIST»
The value of
is true.
en1;ryl is the event number for !.
valueof[x]
is an nlambda, nospread function for obtaining the
value
of
the
(VPILUEOF -1),
event
speci fied
(VALUEOF LOAD 1),
by
etc.
2!,
e. g.
valueof
ret.urns a list of the corresponding values if x
specifies a multiple event.
changeslice[n;history]66
changes time-slice for history to!!..
is NIL, changes both edithistory and
Note:
lispxhisto~y.
the effect of increasing a time-slice is gradual: the history list is
simply allowed
forgotten.
of
If history
the
However,
to grow to
the corresponding length before any events
are
Decreastng a time-slice will immediately remove a sufficient number
older events
changeslice
recoverable.
to bring the history list down
is
undoable,
so
that
these
to
the
proper
size.
events
are
(temporarily)
Thus if the user wants to recover the storage associated with
these events without wai ting !! more events for the changeslice event to be
forgotten, he must perform a FORGET command.
64------------------------------~----------------------------------------------
If y.. is given,
e.g.
~=(FOO
65
~=(FOO
the event address is the list difference between x and X:,
FIE AND \ -1), l=(AND \ -1)
is
equivalenf
to
FIE), y"=NIL.
changeslice has
changeslice.
a
third
argument
used
22.54
by
the
system
for
undoing
a
saveset[name;valuejtopflg;flg]
an undoable set.
(see page 22.43).
savesct scans
the pushdown list looking fpr the last binding of
~,
sets name to value, and returns value.
I f the, binding changed was a top leve 1 binding,
name
is added to spellings3
(see Section 17).
Furthermore. if the old value was not NOBIND, and
was also not equal to the new value, saveset calls
the file
package to update the necessary file
records.
Then.
if dfnflg is not equal
saveset prints (name RESET),
and saves
value on the property list of
property VALUE.
~,
to
T,
the old
under the
If f1Jl=NOPRINT. saveset saves the
old value, but does not print the message.
This
option is used by unset.
If topflg=T, saveset operates as above except that
it does not scan the pushdown list but goes right
to name's value cell, e.g. rpaqq[x;y]' is simply
saveset[x;y;T].
When topflg is T, and dfnflg is
ALLPROP and the old value was not NOBINO, saveset
simply stores value on the property list of
~
under the property VALUE. and returns value.
This
option
is
used
for
loading
files
without
disturbing the current value of variables (see
Section 14).
If flg=NOSAVE, saveset does not save the old value
on the property list, nor does it add name to
spellings3.
undoable.
However, the call to saveset is still
This option is used by Iset.
22.55
unset[name]
if
~
does not contain a property VALUE, unset
generates an error.
with
the
~,
Otherwise unset calls saveset
property value,
topflg=T,
and
flg=NOPRINT.
undosave[undoform]66
if lispxhist is not NIL (see discussion on page
22.45), and get[lispxhist;SIOE] is not equal to
NOSAVE, undosave adds undoform to the value of the
property
SIDE
on
lispxhist,
creating
a
property if one does not already exist.
of undoform is (fn . args), 67 i. e.
The form
undoform is
by
undone
SIDE
performing
apply[car[undoform];cdr[undoform]].
example~
For
if the definition of FOO is def, Iputd[FOO;newdef]
cause
will
a
undo save
call
with
undoform =(/PUTO FOO def).
car
of
the
SIDE
property
'undosaves',
i.e.
length
of
is
the
cdr
of
number
the
property. which is the list of undoforms.
of
SIDE
Each
call to undosave increments this count, and adds
undoform to the front of the list, i.e. just after
the count.
When the count reaches the value of
lundosaves
(initially 50),68
undosave
prints
a
66----------------------------------------------------------------------------Undosave has a second optional argument. histentry, which can be used to
specify lispxhist directly. saving the time to look it up.
histentry and lispxhist are NIL. undosave is a NOP.
67
Except for Irplnode, as described below.
68
lundosavcs=NIL is equivalent to #undosaves=infinity.
Z2.56
If both
message asking the user if he wants to continue
saving.
If
the user
answers
NO or defaults,
undosave makes NOSAVE be the value of the property
SIDE, which disables any further saving for th is
If the user answers YES, undosave changes
event.
the count to -1, which is then never incremented,
and continues saving. 69
lrplnode[x;a;d]
Undoably
Value is
performs
and
rplacd[x;d].
The principle advantage of Irplnode
~.
is that when
rplaca[x;a]
~
is a list, Irplnode saves its undo
information as - cons[x;cons[car[x);cdr[x]]],
(x originalcar • originalcdr),
and
1.e.
therefore
requires only 3 cells of storage, instead of the 8
that would be required for a Irplaca and a Irplacd
nE~w/fn[
fn]
that
saved
earlier. 70
their
information
Irplnode has a
BLKLIBRARYOEF~
as
described
After the user has defined Ifn, new/fn performs
the necessary housekeeping operations to make fn
be undoable.
70
Actually, Irplaca and Irplacd also use this format for saving their undo
information when their first arguments are lists. However, if both a
Irplaca and Irplacd are to be performed, it 1s still more efficient to use
Irplnode (3 cells versus 6 cells).
22.57
For example, the user could define Iradix as
perform
then
(LAMBDA (X) (UNDOSAVE (LIST (QUOTE IRADIX) (RADIX X») and
new/fn[radix], and radix would then be undoable when typed in or in testmode.
lispx/[x;fn;vars]
performs
the
substitution
of
thEI name of a function, and
is' its argument
!
If fn is NIL, ! is a form.
returns
substitutions.
for
If fn is not NIL, it is
destructive functions.
lis;t.
functions
I
In both cases,
appropriate
the
with
Vars is a list of bound variables
(optional).
lis,pxl incorporates information about the syntax
and
semantics
example,
of
INTERLISP
expressions.
it does not bother
to make
For
undoable
ope'rations involving variables bound in x.
It
also
be
knows
that
substitution
should
not
per'formed inside of expressions f.!!.!: of which is
QUOTE,
OEFINEQ,
etc. 71
BREAK,
Similarly,
substitution should be performed in the arguments
for' functions like
ma~c,
!:.l!!9., etc., since these
contain expressions that will be
applied.
For
example,
mapc[(FOOl F002 F003);PUTO]
if
the
the
evaluated
user
putd
or
types
must
be
replaced by Iputd.
undolispx[line]
lin! is an event specification.
undolispx is the
function that executes UNDO commands by calling
undolispxl on the appropriate entry(s).
~i-----------------------------------------------------------------------------
Any member of the list nosubstfns.
22.58
undolispxl[event;flg]
undoes pne event.
The value of undolispxl is NIL
if there is nothing to be undone.
If the event is
already undone, undolispxl prints ALREADY UNDONE
and returns T.72 Otherwise, undolispxl undoes the
event,
prints a message,
e.g. SETQ UNDONE,
and
returns T.
Undoing an event consists of mapping down (cdr of) the property value for SIDE,
and for each element, applying £!!r. to cdr, and then marking the event undone by
attaching (with lattach) a NIL to the front of its SlOt property.
Note that
the undoing of each element on the SIDE property will usually cause undosaves
to
be
added
to
the
current
lispxhist,
thereby enabling
the
effects
of
undolispxl to be undone.
undonlsetQ[form]
is
an
nlambda. function
similar
to
nlsetq.
undonlsetq evaluates form, and if no error occurs
during the evaluation,
returns
list[ eval[ form]]
and passes the undo information from form (if any)
upwards. 78 If an error does occur, the value of
undonlsetq
functions
is NIL,
during
and any changes made
the
evaluation
of
form
by
I
are
undone.
72--i;-;i~:~-~~~-~h;-;~;~~-~;-~i;;;~;-~~~~~;~-~;-~;-;~-~~~~-~~~~~~~-~~~~i~~~~~
takes no action and returns NIL. Undolispx uses this option to search for
tho last event to undo. Thus when line=NIL, undolispx simply searchos
history until it finds an event for which undo.!gm returns T, i.s.
undolis~x performs (SOME (COAR LISPXHISTORY) (F/L (UNDOLISPXl X T»)
73
Actually, undonlsetq does not rebind lispxhist, so that any undo
information is stored directly on the history event, exactly as though
thore were no undonlsetq. Instead, .undonlsetg simply marks the state of
the undo information when it starts, so that if an error occurs, it can
then know how much to undo. The purpose of this is so that if the user
control-D's out of the undonlsetq, the event is still undoable.
22.59
undonlsetq compiles open.
undonlse.!.g will operate even if lispxhistory or
lispxhist are NIL, or if #undosaves is or has been
exceeded for this event.
Note that undonlsetq provides a limited form of backtracking.
printhistory[history;line;skipfn;novalues]
line
is
an
event
printhistory
specification.
prints the events on history specified by line,
e.g.
(-1 THRU -10).
skipfn
is
an
(optional)
functional argument that is applied to each event
before printing.
If its value is true, the event
is skipped, i.e. not printed.
If novalues=T, or
!!QYalues applied to the corresponding event is
true, the value is not printed.?4
For example, the following lispxmacto will define 11' as a command for printing
the history list while skipping all 'large events' and not printing any values.
(11' (PRINTHISTORY LISPXHISTORY LISPXLINE
(FUNCTION (LAMBDA (X)
(IGREATERP (COUNT (CAR X» 5»)
T) )
74------------------------------··---------------------------------------------For example, novalues is T when printing events on edithistory.
22.60
22.10
The Editor and the Assistant
As mentioned earlier,
all of the remarks concerning 'the assistant'
equally well
interactions with evalqt, break or the
to
us~r
apply
ed~tor.
The
differences between the editor's implementation of these features and that of
Jispx are mostly obvious or inconsequential.
However. for completeness, this
section discusses the editor's implementation of the programmer's assistant.
The
edi tor uses promptchar to print its prompt character,
1 ispxreadp,
input~
and readline for obtaining inputs.
and
lispxread,
When the editor is given an
it calls historysave to record the input in a new event on its history
list, edithistory.76 Edithistory follows the same conventions and format as
lispxhistory.
value
field
However, since edit commands have no value, the editor uses the
for
saving side effects,
rather than storing them under
the
property SIDE.
The editor processes DO, IE, IF, and IN commands itself, since lispx does not
recognize these commands.
below.
The editor also processes UNDO itself, as described
,All other history commands 76 are simply given to lispx for execution,
after first binding (resetting) lispxhistory to edithistory.
The editor also
76-------------------------~---------------------------------------------------
Except that the atomic commands OK, STOP, SAVE, P, 7, PP and E are not
recorded. In addi tion, number commands are grouped together in a single
event.
For example. 3 3 -1 is considered as one command for changing
position.
76
as indicated by their appearance on historycoms, a list of the history
commands. editdefault interrogates historycoms before attempting spelling
correction. (All of the commands on historycoms are also on editcomsa and
cditcom~! so that they can be corrected if misspelled in the editor.) Thus
if the user defines a lispxmacro and wishes it to operate in the editor as
well, he need simply add it to historycoms. For example, RETRIEVE is
implemented as a lispxmacro and works equally well in lispx and the editor.
22.61
calls lispx when given an E command as described in Section 9. 77
The major implementation diffel-ence between the editor and lispx occurs in
undoing.
Edithistory is a list of only the last!!. commands, where!!. is the
value of the time-slice.
However the editor provides for undoing all changes
made in a single editing session, even if that session consisted of more than !!.
edit commands.
Therefore, the 'editor saves undo information independently of
the edithistory on a list call
undols t
~ndolst,
(although it also stores each entry on
in the field of the corresponding event on edi this tory.) Thus,
the
commands UNDO, !UNDO, and UNBLOCK, are not dependent on edithistory,78 i.e.
UNDO speci fies undoing the last command on undolst, even if that event no
longer appears on edi th is tory.
history
list
specification.
occurs
when
The only interaction between UNDO and the
the
user
types
followed
by
an
event
In this case, the editor calls lispxfind to find the event, and
then undoes the corresponding entry on undolst.
~peciJied
UNDO
Thus the user can only undo a
command within the scope of the edithistory.
(Note that this is also
the only way UNDO conunands themselves can be undone, that is, by using the
history feature, to specify the corresponding event, e.g. UNDO UNDO.),
The implementation of the actual undoing is similar to the way it is done 1n
I ispx: each command that makes
it
change in the structure being edited does so
via a function that records the change on a variable.
After the command has
completed, this variable contains a list of all the pointers that have been
77------------------------------··---------------------------------------------In this case, the editor us.es the fifth argument to lispx, lispxflg, to
specify that any history cowaands are to be executed by a recursive call to
lisp~, 'rather than by unreading.
for example, if the user types E REDO in
the edi tor, he wants the Itllst event on lispxhistory processed as lispx
input, and not to be unread and processed by the editor.
78
and in fact will work if edithistory=NIL, or even 1n a system which does
not contain lispx at all.
22.62
changed and their original contents.
Undoing that command simply involves
mapping down that list and restoring the pointers.
