LISP on TeX

A LISP interpreter written only with TeX macros. It works as a style file of LaTeX. LISP on TeX adopts static scoping, dynamic typing, and eager evaluation. We can program easily with LISP on TeX.

Summary

To use LISP on TeX, you should include the lisp-on-tex package.

\usepackage{lisp-on-tex}

If you do it, you can write LISP codes as a argument of \lispinterp.

\lispintrep{
  (\some \LISP 'codes')
  % example
  (\define (\sum \a \b) (\+ \a \b))
}

In LISP on TeX, a symbol is a control sequence; a string is tokens surrounded by quotation marks; and an integer is a TeX's integer using colon prefix.

Installation

Put all files into your TEXMF tree.

Details

Class Options

Option Name	Meaning
noGC	Never using GC (default)
markGC	Using Mark-Sweep GC
GCopt=...	Passing option to the GC engine

Currently, LISP on TeX supports Mark-Sweep GC. If you want to use it, you should use markGC option. You can also control heap size by using GCopt={heapsize=n} where n is greater than 3000. The default heap size is 32768. For example, the code

\usepackage[markGC, GCopt={heapsize=5000}]{lisp-on-tex}

shows that LISP on TeX uses Mark-Sweep GC and the heap size is 5000.

Syntax

Kinds	Literals	Examples
CONS Cell	( obj ... . obj ), ( obj ... )	(\+ :1 :2)
Integer	: TeX's integer	:42, :"3A
String	' TeX's balanced tokens '	'\foo{bar}baz'
Symbol	TeX's control sequence	\cs
Boolean	/t or /f
Nil	()
Skip	@ TeX's skip	@12pt plus 34cm
Dimen	! TeX's dimen	!56pt

Functions and Special Forms

Definition

\define : Define a symbol.

---

% symbol form
(\define \foo :42) % ()
\foo % :42
% function form
(\define (\foo \n) (\* \n :2))
(\foo :3) % :6

\defineM : Define a mutable symbol.

---

\setB : Rewrite a mutable symbol.

---

% symbol form
(\defineM \foo :42) % ()
\foo % :42
(\setB \foo 'bar')
\foo % 'bar'

\defmacro : Define a macro.

---

\macroexpand : Expand a macro

---

(\defmacro (\foo \x) (\list (\quote \bar) \x \x \x)) % ()
(\macroexpand (\quote (\foo :1))) % (\bar :1 :1 :1)

\lambda : Create a function.

---

% normal form
((\lambda (\x) (\+ \x :2)) :3) % :5
% list form
((\lambda \x \x) :1 :2) % (:1 :2)
% remain argument form
((\lambda (\x . \y) \y) :1 :2 :3) % (:2 :3)

\let : Define local symbols.

---

(\define \x 'foo')
(\let ((\x :4) (\y :3)) (\+ \x \y)) % :7
\x % 'foo'

\letM : Define mutable local symbols.

---

(\letM ((\x 'foo'))
  