?oZ.11
The
Statistics
programmer' s ·assistant keeps various statistics about system usage, e.g.
number of lispx inputs, number of undo saves, number of calls to editor, number
of
edit commands. number of p.a. commands. cpu time, console time,
et al.
Tbese can be viewed via the function lispxstats.
lispxstats[]
prints statistics.
The us'er can' add his own statistics to the lis2x statisti.cs via the function
addstnts
0 ..
addstats[statlst]
no spread, nlambda.
of
the
form
(statistic"name. message),
(EOITCALLS CALLS
UNDONE), etc.
in
an
unboxed
StatIst is a list of elements
TO EDITOR)
(UNOOSTATS
e.g.
CHANGES
statistic-name is set to the cell
array,
statistic will be stored.
where
the
corresponding
This statistic can then
be incremented by lispxwatch.
lispxwatch[stat;n]
increments stat by II (or 1 if rr=NIL).
lispxwatch
has a BlKlIBRARYOEF.
The
user can save his statistics for loading into a new system by performing
MAKEFIlE(DUMPSTATS). After the file OUMPSTATS is loaded, the statistics printed
by
.t!~.?USERNAMEFILE.
To
change
an
existing
initialization, or create a new one, a new USERNAMEFILE must be written.
This is accomplished by loading the file USERNAMES, editing usernamelst,
and then performing makeusernames[], which will create new versions of both
USERNAHEFILE and USERNAMES. (Note that the person performing this operation
must therefore either be connected to the LISP directory, or have write access
to it.)
llsernamelst is a list of elements of the form (username firstname T . forms),
e. g.,
(TE ITELMAN WARREN T (CHANGESLICE 100) (SETQ DWIMWAIT 5». cadr of the
list is used in the greeting message.
cdddr is a list of forms that are
evaluated.
~sernamelst
can be edited just like any other list, e.g., with editv.
USERNAMEF ILE,
created by makeusernames,
The file
contains usernamelst along wi th an
index block which contains for each user on usernamelst the address in the file
80--~~~~-~~~~~~~--;~~-~;--;:;;;;;s~-i-~;-~:~~~~~--;;;-~;~;;~i;-~;~:~~~:;--;;-~i~
(initially T). Alternatively, sysoutgag can be a list, in which case it is
evaluated (if the user names are different), and thus the user can print
his own message.
22.65
(i.e .. byte position) of the start of his entry.
greet then simply does an
sfptr and a read.
If usernamelst contains an ele'ment for which the username is NIL,
i.e..
an
e lemen t of the form (NIL . forRls). this is interpreted to mean that forms are
evaluated regardless of user name.
This feature can be used to "patch" an
INTERLISP system when a bug is found, or to change some default for INTERLISP'
at
a
particular
site,
e.g.,
turn
off
DWIH,
perform
lowercase[T],
etc.
,
Individual user initialization will still be performed following this system
initialization.
22.66
Index for Section 22
Page
Numbers
AOOSTATS[STATLST] NL* .....•..................••.
AFTER (prog. asst. command) .....•...............
ALL PROP .......................•••••...•.........
ALREADY UNDONE (typed by system) •.......•...•...
AND (in event specification) .•...••..••..•••.••.
AND (in USE command) .......•....••.•...•...•..••
ARCH IVE (prog. asst. command) ...••.•..••..••..••
ARCHIVEFN (prog. asst. variable/parameter) .•...•
ARCHIVELST (prog. asst. variable/parameter)
backtracking
................................... .
BEFORE (prog. ass t. command) •.•.•.•••••..•.•••.•
boll (in history event) ......•.•..••..••••••.•..
BLKLIBRARYOEF (property name) ...••••••.•...••.••
CtI ANG[S LIe E[ N; HIS TOR Y; L] ......•.••...•••.....•.•
CLEARBUF[FILE;FLG] SUBR ...••..•..••..•.•...•...•
CONTIN (prog. asst. command) ....•••...•..•.•.•..
CONTINUE SAVING? (typed by system) ••.•.•••.•..•.
con t r 0 1 - 0
control-E
control-U
.". . • • • • '. . . . . • . .. . • • • • • • • • • • • • • • • • • • • • . •
.................................. *' • • • •
...................................... .
DFNFLG (system variable/parameter) •.••••.•.••••.
oIR (prog. ass t. command) .•••.••••.•.••••..•..•.
DO (edit conunand) .........•..•..••••••••.•..••••
00 (prog. asst. conunand) .....•..••••.•••.•••....
OW 1M
..............
It
...............................
.
DWIMWAIT (dwim variable/parameter) ••..•••.••••••
E (edit command) ....••..•.•..•••.•••.••.••..••••
EDITDEFAULT
.•..••••••.•••.•••••.•••••••••••••.••
EDITHISTORY (editor variable/parameter) .••....••
ENTRYI[HISTiX] .............• ~ ••••••.•••••.•..•..
ERROR (property name) .......•••.••••••••••...•••
ESUBST[X;Y;Z;ERRORFLG;CHARFlG] •••••...••..•.••.•
ovent address ........•..•••..•••..••.•••.•..•...
even t number .............••..•••..••.•••.•.•••••
event specification ........•.••..•••.•.•...•.•..
EXEC (prog. asst. command) ..••••••.•.•••.....•.•
F (in event address) ......•••.•.••••.•••.••••...
F I X (prog. asst. command) .....•.•.••..•..•.•.•..
FOR (in USE command) ........•••.••.•.•.••.•..•..
FORGE T (prog. ass t. command) .•••••..••.••.....•.
format and use of history list .......•...•.•...•
FROM (in event specification) ..•..••......••....
GREET[NAME;FLG] ...................•..•..•..•.••.
greeting and user initialization •..•...•••..•••.
GROUP (pro~erty na~e) .........•......•..•..••.•.
HElPCLOCK (system variable/parameter) .......... .
HISTORY (property name) ..•...••..•.....••..•••..
h is tory commands ..........................•.....
history commands applied to history commands
history commands that fail ...••....•........•..•
history list .................................... .
HISTORYCOMS (editor variable/parameter) ........ .
HISTORYFIND ...............•...•...•.............
HISTORYSAVE[HISTORY;IDjINPUTl;INPUT2,INPUT3;PROPS]
implementation of REDO, USE, and FIX .....•.••.•.
IN (i n USE command) .....••••••••••••••••••.•••••
INDEX.22.1
22.63
22.22,26,34
22.55
22.22,59
22.13
22.14
22.27
22.27,33-34
22.44,53
22.60
22.22,26,34
22.22,33,44,49,52
22.57,63
22.8,54
22.30
22.34
22.39,57
22.30
22.30
22.32,50
22.43,55
22.34
22.31,61
22.31
22.23
22.39
22.62
22.61
22.44,49,60-62
22.54
22.24,45
22.14
22.12-13
22.8,12,21,33,54
22.11-14,19-21
22.34
22.12
22.16"'17,22
22.14
,22.27,54
22.44-47
22.13
22.64
22.64
22.45-46,52
22.21,38
22.45-46
22.10-27
22.19
22.20
22.6-14,44
22.61
22.53
22.11,44-46,52,61
22.17-19
22.14
Page
Numbers
IISP (prog. asst. conunand)
..•...............•.••
22.34
lISPX[lISPXX~lISPXID;lISPXXMACROS;LISPXXUSERFN;
LISPXFLG]
...........' ...•................•..
LISPX/[X;fN;VARS] ..........•......•..•..•..•..••
LISPXCOMS (prog. asst. variable/parameter) •.••.•
LISPXEVAL[ LISPXFORM; LISPXIO] ................•..•
LISPXFINO[HISTORY;lINE;TYPE;BACKUP;QUIETFLG]
LISPXtlIS T (prog. asst. varj.able/parameter) .••...
LISPXHISTORY (prog. asst. ,'ariable/parameter)
LISPXtnS TORY (system variable/parameter) .••.••••
LISPXlINE (prog. asst. variable/parameter) ••••.•
LISPXMACROS (prog. asst. variable/parameter)
LISPXPRINT (property name) .....••••...•....•••••
LISPXPRINT[X;Y;Z;NODOFLG] .........•..•........•.
lISPXPRINTFlG (system variable/parameter) ..•••••
LISPXREAD[FIlE] ......••.......•..•.•.•...••.•••.
..........................................
LISPXREADFN (prog. asst. vCllriable/parameter)
LISPXREADP[FLG] .•........•..•.•.••.•..•.••••••••
LISPXSTATS[FLG] ............•..•...•....•.•.....•
LISPXUNREAD[LST] ............•.•..•...••••.••.•..
LISPXUSERFN (prog. asst. variable/parameter)
LISPXWATCH[STAT;N] .......•................•...•.
MAKEUSERNAHES ................•••..••.•...••.•.••
NAME (prog. asst. conunand) ..•.•••••••.•....••.••
NEW IFN[ FN]
..............•..••••••.••...•••••••••
NlSETQ[NLSETX] NL ..........•...••.••...•••.•.••.
NO VALUE SAVED: (error message) .•.•...•.••.••••.
NOBIND
NOS AVE
................•••••.•••••.••..•.••••••••
••••••••••••••••••••••••••••••••••••••••••
NOSUBSTFNS (prog. asst. variable/parameter)
NOTHING SAVED (typed by system) ..•.•..•..••••...
PRINT (property name) .................•.•••...•.
PRINTltISTORY[ HISTORY; LINE :SKIPFN jNOVALUES] •.•...
programmer's assistant ......••.•.•....•.••.••...
programmer's assistant and the editor ..•..•••••.
programmer's assistant commands .•••...•.....••..
prompt character .....•.......•.•.••..•....•••.••
PROMPTIFlG (prog. asst. variable/parameter)
PROM PTCHAR[ I 0 ; FLG; HIS T] . . . . . . . • . . . . . . . . • . . . . . . . .
READBUF (prog. asst. variable/parameter) .•...•••
READLINE[L.INE;LISPXFLG] ......•.••....•••••••.•••
..........................................
REDO (prog. asst. command) .......•..•.•.•••••...
REREAOFLG (prog. asst. variable/parameter) •.••••
RESET (typed by system) ..•..•.•••••..••••••..•.•
restoring input buffers .....••.•.••••.....•..•••
RETRIEVE (prog. asst. command) ••..••.•.•.••.•...
RETRY (prog.· asst. conunand) .•••..••••••..•......
RPAQ[RPAQX;RPAQY] NL ..........••.•••..••........
RPAQQ[X;Y] NL ....................•••.•.••..•••••
SAVESET[NAME;VALUE;TOPFLG:FLG] ...•••.••••..•..••
SIDE (property name) ..............••••••••.•••••
SNOHSG (prog. asst. command) ...•.•••••••.•••••••
SPELLINGS3 (dwim variable/parameter) ••••••••••••
INOEX.22.2
22.10-11,15-16,19-20,29,
34-35,37-38,40-41,
44-49,52,61-62
22.40,58
22.38
22.52
22.53,62
22.45-46,56,59-60
22.44,49,60-61
22.62
22.34
22.34,49
22.38,45
22.37,45
22.38
22.10,19,29,32,47-48,50,
61
22.50
22.50,61
22.63-64
22.51
22.35,37,47,49
22.63
22.65
22.14,22,25-26
22.57
22.59
22.56
22.43,55
22.56-57
22.58
22.22,39
22.45
22.22,37-38,60
22.1-48
22.61
22.10-31
22.10,33,51
22.33,51
22.33,51,61
22.50-51
22.14,19,32,37,47-48,50,
61
22.14,17,22
22.50,52
22.43,55
22.30
22.22,26,34
22.21-22
22.43
22.43
22.40,43,55
22.45-46,56-57,59,61
22.34
22.55
Page
Numbers
statistics
..................................... .
SUBSYS[FILE/FORKjINCOMFIlEjOUTCOMFILE;
ENTRYPOIN1FLG] .............•.•.•......•.•.
SY (prog. asst. command) ..............•..•....•.
SYSOUIGAG (system variable/parameter) .....•..•.•
TECO (prog. ass t. command) ..•....••••.••.••.•.••
TESTMOOE[FlG] ..............................•....
TESTMODEFlG (prog. asst. variable/parameter)
THRU (in event specification) •.•••.•.•••••.•....
time-slice (of history list) ..••••••••••.•...•••
TO (in event specification) ...•..••..•.••....••.
TYPE-AHEAD (prog. asst. command) .•••.•••..••..••
UNOO (prog. asst. command) .•.•...•••.•.••..••••.
UNDO (ed it command) ....•.•.......•..••..........
lJ n (I 0
i. n 9
..•....•..••••••••.••••••••••••••••••••••
undoing (in edi tor) .............••••...•......•.
undoing DWIM corrections .....•••••.•..•.•.•...••
undoing out of order .........•..................
UNDOl ISPX[ LINE] •................•••....•..•.....
UNOOlISPX1[EVENT;FlG;OWIMCHANGES] .•.....•.....••
UNOOLST (editor variable/parameter) ..........•..
UNOONE (typed by sys tern) ....••..•••..•••.•..•...
UNDONLSEIQ[UNDOFORM;UNDOFN] NL ••.••••.••.••..•..
UNOOSAVE[UNOOFORM;HISTENTRY] ..•.••...•.•••.•.•••
unrea{ling
....................................... .
UNSE T[ NAME] ................................••...
USE (prog. ass t. command) ....••..•••....••.••.•.
USE-ARGS (property name) ...............•..•.••..
USfREXEC[lISPXIO;lISPXXMACROS;lISPXXUSERFN]
USERNAME (prog. asst. variable/parameter) ....•••
USfRNAMElST (prog. asst. variable/parameter)
VALUE (property name) ....•.••••.•••..••..•.••.••
VALUEOF[X] NL" ............•••.••.•••..••..•..•.•
!E (prog. asst. command) ..•.•••.••.••.•.....•.•.
!E (edit command) ...........•.•.•........•.....•
!F (prog. asst. command) ....•....••...•.........
! F (c d i t comma n d)
.....................•••.....•..
!N (prog. asst. command) .....•.....•...••.••....
! N (edi t command)
............•.•••.•....•..•••..
#0 (use in history commands) ..............•.....
HUNDOSAVES (prog. asst. variable/parameter)
S (a 1t-mode) (prog. asst. command) ...........•..
SBUFS (alt-modeBUFS) (prog. asst. command) ..... .
••• .... ATTENTION USER -- (typed by system) ....... .
. .. (prog. ass t. command) •...•••••...•.•••......
. .. (typed by sys tem) .......•....••..•...•.•....
I functions
.................................... .
IRPLNODE[X;A;D] .............•.•..•..•.••••...•.•
= (in event address)
.....•...•....••............
?? (prog. ass t . command ) ...••.•..•..............
@ (in event specification)
..•...••.•..••..••....
@@ (in event specification) •••.••.••............
\ (in event address) ....•..••....•.•...••.......
~ (in event address)
..••...•..••.•••.•.•.••••••.
INDEX.22.3
22.63
22.34
22.34
22.65
22.34
22.41
22.41
22.13
22.8,54
22.13
22.28-29
22.13,22-23,43,58,61
22.61
22.5,38,55,62
22.62
22.23
22.23,42
22.58
22.59
22.62
22.22,59
22.59
22.45-46,56
22.10-11,18,51
22.43,56
22.14-15,17,22
22.45
22.49
22.65
22.65-66
22.43,55-56
22.33,46,54
22.31
22.31,61
22.31
22.31,61
22.31
22.31,61
22.18,50-51
22.39,56-57,60
22.23-25
22.30
22.65
22.21-22
22.48
22.40,57-58
22.57
22.12·
22.21-22
22.14,53
22.14,27,53
22.13
22.12
SECTION 23 1
CLISP - CONVERSATIONAL LISP
The syntax of LISP is very simple,
in the sense that it can be described
concisely. but not in the sense that LISP programs are easy to read or write!
This simplicity of syntax is achieved by, and at the expense of, extensive use
of explicit structuring, namely grouping through parenthesesization.
Unlike
many languages, there are no reserved words in LISP such as IF, THEN, AND, OR,
FOR, DO, BEGIN, END, etc., nor reserved characters like +, ., -, /,
~, etc. 2
=,
This eliminates entirely the need for parsers and precedence rules in the LISP
interpreter
and
compiler,
programs straightforward.
and
thereby makes
program
manip~lation
of
LISP
In other words, a program that "looks at" other LISP
programs does not need to incorporate a lot of syntactic information.
For
example, a .LISP interpreter can be written in one or two pages of LISP code
([Meet],
pp.
70-71).
It is for this reason that LISP is by far the most
suitable, and frequently used, progranuning language for writing programs that
deal with other programs as data, e.g., programs that analyze,
construct other
2
modify,
or
pro~~ams.
except for parentheses (and period), which are used
structure, and space and end-of-line, which are used
identifiers.
23.1
for
for
indicating
delimiting
However,
it
is
precisely this same simplicity of syntax that
programs difficult to read and write (especially for beginners).
down' is something programs do vel"y well, and people do poorly.
makes
LISP
'Pushing
As an example,
consider the following two 'equivalent' sentences:
"The rat that the cat that the dog that I owned chased caught ate the
cheese."
versus
It I
own the dog that chased the cat that caught the rat that ate the
cheese."
Natural language contains many linguistic devices such as that illustrated in·
the second sentence above for minimizing embedding, because embedded sentences
are more di ffi cuI t to grasp and understand than equivalent non-embedded ones
(even if the latter sentences are somewhat longer).
Similarly, most high level
programming languages offer syntactic devices for reducing apparent depth and
complexity of a program: the reserved words and infix operators used in ALGOLlike languages simultaneously delimit operands and operations, and also convey
meaning to the programmer.
They are far more intuitive than parentheses.
In
fact. since LISP uses parentheses (i.e. lists) for almost all syntactic forms,
there is vory little information contained in the parentheses for the person
reading a LISP program, and so the parentheses tend mostly to be ignored: the
meaning of a particular LISP expression for people is found almost entirely in
the words, not in the structure.
For example, the following expression
(COND (EQ N 0) 1) (T TIMES N FACTORIAL «SUBl N»)
is recognizable as FACTORIAL evenl though there are five misplaced or missing
parentheses.
Grouping words together in parentheses is done more for LISP's
benefi t, than for the programmer IS,.
CLISP is designed to make INTERLISP programs easier to read and write by
23.2
permitting the user to employ various infix operators, If-THEN-ELSE statements,
FOR-DO-WHILE-UNLESS-FROM-TO-etc. expressions, which are automatically converted
to
equivalent
INTERLISP expressions when
they are
first
interpreted.
For
example, FACTORIAL could be written in CLISP:
(IF N=O THEN 1 ELSE N*(FACTORIAL N-l»
Note that this expression would become a,n equivalent CONO after it had been
interpreted once,
so that programs that might have to analyze or otherwise
process this expression could take advantage of the simple syntax.
There have been similar efforts in other LISP systems, most notably the MLISP
language at Stanford [Smit].
CLISP differs from these in that
attempt to replace the LISP syntax so much as to augment it.
it does not
In fact, one of
the principal criteria in the design of CLISP was that users be able to freely
intermix LISP and CLISP without having to identify which is which.
write programs,
or type in expressions for evaluation, . in LISP,
mixture of both.
Users can
CLISP,
or a
In this way, users do not have to learn a whole new language
and syntax in order to be able to use selected facilities of CLISP when and
where they find them useful.
CLISP
is
Boction
implemented via
17).
Thus,
the error correction machinery
any
expression
that
is
in
well-formed
INTERLISP
from
(see
INTERLISP's
standpoint will never be seen by CLISP (i.e., if the user defined a function
IF.
he
would
interpreted
effectively
programs
turn
off
that
form
• know' about CLISP at all.
is
invokes
encountered,
the
expression
the
This
question
In fact. the
INT~RLISP
means
pay
for
that
its
interpreter does
It operates as before, and when an erroneous
interpreter calls an error routine which
Do-What-I-Mean
in
of CLISP).
that do not use CLISP constructs do not
availability by slower execution time.
not
part
(DWIM)
turns out
analyzer which
contains
to be a CLISP construct,
23.3
CLISP.
tho
in
If
turn
the
equivalent
INTERLISP form is returned to the interpreter. In addition, the original CLISP
expression, is modified so that it becomes the correctly translated INTERLISP
form.
In this way, the analysis and translation are done only once.
Integrating
CLISP
implementing
features
into
the
INTERLISP
system
(instead
of,
it as a separate preprocessor) makes possible
for
example,
Do-What-I-Mean
for CLISP constructs as well as for pure LISP expressions.
for
example, if the user has defined a function named GET-PARENT, CLISP would know
not
to attempt to interpret the form (GET-PARENT) as an arithmetic
operation.
infix
(Actually, CLISP would never get to see this form, since it does
not contain any errors.)
If 'the user mistakenly writes (GET-PRAENT), CLISP
would know he meant (GET-PARENT), and not (DIFFERENCE GET PRAENT), by using the
information that PRAENT is not the name of a variable, and that GET-PARENT is
the
name
of
a
user function
whose spelling is
"very close"
to
that
of
GET-PRAENT. Similarly, by using information about the program's environment not
readily
available
to
a
preprocessor,
CLISP can
successfully
resolve
the
following sorts of ambiguities:
1)
(LIST X-FACT N),
where
FACT
is
the
name
of
a
variable,
means
(LIST (X-FACT) N).
2)
(LIST X*FACT N), where FACT is not the name of a variable but instead is
the
name
of
a
function,
(LIST X*(FACT N»,
means
i.e.,
N is
FACT's
argument.
3)
(LIST X*FACT(N»,
FACT the name of a function (and not the name of a
variable), means (LIST X*(FACT N».
4)
cases (1),(2) and (3) with FACT misspelled!
The first expression is correct both from the standpoint of CLISP syntax and
23.4
senlantics and the change would be made without the user being notified.
In the
other cases,
the user would be informed or consul ted about what was taking
place.
example,
For
to
take
an
extreme
case,
suppose
the
expression,
(LIST X*FCCT N) were encountered, where there was both a function named FACT
and
a
variable
named FCT.
misspelling of FCT.
(LIST (X*FCT) N).8
The
user would· first
If he said YES,
If he said NO,
be
asked
if FCCT
were
the expression would be interpreted as
the user would be asked if FCCT were
misspelling of FACT, i.e., if he intended X*FCCT N to mean X*(FACT N).
since
FCCT
a
If he
said YES to this Question, the indicated transformation would be performed.
he said NO,
a
If
the system would then ask if X*FCCT should be treated as CLISP,
is
not
expression would
be
the name
of a
transformed,
(bound)
if NO,
variable. 4
it would be
If he
said
left alone,
YES,
i.e.,
the
as
(LIST X*FCCT N). Note that we have not even considered the case where X*FCCT is
itself a misspelling of a variable name, e.g., a variable named XFCT (as with
GET-PRAENT).
This sort of transformation would be considered after the user
said NO to X-FCCT N -) X*(FACT N). The graph of the possible interpretations
for (LIST X*FCCT N) where FCT and XFCT are the names of variables, and FACT is
the name of a function, is shown in Figure 23-1 below.
a----------------------------------------------------------------------------Through th is discussion, we speak of CLISP or DWIM ask.ing the user.
Actually, if the expression in question was typed in by the user for
immediate execution, the user is simply informed of the transformation, on
the grounds that the user would prefer an occasional misinterpretation
rather than being continuously bothered, especially since he can always
retype what he intended if a mistake occurs, and ask the pronrammer I s
assistant to UNDO the effects of the mistaken operations if necessary. For
trallsformations on expressions in user programs, the user can inform CLISP
whether he wishes to operate in CAUTIOUS or TRUSTING mode.
In the former
case (most typical) the user will be asked to approve transformations, in
the latter, CLISP will operate as it does on type-in, i.e., perform the
transformation after informing the user.
4
This question is important because many INTERLISP users already have
pronrams that employ identifiers containing CLISP operators.
Thus, if
CLISP encounters the expression AlB in a context where either A or Bare
not the names of variables, it will ask. the user if AlB is intended to be
CLISP, in case the user really does have a free variable named AlB.
23.5
FCCT-
>FCT ?
FCCT N -
2
>(FACT
N)?
X* FCCT-
>XFCT
X*FCCT TREAT AS CLISP?
4
FIGURE
23.6
23-1
5
The final states for the various terminal nodes shown in the graph are:
1:
(LIST (TIMES X FCT) N)
2:
(LIST (TIMES X (FACT N»)
3:
(LIST XFCT N)
4:
(LIST (TIMES X FCCT) N)
5:
(LIST X*FCCT N)
CL ISP can also handle parentheses errors caused by typing 8 or 9 for
, )' .
•)"
f
(f
or
(On most terminals, 8 and 9 are the lower case characters for '(' and
i . e .,
• ('
and
'8 t
appear on the same key, as do
if the user writes N*8FACTORIAL N-l,
example,
detected and fixed before the infix operator
function TIMES.
*
')'
and
'9'.)
For
the parentheses error can be
is converted to the INTERLISP
CLISP is able to distinguish this situation from cases like
N*8*X meaning (TIMES N 8 X), or N*8X, where 8X is the name of a variable, again
by
using
information
about
integrating CLISP with DWIM,
errors
that
the
programming
environment.
In
fact,
by
CLISP has been made sufficiently tolerant of
almost everything can be' misspelled!
For example,
CL ISP
can
successfully translate the definition of FACTORIAL:
(IFF N=O THENNI ESlE N*8FACTTORIAlNN-l)
to the corresponding COND, while making 5 spelling corrections and fixing the
parenthesis error. 6
This sort of robustness prevails throughout CLISP.
For example, the iterative
5'-----------------------------------------------------------------------------CLISP also contains a facility for converting from INTERLISP back to CLISP,
so that after running the above incorrect definition of FACTORIAL, the user
could
I CLISPIFY'
the
now
correct
LISP
version
to
obtain
(IF N=O THEN 1 ELSE N*(FACTORIAl N-l».
23.7
statement permits the user to' say things like: 6
FOR OLD X FROM M TO N DO (PRINT X) WHILE (PRIMEP X)
However, the user can also write OLD
(X~M),
(OLD
(OLD
X~M).
order of the operators, e.g., DO PRINT X TO N FOR OLD
X~H
permute the
(X~M»,
WHILE PRIMEP X, omit
either or both sets of parentheses, misspell any or all of the operators FOR,
OLD,
FROM,
TO, 00, or WHILE, or leave out the word DO entirely!
And,
of
course, he can also misspell PRINT, PRIMEP, H or N!7
CLISP is well integrated into the INTERLISP system.
For example, the above
iterative statoment translates into an equivalent INTERLISP form using PROG,
CONO,
GO,
etc. 8
When
the
interpreter
subsequently encounters
this
CLISP
expression, it automatically obtains and evaluates the translation. 9 Similarly,
the compi ler "knows" to compile the translated form.
PRETTYPRINTs
his
program,
at
the
corresponding
PRETTYPRINT "knows" to print the original CLISP.
However,
point
in
if the user
his
function,
Similarly. when the user
edits his program, the editor keeps the translation invisible to the user.
If
6---~~~~--~~~;~~~~~~--;~~~~~--~;·--;;ii-~-;p;:~:~~~~.--~~~~~~--~~~~~~i~--;~;--~~;
operator OLD, which says X is to be the variable of iteration, i.e., the
one to be stepped from N to M, but X is not to be rebound. Thus when this
loop finishes execution, X will be equal to N+J.
7
8
In this example, the only thing the user could not misspell is the first X,
since it specifies the name of the variable of iteration. The other two
instances of X could be misspelled.
, (PROG NIL
(SETQ X M)
SSlP(CONO
«OR (IGREATERP X N)
(NOT (PRIMEP X»)
(RETURN»)
(PRINT X)
(SETQ X (AODI X»
(GO SSLP»
9
See page 23.30, for discussion of how translations are stored.
23.8
the user modifies the CLISP, the translation is automatically discarded and
recomputed the next time the expression is evaluated.
In short, CLISP is not a language at all, but rather a system.
ilnalagous
to
It plays a role
that of the programmer's assistant (Section 22).
Whereas
the
programmer' s assistant is an invisible intermediary agent between the user' s
(:onsole requests and the INTERLISP executive, CLISP sits between the user's
programs and the INTERLISP interpreter.
Only a small effort has been devoted to defining the core syntax of CLISP.
Instead, most of the effort has been concentrated on providing a facility which
'makes sense' out of the input expressions using context information as well as
built-in and acquired information about user and system programs.
It has been
said t.hat communication is based on the intention of the speaker to produce an
effect in the recipient.
CLISP operates under the assumption that what the
user said was intended to represent a meaningful operation, and therefore tries
very hard to make sense ou t of it.
The moti vat ion beh ind CL I SP is not to
provide the user with many different ways of saying the same thing,
but to
enable him to worry less about the slIntactic aspects of his cOrIUnunication with
the sys tern.
In other words,
it
gives the user a' new degree of freedom by
permitting him to concentrate more on the problem at hand,
rather than on
translation into a formal and unambiguous language.
23.2
CLISP
~~I~.tax
Throughout CLISP, a non-atomic form,
for
a
variable,
example,
and vice versa,
i.e., a list, can always be substituted
without changing
the
interpretation.
For
a,
then
if the value of (FOO X) is A, and the value of (FIE Y) is
(LIST (FOO X)+(FIE
V»~
has the same value as (LIST A+8).
expression consists of a list of Jour elements:
23.9
Note that the first
the atom
'LIST'. the list
'(FOO X)'. the atom '+'. and the list '(FIE X)', whereas the second expression,
(LIST A+B), consists of a list of only two elements: the atom 'LIST' and the
atom
Since
'A+B' .
(LIST (FOO X)+(FIE
(LIS T (FOO X) + (F IE Y»
V»~
indistinguishable
is
from
because spaces before or after parentheses have no
effect on the INTERLISP READ program,10 to be consistent, extra spaces have no
effect
on
atomic
operands
either.
In
other
words,
CLISP
will
treat
(LIST A+_B), (LIST A_+B), and (LIST A_+_B) the same as (LIST A+B).
23.3
Infix Operators
CLISP recognizes the arithmetic infix operators +, -, *, I, and
converted to
IPLUS,
t.
These are
IDIFFERENCE (or in the case of unary minus,
IMINUS),
ITIMES, IQUOTIENT, and EXPT. ll The usual precedence rules apply (although these
can be easily changed by the user),12 i.e., * has higher precedence than + so
that A+B*C is the same as A+(B*C), and both * and I are lower than
t
so that
2*Xt2 is the same as 2*(Xt2). Operators of the same precedence group from left
to
right,
e. g..
AlBIC
is equl.valent to (AlB) IC.
Minus is binary whenever
possible, i.e., except when it is the first operator in a list, as in (-A) or
(-A), or when it immediately follows another operator, as in A*_B. la 14
------------------------------------------------------------------------------10
CLISP does not use its own special READ program because this would require
the user to explicitly identify CLISP expressions, instead of being able to
intermix INTERLISP and CLISP.
11
The I in IPLUS denotes integer arithmetic, i.e., IPLUS converts its·
arguments to integers, and returns an integer value.
INTERLISP also
cont.ains floating point arithmetic functions as well as mixed arithmetic
functions (seo Section 13). CLISP contains a facility for declaring which
type of arithmetic is to be used, either by making a global declaration, or
by separate declarations about individual functions or variables.
See
section on declarations, page 23.33.
12
The complete order of precedence
Figure 23-2, page 23.15.
13
There are some do-what-I-mean features associated with Unary minus, as 1n
(LIST -X V). See section on operation, page 23.64.
23.10
for
CLISP
operators
is
given
in
Note that grouping fuith parentheses can always be used to override the normal
precedence grouping. or when the user is not sure how a particular expression
lui il parse.
(LISP also recognizes as infix operators
=.
GT, IT. GE, and lE,15 as well as
various predicates, e.g., MEMBER, AND, OR, EQUAL, etc. t6 AND is higher than OR,
B • g.,
(X
OR Y AND Z) is the same as (X OR (Y AND Z», and both AND and OR are
lower than the other infix operators, e. g., (X AND Y EQUAL Z) is the same as
(X AND (Y EQUAL
INTERLISP forms,
Z».
All of the infix predicates have lower precedence than
i.e., (FOO X GT FIE Y) is the same as «FOO X) GT (FIE
V»~,
since it is far more common to apply a predicate to two forms, than to use a
Boolean
as
an argument
to a function,
e.g.
(FOO (X GT (FIE Y»).
However.
again, the user can easily change this.
Note that only single character operators, e,g. +, ~, =, etc., can appear in
the interior of an atom. All other operators must be set off f1~ identifiers
loith spaces. For example. XlTY will not be recognized as CLISP.
14----------------------------------------------------------------------------Note that + in front of a number will disappear when the number is read,
e.g .•
(rOO x +2) is indistinguishable from (FOO X 2).
This means that
(FOO X +2)
will not be interpreted as CLISP, or be converted to
(FOO (IPLUS X 2», Similarly, (FOO X -2) will not be interpreted the same
as (FOO X-2). To circumvent this, always type a space between the + or and a number if an infix operator is intended, e.g., write (FOO X + 2).
15
Greater Th~n, Less Than, Greater than or Equal to, and Less than or Equal
to, resjlccti ve-ly. GT. LT. GE, and LE -are all affected by the -'same
doclar~ations as + and *, with the initial default to use IGREATERP and
ILESSP.
16
Currently the complete list is MEMBER, MEMB, FMEMB, IlESSP, IGREATERP,
lESSP, GRfATERP, FGTP, EQ, NEQ, EQP, EQUAL, OR, and AND.
New infix
operators can be easily added. as described in the section on CLISP
internal conventions, page 23.68.
17
In some cases, OWH1 will be able to diagnose this situation as a run-on
spoIling error, in which case after the atom is split apart, CLISP will be
able to perform the indicated transformation.
23.11
*
*
is an infix operator used in CLISP for extracting substructures from lists,18
e.g., X:3 specifies .the 3rd element of X, (FOO Y)::Z spe~ifies the second tail
of (FOO V), i.e., (CDDR (FOO
V»~,
and Z:l:Z is the second element of the first
element of Z, or (CADAR Z).
Negative numbers may be used to indicate position
counting from the end of a li.st, e.g., X:-l is the last element of X,
or
(CAR (LAST X», X::-l is the last tail, i.e., (LAST X).19
*
~ is used to indicate assignment, e.g., X~Y translates to (SETQ X y).20 21 In
conjunction with: and ::,
~
can also be used to perform a more general type of
assignment, namely one involving structure modification.
means
make
the
second
element
of
X
be
Y,
in
For example,
INTERLISP
X:2~Y
terms
18------------------------------'----------------------------------------------The rncord facility, page 23.48, provides another way of extracting
substructures by allowing the user to assign names to the various parts of
the structure and then retrieve from or s tore into the corresponding
structure by name. The pattern match facility, page 23.36, also can be
used to extract substructure. : is also used to indicate both record and
pattern match operations.
19
The interpretation of negative numbers can be explained neatly in terms of
edi t conunands: : -n returns what would be the current expression after
execu t i ng the command -n. and :: -n returns what wou Id be the current
expression after executing -n followed by UP.
20
I f x does not have a value, and is not the name of one of the bound
variables of the function in which it appears, spelling correction is
attempted.
However, since this may simply be a case of assigning an
initial value to a new frelB variable, DWIM will always ask for approval
before making the correction.
21
Note that an atom of the form X~Y. appearing at the top level of a PROG,
not be recognized as an assignment statement because it will be
interpreted as a PROG label by the INTERLISP interpreter,and therefore
will not cause an error, so DWIM and CLISP will never get to see it.
Instead, one must write (X~Y).
wi 11
23.12
(RPlACA (CDR X) y).22 23 Negative numbers can also be used, e.g., X:_2~y.24 ~
is also used to indicate assignment in record operations,
page 23.48,
ftnd
pattern match operations, page 23.36 .
... has di fferent precedence on the left from on the right.
"tight" operator, i.e., high precedence, so that
On the right, .. has broader scope so that
On
typein,
$~form
men t ioned" . 26
For
(alt-mode~form)
example,
is
A~B+C
A+B~C
is the same as
is the same as
equivalent
inunediate1y
On the left, .. is a
after
to
set
A+(B~C).
A~(B+C).
the
examining
the
"last
thing
value
of
LONGVARIABlENAME, the user could set it by typing $.. followed by a form.
Prefix Operators
23.4
CLISP recognizes • and - as prefix operators.
first
character in an
identifier,
interior of an identifier.
Thus,
t
means QUOTE when it is the
and is ignored when it is used
X='Y means
(EQ X (OUOT£
means (EQ X CAN'T), not (EQ X CAN) followed by (QUOTE T).
V»~,
in the
but X=CAN'T
This enables users
to have variable and function names with ' in them (so long as the • is not the
first character).
-------------------------------------------------------------------------------Noto that the value of this operation is the value of rplaca, which is the
2~~
corresponding node.
23
The user can indicate he wants Irplaca and Irplacd used (undoable version
of [Qlafa and [pIacd, see Section 22), or frplaca and frplacd (fast
versions of rplaca and rplacd, see Section 5), by means of declarations
(page 23.33). The initial default is for rplaca and rplacd.
24
which translates to (RPlACA (NlEFT X 2) V).
26
i.e. is equivalent to (SETQ lastword form). See Section 17.
23.13
Following
all operators are ignored for the rest of the identifier, e.g.,
I
'*A moans (QUOTE *A), and IX=Y means (QUOTE X=Y), not (EQ (QUOTE X) y).20
On typein,
1$
Section 17).
(i.e. 'alt-mode) is equivalent to (QUOTE value-of-lastword) (see
For example, after calling prettyprint on LONGFUNCTION, the user
could move its definition to FOO by typing (NOVO 'S 'FOO).27
..... means NOT.
-
can negate a form, as in -(ASSOC X Y), or -X, or negate an
infix operator, e.g., (A -GT
a)
1s the same as (A LEQ
a).
Note that
-A=a
means
(EQ (NOT A) B).
--------------------------------------.---~----------------------------~-~----26
To write (EQ (QUOTE X) V). one writes V=IX, or 'X_=V. This is one place
where an extra space does make a difference.
27
(MOVO $ 'FOO),. which would be equivalent to (MOVO LONGFUNCTION 'FOO),
and would (probably) cause a U.B.A. LONGFUNCTION error, nor MOVO(S FOO),
which would actually move the definition of S to FOO, since DWIM and the
spelling corrector would never be invoked.
Not
23.14
Order of Precedence of CLISP operators
~
(left precedence)
28
29
- (unary) • ...,
t
", I
... , ~
(binar~y)
(right precedence)
::
INTERLISP forms
LT, GT, EQUAL, MEMBER, etc.
AND
OR
IF, THEN, ELSEIF, ELSE
iterative statement operators
Figure 23-2
28--:-~~~-~-~~-;;e~~~~--1;i;-~~~-~~~h;-;;;~;~;~~;:-~~~~~-~:~~c:~--;;-;~;-;;~~-~;
In other words,
scope on the right.
A+(U~(C+D».
~
has minimal scope on the left and maximal
-=,
When - negates an operator, e.g.,
-LT, the two operators are treated as
a single operator whose precedence is that of the second operator. Whennoga tes a function. e. g., (-FOO X Y) ~ it negates the whole form, 1. e. ,
(-( FOO X Y».
23.15
Constructing Lists - the <,) operators 30
23.~
Angle brackets are used in CLISP to indicate list construction.
The appearance
of a '(I corresponds to a Ie' and indicates that a list is to be constructed
containing all the elements up to the corresponding ')'. for example, (A B (e»
translates to (LIST A B (LIST C».
expression
is
to be
inserted in
translates to (CONS A (CONS B C)
! can be used to indicate that the next
the
list as a segment,
e.g.,
e>
(A B
and (! A ! B C) to (APPEND A B (LIST'C».
!!
is used to indicate that the next expression is to be inserted as a segment,
and furthermore, all list structure to its right in the angle brackets is to be
physically attached to it,
e.g.,
need not
be
separate atoms,
for exampl,e,
which translates to
(CONS (SETQ Faa (FIE X»
~pend,
using
V).
CLISPIFY
converts expressions
in
~,
list,
nconc, nconc1, !nconc, and !nconc1 into equivalent CLISP expressions
<, >,
!, and !t.
Note: angle brackets differ from other CLISP operators in that they act more
like
brackets
than
(LIST A 8 (QUOTE C»
31
32
operators.
for
example,
(A B 'C)
translates
to
even though following " all operators are ignored for the
Not (NCONC (APPEND A B) C), which would have the same value,
attach C to Bf and not attach either to A.
but would
The user can indicate !nconc or !nconc1 be used instead of
and nconcl
by declarations.
23.16
ll£QQ£
rest
of
the
identifier:33 Note however that (A B '_C> D)
(LIST A B (QUOTE C»
i$
equivalent
to
0).
IF, THEN, ELSE
23.6
CLISP
translates
c:ondi tional
expressions
expressions.
IFITHENIELSEIFIELSE
employing
The segment
between
into
equivalent
IF I ELSEIF and the next THEN
corresponds to the predicate of a COND clause, and the segment between THEN and
the next ELSEIELSEIF as the consequent(s).
ELSE is the same as ELSElf T THEN.
IF, THEN, ELSE, and· ELSEIF are of lower precedence than all infix and prefix
operators,
as well as
INTERLISP forms,
betweon IFIELSEIF, and THEN.
so that parentheses can be omitted
For example, (IF FOO X Y THEN --) is equivalent
to (IF (FOO X Y) THEN __ ).34 Simi larly , CL ISP treats (IF X THEN FOO X Y ELSE
-,-) as equivalent to (IF X THEN (FOO X Y) ELSE --) because it does not
sense'
also
to evaluate a variable for effect.
the
E.ssen tiaIly,
name
of
a
variable,
'make
In other words, even if FOO were
(COND (X FOO X
V»~
doesn't
make
sense.
CL ISP determines whether the segment between THEN and the next
ELSEIELSEIF corresponds to one form or several and acts accordingly.36 Thus,
(IF -- THEN (FOO X) Y ELSE --) corresponds to a clause with two consequents.
Similarly,
34
(IF -- THEN
FO~X
Y ELSE --)
corresponds
to
a
clause
with
two
FOO is the name of a variable, IF FOO THEN -- is translated as
(COND (FOO --»
even if FOO is also the name of a function.
If the
functional
interpretation is intended,
FOO should be ene losed in
parentheses, e.g., IF (FOO) THEN --. Similary for IF -- THEN FOO ELSElf
If
occasionally interacting with the user to resolve ambiguous cases.
23.17
consequents, and is equivalent ,to (IF -- THEN (FOo.-X) Y ELSE __ ).80
Iterative Statements
23.7
The following is an example of a CLISP iterative statement:
(WHILE X"(REAI»-='STOP DO (PRINT (EVAL X»)
This statement says "READ an expression and set X to it.
If X is not equal to
the atom STOP, then evaluate X, print the result, and iterate."a7
The i.s. (iterative statement) in its various forms permits the user to specify
complicated
Rather
than
iterative
the
statements
in a straightforward and visible manner.
user having to perform the mental
transformations
to
an
equivalent INTERLISP form using PROG, MAPC, MAPCAR, etc., the system does it
for him.
The goal was to provide a robust and tolerant facility which could
"make sense" out of a wide clilss of iterative statements.
Ac'cordingly, the
user should not feel obliged to read and understand in detail the description
of each operator given below in order to usc iterative statements.
Currently, the following i. s. operators are implemented: FOR, BIND, OLD, IN,
ON, FROM, TO, BY, WHEN, WHILE, UNTIL, UNLESS, COLLECT, JOIN, 00, SUM, COUNT,
ALWAYS,
NEVER,
THEREIS,
AS,
FIRST,
FINALLY,
EACHTIME.
Their
function
is
36----------------------------------------------------------------------------To write the equivalent of a singleton cond clause, i.e., a clause with a
predicate but no consequent, write either nothing following the THEN, or
omit
the
THEN
entirely,
e.g.,
(IF (FOO X) THEN ELSEIF --)
or
(IF (FOO X) ELSEIF --), meaning if (FOO X) is not NIL, it is the value of
tho condo
37
Tho statement translates to:
(PROG NIL SSLP (COND «EQ (SETQ X (READ»
(PRINT (EVAL X» (GO SSLP»
23.18
(QUOTE STOP»
(RETURN»)
explained below.
Misspellings
of
New operators can be defined as described on page 23.28.
operators
are
recognized
and
corrected.
The
order
of
appearance of operators is not impo~tant;38 CLISP scans the entire statement
before it begins to construct the equivalent INTERLISP form.
00 form
specifies what is to be done at each iteration.
other operator specifies an infinite loop.
00 with no
If some explicit
or implicit terminating condition is specified, the value of
the
i.s.
is
NIL.
Translate
to
MAPC
or
MAP
whenever
possible.
COLLECT form
like DO, except specifies that the value of form at each
iteration is to be collected in a list, which is returned as
the value of the i.s. when it terminates.
Translates to
HAPCAR or HAPLIST whenever possible.
J!OIN form
SUM
form
like 00, except that the values are NCONCed.
HAPCONC or HAPCON whenever Possible. 39
Translates to
like 00, except specifies that the values of form at each
iteration be added together and returned as the value of the
i.s.,
e.g.
(FOR I FROM 1 TO 5 SUH 1'2)
is
equal
to
1+4+9+16+25. 40
38---------------'-------------------------------------------------------------nWIM and CLISP are invoked on iterative statements because car of the i.s.
is not tho namo of a function, and hence generates an erro~ If the user
defines il function by the sarno name as an i.s. operator, e.g. WHILE, TO,
etc., the operator will no longer have the CLISP interpretation when it
appears as car of a form, al though it will continue to be treated as an
i.s. operator if it appears in the interior of an i.s.
39
INCONC, IHAPCONC, and IHAPCON are used when the declaration UNOOABLE is in
effect.
40
iplus, fplus, or ,Rlus will be used for the translation depending on the
declarations in effect.
23.19
COUNT pred
1 ike DO, except counts number of times that pred is true,
and returns that count as its value.
ALWAYS pred
like DO, except returns T if the value of pred is non-NIL
for all i terclltions (returns NIL as soon as the value of pr'ed
is NIL), e.g.
(FOR X IN Y ALWAYS (ATOM X»
is the same as
(EVERY Y (FUNCTION ATOM».
like ALWAYS, except returns T if the value of pred is neuer
NEVER pred
true, i.e. NEVER pred is the same as ALWAYS -pred.
THEREIS pred
returns
the first value of the
non - NIL,
first
e . ~l •
number
i.v.
for which
(FOR X IN Y THEREIS NUMBERP)
in
v,
is
and
pred
returns
equivalent
is
the
to
(CAR (SOME Y (FUNCTION NUMBERP»).41
00.
COLLECT, JOIN, SUM, ALWAYS, NEVER, and THEREIS are ,examples of a certain
kind of i.s. operator called an i.s.type.
done at each iteration.
function
i.s.type,
page
The i.s.type specifies what is to be
Each i.s. must have one and only one i.s.type.
Z3.~8,
provides
a
means
of
defining
The
additional
i.s.types.
FOR var
specifies the. variable of iteration, or i.v., which is used
in conjunction with IN, ON, FROM, TO, and BY.
The variable
is rebound for the scope of the i.s., except when modified
by
OLD as described below.
41----------------------------------------------------------------------------THEREIS returns the i.v. instead of the tail (as does the function some) in
order to provide an interpretation consistent with statements such as
(FOR I FROM 1 TO 10 THEREIS _a), whore there is no tail.
Note that
(SOME Y (FUNCTION NUMBERP» is equivalent to
(FOR X ON Y THEREIS (NUMBERP (CAR X»).
23.20
FOR vars
vars a list of variables, e.g., FOR (X Y 1) IN --. The first
variab Ie is the i. v.,
the rest are dununy var iab les .
See
BIND below.
OLD var
indicates
not
is
e. g. ,
rebound,
be
to
(FOR OLD X FROM 1 TO N DO -- UNTIL --),
BIND var. vars
used to specify dummy variables, e.g., FOR (X Y 1) IN
equivalent
FOR X BIND (Y 1) IN --.
to
without FOR.
can
be
used
For example, in the i.s. shown on page 23.18,
could
X
BIND
is
be
(BIND X WHILE
made
X~(READ)-='STOP
local
by
wri ting
... ).
Note:
FOR, OLD, and BIND variables can be initialized by using ... , e.g.,
(FOR OLD
(X~form)
IN form
BIND
(Y~form)
... ).
specifies that the i.s. is to iterate down a list with the
i.v.
being
reset
iteration.
(HAPC
Y
for
to
the
element
at
each
FOR X IN Y DO -- corresponds
example,
(FUNCTION -(LAMBDA
corresponding
(X)
--»).
If no i.v.
to
has been
specified, a dummy is supplied, e.g., IN Y COLLECT CADR is
equivalent to (MAPCAR Y (FUNCTION CADR».
ON
forom
same
as
IN
except
that
the
i. v.
corresponding tail at each iteration.
is
reset
to
the
Thus IN corresponds
to HAPC, MAPCAR, and HAPCONe, while ON corresponds to MAP,
MAPLIST, and HAPCON.
IN OLD var
specifies that the i.s. is to iterate down var:. with var
itself
being
iteration,
reset
e.g.,
to
after
the
corresponding
tail
each
(FOR X IN OLD L 00 -- UNTIL --)
finishes, L will be some tail of its original value.
23.21
at
IN OLD (var .. form)
same as IN OLD Y!!.!:. except var is first set to value of
form.
ON
OLD var
same as IN OLD var except tho i. v. is reset to the current
value of var at each iteration, instead of to car[var].
ON
OLD (var .. form)
same as ON OLD
Y!!:,.
except Y!!: is first set to value of
form.
WHEN pred
provides
a
way
of
excepting
certain
iterations.
For
example, (FOR X IN V COLLECT X WHEN NUMBERP X) collects only
the elements of Y that are numbers.
UNLESS pred
same as WHEN except for the difference in Sign, i.e., WHEN Z
is the same as UNLESS -Z.
WHILE pred
WHILE pred evaluates
provides a way of terminating the i.s.
pred before each iteration, and if the value is NIL, exits.
UNTIL pred
Same
as
WHILE
except
for
difference
in
sign,
i. e. ,
WHILE PRED is equivalent to UNTIL -PRED.
UNTIL n
n a number, equivalent to UNTIL (i.v. GT n).
FROM form
is used to specify an ini tial value for a numerical i. v.
The
i.v.
is
automatically
incremented
iteration
(unless BV is specified).
specified,
a
by
If no
1
after
i.v.
each
has been
dummy i.v. is supplied and initialized, e.g.,
(COLLECT SQRT FROM 2 TO 5) returns (1.414 1.732 2.0 2.236).
TO form
is used to specify the final value for a numerical i.v.
Zl.ZZ
If
FROM is not specified, the i.v. is initialized to 1.
i.v.
has been speCified,
initialized.
If
BY
is
If no
a dummy i.v. is supplied and
not
specified,
the
i.v. is
automatically incremented by 1 after each iteration. 42 When
the i.v. is definitely being incremented, i.e. either BY is
not specified, or its operand is a positive number, the 1.5.
terminates when the i.v. exceeds the value of form (which is
reevaluated each iteration) e.g .•
(FOR X FROM 1 TO 10 ... _),
is equivalent to (FOR X FROM 1 UNTIL (X GT 10) _e).
Similarly, when the i.v. is definitely being decremented the
i.s. terminates when the i.v. becomes less than the value of
form (see description of BY).
BY x (with INION)
If IN or ON have been specified, the value of
~
determines
the tai I for the next iteration, which 1n turn determines
the value for the i. v. as described earl ier. i. e. the new
i .v. is
~
of the tail for IN, the tail itself for ON.
In
conjunction with IN, the user can refer to the current tail
within
x
by
(FOR Z IN L BY (CDOR
of
the
using
!) ... ).
the
e.g.
i. v.,
At translation time, the name
internal variable which holds
the
value
of
the
current tail is substituted for the i.v. throughout x.
For
example, (FOR X IN Y SY (CDR (MEMS 'FOO (COR X») COLLECT X)
specifies that after each iteration, cdr of the current tail
is to be searched for the atom FOO, and (cdr of) this latter
tail to be used for the next iteration.
42----------------------------------------------------------------------------except when both the operands to TO and FROM are numbers, and TO's operand
is less than FROM's operand, e.g. FROM 10 TO 1, in which case the i.v. is
decremented by 1 after each iteration. In this case, the 1.5. terminates
when the i.v. becomes less than the value of form.
23.23
BY x (without INION)
If IN or ON have not been used, BY specifies how the
If FROM or TO have
i.v. itself is reset at each iteration.
been specifiEtd, the i. v. is known to be numerical, so the
new
i. v.
llS
computed
by
adding
the
value
of
x
(which is reevaluated each iteration) to the current value
of the i.v., e.g., (FOR N FROM 1 TO 10 BY 2 COLLECT N) makes
a list of the first five odd numbers.
If ~ is a pClsitive number,43 the i.s. terminates when the
value of the i. v. exceeds the value of' TO' s operand.
If
~
is a negative number, the i.s. terminates when the value of
the
i.v.
becomes
than
less
operand,
TO's
(FOR I FROM N TO M BY -2 UNTIL (I LT M) ... ).
e.g.
Otherwise,
the terminating condition for each iteration depends on the
value of
~
< 0, the test is whether
operand, if x > 0 the test is
for that iteration: if
the i. v. is less than TO' 5
~
whether the i.v. exceeds TO's operand. otherwise if
~=O,
the
i.s. terminates unconditionally.44
If FROM or TO have not been specified, the i.v. is simply
reset
to
the
value
of
x
(FOR I FROM N BY 2 ... )
(FOR
I~N
after
is
each
iteration,
equivalent
e.g.
to .
BY (IPLUS I 2) ... ).
43----------------------------------------------------------------------------x itself, not its value, ,,,hich in general CLISP would have no way of
knowing in advance.
44
A temporary variable is used so that x is only evaluated once. However,
codo for TO's operand appea."s twice in- the translation, even though it is
evaluated only once.
23.24
FIRST form
form is evaluated once before the first iteration, e.g.
(FOR X Y Z IN L -- FIRST (FOO Y Z», and FOO could be used
to initialize Y and Z •.
FINALLY form
form is evaluated after the i.s. terminates. 45 For example,
(FOR X IN L BIND
FINALLY (RETURN
EACHTIME form
00 (IF ATOM X THEN
Y~O
V»~
Y~Y+1)
will return the number of atoms in L.
form is evaluated at the beginning of each iteration before,
and regardless of, any testing. For example, consider (FOR I
FROM 1 TO N 00 (... (FOO I) ... ) UNLESS (... (FOO I) ..• )
UNTIL ( ... (FOO
I)
•••
».
The user might want to set a
temporary variable to the value of (FOO I) in order to avoid
computing it three times each iteration. However, wi thout
knowing the translation, he would not know whether to put
the assignment in the operand to 00, UNLESS, or UNTIL, i.e.
which one would be
executed first.
problem by simply writing EACHTIME
AS var
He
J~(FOO
can
avoid
this
I).
is used to specify an iterative statement involving more
than
one
iterative
variable,
(FOR X IN Y AS U IN V 00 --) corresponds to maple.
e.g.
The i.s.
terminates when any of the terminating conditions are met,
e.g.
(FOR X IN Y AS I FROM I TO 10 COLLECT X) makes a list
of the first ten elements of Y, or however many elements
there are on Y if less than 10.
~i5--------------------------------~------------------ --------------------------
Except in the case of termination due to the appearance of a RETURN in some
operand. See page 23.26. Thus in (FOR X IN Y THEREIS NUMBERP FINALLY --)
the FINALLY operand would be evaluated if Y were exhausted, but not if a
number was found.
23.25
The operand to AS.
~,
specifies the new i. v.
For the
remainder of the i.s., or until another AS is encountered,
all
operators
refer
to
the
new
i. v.
For
example.
(FOR I FROM I TO Nt AS J FROM t TO N2 BY 2
AS K FROM N3 TO 1 BY -1 --) terminates when I exceedsNl, or
J
exceeds
N2,
or K becomes
less
than
1.
After
each
iteration, I is incremented by I, J by Z, and K by -1.
Miscellaneous
1.
Lowercase versions of all i.s. operators are equivalent to the uppercase,
e • 9 .,
2.
(for X in Y ... ).
Each 1.s. operator is of lower precedence than all INTERLISP forms,
so
parentheses around the operands can be omitted, and will be supplied where
necessary, e.g., BIND (X Y Z) can be written BIND X Y Z, OLD (X... form) as
OLD X"'form, WHEN (NUMBERP X) as WHEN NUMBERP X. etc.
3.
RETURN or GO may be used in any operand.
RETURN means return from the i.s.
(with the indicated value), not from the function in which tho i.S appears.
GO refers to a label elsewhere in the function in which the i.s. appears,
except
for
(GO ITERATE), which means transfer control to
the
iterate
portion of the loop, i.e. that part that resets the tail, increments the
counter,
or
whatever,
in
preparation
for
the
next
iteration.
The
appropriate label will be substituted for ITERATE.
4.
In the case of FIRST, FINALLY, EACHTIME, or one of the i.s.types, e.g. 00,
COLLECT, SUM, etc., the operand can consist of more than one form, e.g.,
COLLECT (PRINT X:l) X:2, in which case a PROGN is supplied.
5.
Each operand can be the name of a function, in which case it is applied to
23.26
the
( las t)
1. v. ,46 47 48 e. g. ; FOR X IN Y 00 PRINT WHEN NUMBERP,
is the
same as FOR X IN Y 00 (PRINT X) WHEN (NUMBERP X). Note that the 1. v. need
not be explicitly specified, e.g., IN Y 00 PRINT WHEN NUMBERP will work.
Errors in Iterative Statements
An error will be generated and an appropriate diagnostic printed if any of the
following conditions hold:
1.
Operator with null operand, i.e. two adjacent operators, as in FOR X IN Y
UNTIL DO
2.
Operand consisting of more than one form (except as operand to FIRST.
FINALLY, or one of the i.s.types), e.g., FOR X IN Y (PRINT X) COLLECT
3.
Same operator appears twice.
4.
Both IN and ON used on same i.v.
5.
FROM or TO used with IN or ON on same i.v.
6.
More than one i.s.type, e.g. a 00 and a SUM.
In 3, 4, or 5, an error is not generated if an intervening AS occurs.
If an error occurs. the i.s. is left unchanged.
46-" F~~ -~~ ~~ ~~~)~~: . -e-.-g-."- ~~~"~~~~E~~:-~O-I~-,--;h";"i~~~~~~~-~~" ~"l~~-Y"S- -~;;~i;~ -~~
the first i.v. in the i.s., whether explicity named or not. for example,
(IN Y AS I FROM 1 TO 10 00 PRINT) prints elements on Y, not integers
between 1 and 10.
47
Note that this feature does not make much sense for FOR, OLD, BIND, IN, or
ON, since they "operate- before the loop starts, when the i.v. may not even
be bound.
In the case of BY in conjunction wi th IN, the function 1s applied to the
current tail e.g., FOR X IN Y BY COOR .•.• 1s the same as FOR X IN Y BY
(COOR X) ... See page 23.23.
23.27
If no DO, COLLECT, JOIN or any of the other i.s.types are specified, CLISP will
first
attempt
FOR X IN Y
is
find an operand, consisting of more than one
i£!~JNT-1U
first form.
error
to
WHEN ATOM X, and in this case will insert
II
form,
00 after tho
(In this case, condition 2 is not considered to be met, and an
not generated.)
I feL ISP cannot find
such an operand,
15
still
translated.
e.'!}.
(WHILE form)
can
be
used
warning
a
However, the
message is printed: NO DO, COLLECT, OR JOIN: followed by the i.s.
1.5.
e.g.,
execute
to
form
repeatedly until its value is NJl.
Simi lar ly,
UNTIL,
,TO,
1f
no terminating t:ondi tion is detected,
or
a
RETURN
or
GO,
a
warning
POSSIBLE NON-TERMINATING ITERATIVE STATEMENT:
i . e.
no IN,
ON,
WHILE,
message
is
printed:
followed by the
1.s.
However,
since the user may be planning to terminate the i.s. via an error. control-E,
or a retfrom from a lower function. the i.s. is still translated.
Defining New Iterative Statement Operators
The i.s.type specifies what is to be done at each iteration, e.g. collecting
values on a list, adding numbers. searching for a particular condition, etc.
Each i.s. can have one and only one i.s.type.
The function i.s.type provides a
means of defining new i.s.types.
i.s.type[namo;form;init;val]
nar~
is the name of the i.s.type.
form to be evaluated at each iteration.
forD!
is the
In form SSVAL
can be used to reference the value being assembled,
I. V. to reference the current value of the 1. v.,
BODY
to
reference
the
body of
the
s ta ternen t,
and
i .e •
name's operand.
For example. for COLLECT, form would be (SETQ SSVAL (NCPNCl SSVAL BODY», for
23.28
SUM: (SSVAL~SSVAL+800y),49 for HEVER: (AND BODY (RETURN NIL», and for THEREIS:
(AND BODY (RETURN I.V.».
ini t specifies the initial value for SSVAL, e. g.
SUH, init is O.
for
val specifies the value to be returned
when the i.s. terminates.
i.s.type is undoable.
Examples:
1)
To define RCOLLECT, a version of COLLECT which uses cons instead of nconc1
and then reverses the list of values:
i.s.type[RCOLLECT;(SETQ SSVAL (CONS BODY SSVAl»;NIL;(DREVERSE SSVAl)]
2)
To define TCOLLECT, a version of COLLECT which uses tconc:
i.s.type[TCOLLECTj(TCONC SSVAL BODY); (CONS); (CAR SSVAL)]
3)
To define PRODUCT:
i.s.type[PRODUCT;(SSVAL~SSVAL*BOOY);l;SSVAL]
i.s.type performs the appropriate modifications to the property list for
ilS
~,
well as for the lower case version of name, and also updates the appropriate
spell-ing lists.
!.s.type can also be used to define synonyms for all i.s. operators, (not just
those
that
are
i.s.types).
by calling i.s.type with
i.s.type[WHERE;WHEN] makes WHERE be the same as WHEN.
forman
atom,
e.g.
Similarly, following
49--$$V~~:~~~Y-;~--~;;~-~~~~~~~--;i-(i;~US-SS~;L-B~~;):-~~--;h;;-~h~--C~;;~;-~;
function used in the translation, i.e. iplus, fplus, or plus, will be
determined by the declarations then in effect.
23.29
i.s.type[ISHIERE;THEREIS] one
i.s.type[FINO;FOR]
and
can write
(ISTHERE ATOM IN V).
i.s.type[SUCHTHAT;THEREIS].
one
and
following
can
write
(FINO X IN Y SUCH THAT X MEMBER Z).60
This completes the description of iterative statements.
23.8
CLISP
Trunsl~tions
The translation of infix
operato~s
CLISP
CLISP
by
replacing
the
and IFITHENIELSE statements are handled in
expr~ssion
with
the
corresponding
INTERLISP
expression, and discarding the original CLISP, because (1) the CLISP expression
is easily recomputable (by clis:.l!..!.!.l), 61 and (2) the INTERLISP expressions are
simple and straightforward.
In addition to saving the space required to retain
both the CL ISP and the INTERL ISP. another reason for discarding the original
CLISP is that it may contain errors that were corrected in the course of
translation, e.g.
the user writes
FO~FOOO:l,
N-8FOO X), etc.
If the original
CLISP were retained, either the user would have to go back and fix these errors
by
hand,
thereby
negating
the
advantage
of
having
DWIM
perform
these
corrections, or else DWIM would have to keep correcting these errors over and
over.
Where
(1)
or (2) are not the case, e.g. with iterative statements, pattern
50-----------------------------·----------------------------------------------In the current system, WHERE is synonymous with WHEN, SUCHTHAT and ISTHERE
with THERE IS, and FINO with FOR.
61
Note that clispif~ is sufficiently fast that it is practical for the user
to configur-c---fifsTNTERLISP system so that all expressions are automatically
c~i~e!J~ed immediately before they are presented to him.
For example, he
can define an edit macro to use in place of P which calls clisp~ on the
current expression before printing it. Similarly, he can inform prettyprint
to call clispify on each expression before printing it, etc.
23.30
matches,
record expressions, etc. 62 68 the original CLISP is retained (or a
slightly modified vorsion thereof), and tho translation is stored elsewhere,
usually in
clisparra~,
a hash array.
The interpreter automatically checks
this array using gethash when given a form car of which is not a function.
Similarly,
the compiler performs a gethash when given a form it does not
recognize to see if it has a translation, which is then compiled instead of the
form.
Whenever the user changes a CLISP expresson by editing it, the editor
automatically deletes its translation (if one exists), so that the next time it
is evaluated or dwimified, the expression will be retranslated.
and
~
the
edit
commands
translations, see page 23.15.
PPT
and
CLISP:
are
available
The function
for
examining
Similarly, if prettytranflg is T, prettyprint
will print the translations instead of the corresponding CLISP expression. 54
If clisparray is NIL,66 translations are implemented instead by replacing the
CLISP
expression
by
expression
an
(CLISPX_ translation. CLISP-expression),66
e.g.
of
the
form
(FOR X IN Y COLLECT (CAR X»
62--;~~-~~~~~i;:-;~~-;;~~;i~;~~~-~~-;:;~;-~;-(~~~~~-(~~~-(~~~~~~-;»):-~~~~~-~;
difficult to read. Therefore, such expressions are handled by retaining the
CLISP and storing the translation elsewhere, as described below.
63
Tho handling of translations for IFITHENIELSE statements is determined by
tho value of clispiftral}f!Q. If T, the translations are stored elsewhere,
and the (modified) CLISP retained as described below. If NIL, the
corresponding COND replaces the IFITHENIELSE expression. The initial value
of clisp1ftranflg is NIL.
&:1
Note that the user can always examine the translation himself by performing
(GETHASU expression CLISPARRAY).
66
66
is initially NIL, and #clisparray is its size. The first time a
translation is performed, a hash array of this size is created. Therefore
to disable clisparra~, both it and #c11sparray should be set to NIL.
cli~~arr~~
CLISP%
is an atom
consisting of the six ch.aracters C, L, I, S, P, and
space, which must be preceded by the escape character % in ordor for it to
be included as a part of an identifier. The intent was to deliberately
make this atom hard to type so as to make it unlikely that it would
otherwise appear in a user's program or data, since the editor and
prettyprint treat it very specially, as described above.
23.31
would be replaced by
(CLISPX_ (MAPCAR Y (FUNCTION CAR»
the
Both
FOR X IN Y COLLECT (CAR X».
editor and prettyprint know about CLISPX_ expressions and treat them specially
by
suppressing
the
translations:
(unless prettytranflg=T,
as
Prettyprint
described below),
prints
while
just
the
editor
the
CLISP
makes
the
translation completely invisible, e.g. if the current expression were the above
CLISPX
expression, F MAPCAR would fail to find the MAPCAR, and (3 ON) would
replace IN with ON, i.e. the editor operates as though both the ClISPX_ and the
MAPCAR were not there.
As with translations implemented via clisparray, if the
CLISP expression is changed by editing it, the translation is automatically
deleted.
CLISPX
expressions will interpret and compile correctly: CLISP%_ is defined as
an nlambda nospread function with an appropriate compiler macro. Note that if
the user sets
to NIL
~lisparray
p
he can then break, trace, or advise ClISPX_ to
monitor the evaluation of iter'ative statements, pattern matches, and record
operations. This technique will work even if clisparray was not NIL at the time
the expressions were originally translated, since setting clisparray to NIL
will effectively delete the translations, thereby causirig the CLISP expressions
to be retranslated when they are first encountered. Note that if the user only
wishes to moni tor the CLISP in a certain function, he can accomplish this by
embedding its definition in (RESETVAR CLISPARRAY NIL .).
If
a
ClISP%
translation
replaced
is
by
expression
is
encountered
and
transferred to the hash array,
just
the
CLISP.
Setting
clisparray
is
not
NIL,
the
and the ClISPY._ expression
prettytranflg
to
ClISPY._
causes
prott)':print to print CLISP expressions that have been translated in the form of
(ClISP%_ translation . CLISP-expression), even if the translation is currently
stored in clisparray. These two features together provide the user with a way
of dumping CLISP expressions together with their translations so that when
reloaded
(and
run
or
dwimified).
the
transferred to clisparray.
23.32
translations will
automatically
be
In summary, if prettytranflg=NIL, only the CLISP is printed (used for producing
listings).
If prettytranflg=T,
exporting
programs
to
systems
only the translation is
that do not
printed
provide CLISP.
and
(used for
to
examine
translations for debugging purposes).67 If prettytranflg=CLISPX_, an expression
of the form (CLISPX_ translation. CLISP) is printed, (used for dumping both
CLISP and translations).
The preferred method of storing translations is in
so that if any ClISPX_ expressions are converted while clisparral
.clisparr.~~,
is not NIL, they will automatically be converted so as to use clisparray.
!Clisparr~=NIl,
If
they will be left alone, and furthermore, new translations will
be implemented using CLISPX_ expressions.
Declarations
23.9
Declarations are used to affect the choice of INTERLISP function used as the
translation of a particular operator.
For example, A+8 can be translated as
either (IPLUS A B). (FPLUS A B). or (PLUS A B), depending on the declaration in
effect.
Similarly
(,1RPlACA X V).
.
X:l~Y
can
mean
(FRPLACA X V),
(RPLACA X Y),
and (!!A B> either (NCONCl A B) or (/NCONCl A B).
or
The table
below gives the declarations available in CLISP, and the INTERLISP functions
they
indicate.
affcctcd
by
The
choice oj Junction
these declarations,
i.e.
on all
CLISP
transformations
iteraiue statements.
are
pattern matche.s.
record operations. as well as infix and preJix operators.
The
user
ClISPOEC
can
make
(change)
and
giving
it
as
a global declaration by calling
its
argument
(CLISPO[C (QUOTE (FLOATING UNDOABLE»).
affect
the
speed
of
subsequent
a
list
of
the
function
declarations,
e.g.,
Changing a global declaration does not
CLISP
transformations,
since
all
CLISP
67----------------------------------------------------------------------------Noto tha t makeri Ie will reset prettytranflg to T, using resetvar, when
called with the option NOCLISP.
23.33
transformation are table driven (i.e. property list), and global declarations
arc accomplished by making the appropriate internal changes to CLISP at the
time of tho declaration.
If a function employs local declarations (described
below), there will be a slight loss in efficiency owing to the fact that for
each CLISP transformation, the declaration list must be searched for possibly
relevant declarations.
Declarations are implemented in the order that they are given, so that later
declarations
override
earlier
ones.
for
example,
the
declaration
FAST
specifies that FRPLACA, FRPLACD, FMEMB, and FLAST be used in place of RPLACA,
RPLAcn, MEMB, and LAST; the declaration RPLACA specifies that RPLACA be used.
Therefore,
the declarations (FAST RPLACA RPLACD) will cause FMEMB,
FLAST,
RPLACA, and RPLACO to be used.
Th~
initial global declaration is INTEGER and STANDARD.
Table of Declarations
Declaration
INTERLISP functions to be used
INTEGER or FIXED
IPLUS, IMINUS, IDIFFERENCE, ITIMES, lQUOTIENT, ILESSP,
IGREATEFlP
FLOATING
FPLUS, fMINUS, FDIFFERENCE, FTIMES, FQUOTIENT, LESSP,
FGTP
MIXED
PLUS,
I~INUS,
DIFFERENCE,
TIMES t
QUOTIENT,
LESSP.
GREATER~t
FAST
FRPLACA, FRPLACD, FMEMB, FLAST, FASSOC
UNDOABLE
IRPLACA, IRPLACD, INCONC, INCONC1, IMAPCONC, IHAPCON
STANDARD
RPLACA, RPLACO,
MAPCONC, MAP CON
RPLACA, RPLACD,
/RPLACA, ...
corresponding function
23.34
HEMS,
LAST,
ASSOC,
NCONC,
NCONC1,
Local Declarations
The user can also make declarations affocting a selected function or functions
inserting an expression of the form (CLISP: . declarations)
inunediately
following the argument list, i.e<.; as CADDR.of the definition.
Such local
by
declarations take precedence over global declarations.
Declarations affecting
selected variables can be indicated by lists, where the first element is the
name
of a variable,
variable.
and the rest of the list the declarations
For example,
(CLISP: FLOATING (X INTEGER»
for
that
specifies that in this
function integer arithmetic be used for computations involving X, and floating
arithmetic for all other computations. 58 The user can also make local record
declarations
by
(ARRAYRECOR'D --).
inserting
etc.,
1n
a
record
the
local
declaration,
declaration
e.g.
list.
(RECORD --),
Loca I
record
declarations override global record declarations for the function in which they
appear.
Local declarations can also be used to override the global setting of
certain DWIM/CLISP parameters effective only for transformations within that
function,
(variable
by
including in the local declaration an expression of the form
= value),
e.g. (PATVARDEFAULT
= QUOTE).
The ClISP: eXJH"ession is converted to a comment of a special form recognized by
CL I SP.
about
Whenever a CLISP transformation that is affected by declarations is
to be performed in a function,
this comment will be searched for a
relevant declaration, and if one is found, the corresponding function will be
used.
Otherwise,
if none are found, the global declaration(s) currently in
effect will be used.
-
.
6,8 - -: ~ ~~~ ~ ~;I~ ~: ~~~~~ -;;;;e"" ~~; - :~~~~b~~. -i~~"e-l"f-"~;" ~~ - ~-p"e-;a-;d-." - - ;~; - ;~;~~
i; ~
with the declaration (FLOATING (X INTEGER»
in effect, (FOO X)+(FIE X)
would translate to FPLUS, i.e., use floating arithmetic, even though X
nppears somewhere inside of the operands, whereas X+(FIE X) would translate
to IPLUS.
I f there are declarations involving both operands, e. g. X+Y,
with (X FLOATING) (Y INTEGER), whichever appears first in the declaration
list will he used.
23.35
Local declarations are effective in the order that they are given, so that
declarations
later
can
be
used
to
override
earlier
ones,
e.g.
(CLISP: FAST RPLACA RPLACO) specifies that fMEMB, fLAST, RPLACA, and RPLACO be
used.
An exception to this is that declarations for specific variables take
precedence of general, function-wide declarations, regardless of the order of
appearance, as in (CLISP: (X INTEGER) FLOATING).
Cl ispi fy- also checks the declarations in effect before selecting an infix
operator
to
ensure
that
the corresponding CLISP construct would
translate back to this form.
in
fact
For example, if a FLOATING declaration is in
effect, clispify will convert (FPlUS X Y) to X+Y, but leave (IPLUS X Y) as ,is.
Note that if (FPlUS X Y) is CLISPIFVed while a FLOATING declaration is under
effect, and then the declaration is changed to INTEGER, when X+Y is translated
back to INTERLISP, it will become (IPLUS X V).
The Pattern Match Compilar 69
23.10
CLISP contains a fairly general pattern match facility.
The purpose of this
pattern match facility is to make more convenient the speCifying of certain
tests that would otherwise be clumsy to write (and not as intelligible), by
allowing the user to give instead a pattern which the datum is supposed to
match.
Essentially,
the
user writes
"Does
the
(expression)
X look
like
(the pattern) P?" For example, X:(& 'A -- 'B) asks whether the second element
of X is an A, and the last element a B.
performed by computing (once)
1~he
The implementation of' the matching is
equivalent INTERLISP expression which will
perform the indicated operation, and substituting this for the pattern, and not
by invoking each time a general purpose capability such as that found in FLIP
~~--T------------------------------------------------------------------~--------
he pattern match compiler was written by L. M. Masinter.
23.36
or
PLANNER.
(AND
for
example,
(EQ (CADR X) (QUOTE A»
the
translation
(EQ-(CAR (LAST X»
of
X:(& fA -- '8)
(QUOTE B»).' Thus
is:
the CLISP
pattern match facility is really a Pattern Compiler, and the emphasis in its
design and implementation has been more on the efficiency of object code than
on generality and sophistication of its matching capabilities.
The goal was to
provide a facility that could and would be used even where efficiency was
paramount, e.g. in inner loops.
As a result, the CLISP pattern match facility
does not contain (yet) some of the more esoteric features of other pattern
Inatch
languages,
patterns,
such
recursion,
as
repeated
patterns,
disjunctive
etc.
However,
the user
can
be
and
conjunctive
confident
that
what
facilities it does provide will result in INTERLISP expressions comparable to
those he would generate by hand. 60
The syntax for pattern match expressions is form:pattern, where pattern is a
list as described below.
patterns,
i.e.,
the
As with iterative statements,
corresponding
INTERlISP
expressions,
flisparray, a hash array, as described on page 23.30.
form:pattern,
is
replaced
(MATCH form WITH pattern).
by
an
the translation of
are
stored
in
The original expression,
expression
of
the
CLISP also recognizes expressions input
form
in this
form.
If form appears more than once in the translation, and it is not either a
vari able.
or an expression that
(CDDR Z), etc.,
is easy to (re )compute,
such
as
(CAR Y).
a dummy variable will be generated and bound to the value of
form so that .torm is not evaluated a multiple number of times.
for example,
the translation of (FOO X):(S 'A S) is simply (HEMB (QUOTE A) (FOO X», while
the translation of (Foo X):('A '8 --) is:
60---------------------------------------------------------------------------Wherever possible, already existing INTERLISP functions are used in the
translation, e.g., the translation of (S 'A S) uses HEHB, (S ('A S) S) uses
ASSOC, etc.
23.37
[PROG (SS2) (RETURN
(AND (EQ (CAR (SETQ SS2 (FOO X»)
(QUOTE A»
(EQ (CADR SSZ) (QUOTE Bl.
In the interests of efficiency, the pattern match compiler assumes that all
lists end in NIL, i.e. there aro no LISTP checks inserted in the translation to
check
tails.
For
example,
(AND (EO (CAR X) (QUOTE A»
(A . B).
translation
the
X:( 'A & --)
of
is
(COn X». which will match with (A B) as well as
Similarly. the pattern match compiler does not insert LISTP checks on
elements, e.g. X:«'A --) --) translates simply as (EO (CAAR X) (OU01E A», and
X: «S1 S1 --) --) as (CODAR X) .61 Note that the user can explicitly insert
LISTP
checks
himself
by
using
@.
as
described
on
X:«S1 S1 --)@lISTP --) translates as (AND (LISTP (CAR X»
page
23.40,
e.g.
(CDDAR X».
Pattern Elements
A pattern consists of a list of pattern elements.
Each pattern element is said
to match either an element of a data structure or a segment.
(cf. the editor's
pattern matcher, "--" matches any arbitrary segment of a list, while
&
or a
subpattern match only one element of a list.) Those patterns which may match a·
segment of a list are called SEGMENT patterns; those that match a single
element are called ELEMENT patterns.
61------------------------------·----------------------------------------------The insertion of LISTP checks for elements is controlled by the variable
pi!_~LL~~p~h!:ck.
X:«
When
~atlistpcheck
'A --) --) translates as:
is T, LISTP checks are inserted, e.g.
(AND
(LISTP X) (LISTP (CAR X»
(EQ (CAAR X) (QUOTE A»).
is initially NIL. Its value can be changed within a
particular function by using a local declaration, as described on page
~atlistpcheck
23.35.
23.38
Element Patterns
There are several types of element patterns, best given by their syntax:
PATTERN
MEANING
51. or &
matches an arbitrary element of a list
'expression
matches
only
an
element
which
is
equal
to
the
given
expression e.g., tA,62 t(A B).
=form
matches only an element which is equal to the value of form,
e.g., =X, =(REVERSE V).
==form
same as =, but uses an
atom
treatment depends on setting of
~
check instead of equal.
~atvardefault.
If
~atvardefault
is ' or QUOTE, same as 'atom.
If
~atvardefault
is = or EQUAL, same as =atom.
If
~atvardefault
is == or EQ. same as ==atom .
If
~atvardefault
is .. or SETQ, same as atom..&.
~atvardefault
is initially =.68
Note: numbers and strings are always interpreted as though
=, regardless of its setting.
involving small
~,
~atvardefault
were
memb, and assoc are used for comparisons
i~tegers.
62----------------------------------------------------------------------------!,~q,
mcmb, and assoc are automatically used in the translation when the
Quoted expression is atomic, otherwise equal, member, and sassoc.
63
p-atvardefault can be changed within a particular function by using a local
declaration, as described on page 23.35.
23.39
matches a list
(pattern 1 ... pattern n ) n ~ 1
patterns, e.n., (& &), (-- 'A).
element-pattorn@function-object
matches an
which
element
if
matches
the
given
the element-pattern
matches it, and the function-object (name of a functibn or a
LAMBOA expression) applied to that element returns non-NIL,
e.g. &@NUMBERP matches a number, ('A --)@FOO
match~s
a list
whose first element is A, and for which FOO applied to that
list is non-NIL. 64
matches
any
arbitrary
If
elemont.
succeeds, the element which matched the
the
*
entire
match
will be returned
as the value of the match.
Note: normally. the pattern match compiler constructs an expression whose value
is
guaranteed to be non-NIL
However, if a
if tho match succeeds and NIL if .it fails.
* appears in the pattern, the express·ion generated will either
return NIL if the match fails, or whatever matched the - even though that may
be
(AND
NIL.
(EQ
For
eXelmple,
X:( 'A
(COR X)
(CADR X».
(CAR X) (QUOTE A»
-element-pattern
matches
an
element
if
element-pattern, e.g.
the
-'A,
* --)
element
-=X,
translates
is
not
matched
as
by
-(-- 'A --).
64----------------------~------------------------------------------------------
For 'simple' tests,
attempted with the
(AND (LISTP (CAR X»
the function-object is applied before a match is
pattern, e.g. «-- 'A --)@LISTP --) translates as
(MEMB (QUOTE A) (CAR X»), not the other way around.
23.40
Segment Patterns
of
zero
The difference between $ and -- is in the type of search they generate.
For
$,
matches
or --
any segment
of
a
list
(including
one
length) .
example, X:(S 'A 'B S) translates as (EQ (eADR (MEMB (QUOTE A) X»
whereas
X:(--
'A 'B S)
(AND (EQ SS2 (QUOTE A»
(S 'A 'B S) would be
translates
as:
[SOME X (FUNCTION (LAMBDA (SS2 SS1)
(EQ (eADR SSI) (QUOTE BJ.
II
(QUOTE B»,
Thus,
Is the element following the
!tr~
a
paraphrase
of
t A a B1", whereas a
paraphrase of (-- 'A 'B $) would be -Is there anu A immediately followed by a
B?" Note that the pattern employing $ will result in a more efficient search
than
tha t
employing
(X Y Z A M N 0 A B
Essentially.
searching,
once
However.
e).
a
(S' A 'B S)
wi 11
not
rna tch
wi th
but (-- 'A 'B S) will.
pattern
whereas
following
produces
a
a $ matches,
translation
that
searching until there is no possibility of success.
the $
will
never
always
resumes
continue
However, if the pattern
match compilor can deduce from the pattern that continuing a search after a
particular failure cannot possibly succeed, then the translations for both -nnd :& will be the same. For example. both
translate
as
(eDDDR (MEMB (QUOTE A)
X»,
X:(S 'A S3 $) and (-- 'A S3 --)
because
if
there
are
not
three
(!lements following the first A, there certainly will not be three elements
following subsequent A's, so there is no reason to continue searching, even for
Similarly, (S 'A
S2, $3, etc.
$
'B S) and (-- 'A -- '8 --) are equivalent.
matches a segment of the given length.
Note that $1 is not
a segment pattern.
!element-pattern
matches any segment which the given element pattern would
match as a list.
For example,
23.41
if the value of FOO is
!=FOO will match the segment ... ABC
(A B C)
Note that !. is permissible and means
etc.
Value-of-match~$,
e.g.
X:(S 'A ,.) translates to (COR (MEMB (QUOTE A) X».
Note: since ! appearing in front of the last pattern specifies a match with
some tail of the given expression, it also makes sense in this case for a ! to
appear in front of a pattern that can only match with an atom, e.g., (S2 ! 'A)
means match if cddr of the expression is the atom A. Similarly, X: ($ r"A)
translates to (EQ (COR (LAST X»
!atom
treatment
(QUOTE A».
depends
on
setting
or QUOTE,
patvardefault, is
I
discussion) .
patvardefault
!=atom.
If
of
patvardefault.
same as
as
If patvardefault is == or EQ, same as !==atom.
If
~
or SETQ, same as
= or
(see above
same
patvardefault is
is
! 'atom
If
EQUAL,
atom~$.
The atom '.' is treated exactlu like! .66 In addition, if a
pattern ends in an atom, the '.'
is first changed to
!.
e.g., (S1 . A) and (S1 ! A) are equivalent, even though the
atom
I
.
,
does not explicitly appear in the pattern.
Segment-pattern@function-object
matches
it,
matches
and
the
corresponding segment
a
segment
function
(as a
if
the
object
list)
segment-pattern
applied
returns
to
non-NIL,
the
e.g.
~~-----------------------------------------------------------------------------
Wi th one exception. namely '.'
preceding an assignment does not have the
interpretation tha'~ ! has proceding an assignment (see page
23.43).
For
example,
X:( 'A • FOO~'B) ,
translates
as:
(AND (EQ (CAR X) (QUOTE A»
(EQ (CDR X) (QUOTE B»
(SETQ Faa (COR X»),
but X:( 'A ! FOO~'B) translates as:
(AND (EQ (CAR X) (QUOTE A»
(NULL (COOR X»
(EQ (CAOR X) (QUOTE B»
(SE TQ8)0 (COR X»).
special
23.42
(S@COOR '0 S) matches (A B C 0 E) but not (A B 0 E), since
CODR of (A B) is NIL.
an
Note:
@ pattern
applied
to
a
segment
will
require
computing
the
corresponding structure (with ldiff) each time the predicate is applied (except
when tho segment in question is a tail of the list being matched).
Assignments
Any pat tern element may be preceded by a variable and a .... , meaning if the
match succeeds (i.e., everything
that
pattern
mat~hes).
matc'fe~
X,:(S2
Y"'S3) will set Y to (C 0 E).
entire match has succeeded.
For
element.
what
Thus,
the variable given is to be set to
example,
if
match with
=
(A B C 0 E),
Assignments are not performed until the
assignments cannot be used to specify a
search for an element found earlier in the match, e.g.
not
X
(A ABC ... ). 67 This type of match
X:(Y"SI =Y __ )66 will
is achieved
by using
place-markers, described below.
If the variable is preceded by a !,
~he
assignment is to the tail of the list
as of that point in the pattern, i.e. that portion of the list matched by the
remainder of the pattern. For example, if X is (A BCD E), X:(S !Y.. 'e '0 S)
sets
Y to
(C 0 E),
i.e.
cddr of X.
In other words,
when
precedes an
assignment, it acts as a modifier to the .. , and has no effect whatsoever on the
pattern itself, e.g.
X:( 'A 'B) and X:('A !FOo..'B) match identically, and in
the latter case. FOa will be set to CDR of X.
60---------------------------------------------------------------------------The translation of this pattern is:
(COND «ANO (CDR X) (EQUAL (CADR X)
(SETQ Y (CAR X»
V»~
T».
The AND is because if Y is NIL, the pattern should match with (A NIL), but
not with just (A). The T is because (CAR X) might be NIL.
unless, of course, the value of Y was A before the match started.
23.43
Note:
*~pattern-element
X:(S tA
*~(
and
!*~pattern-element
are
acceptable,
e.g~
'8 --) --) translates as:
[PROG (SS2) (RETURN
(AND (EQ (CAAOR (SETQ SS2 (MEMB (QUOTE A) X»)
.
,(QUOTE B»
(CADR SS2]
Place-markers
Variables of
the form In,
!l a number,
are called place-markers,
interpreted specially by the pattern match compiler.
and are
Place-markers are used in
a pattern to mark or refer to a particular pattern element. Functionally. they
are used like ordinary variable!s, i.e. they can be assigned values, . or used
freely in forms appearing in the pattern, e.g.
the list (2 3).
X:(#l~Sl
=(ADDI II»
will match
However, they are not really variables in the sense that they
are not bound, nor can a function called from within the pattern expect to be
able to obtain their values.
For convenience"
regardless of the setting of
patvarderault, the first appearance of a defaulted, place-marker is interpreted
as though
patv~rdefault
as X:(#l =(ADDI /1».
were
~.
Thus the above pattern could have been written
Subsequent appearances of a place-marker are interpreted
as though patvardefault were
=.
For example, X:(II #1 --) is equivalent to
X:(#l~Sl =#1 --), and translates as (AND (CDR X) (EQUAL (CAR X) (CAOR X».68
Replacements
Any pattern element may be followed by a
succeeds,
I~'
and a form, meaning if the match
the part of the data that matched is to be replaced (e.g., with
~~-----------------------------------------------------------------------------
Just (EQUAL (CAR X) (CADR X»),would incorrectly match with (NIL).
23.44
RPlACA or RPLACO)69 with the value of Source Exif Data:
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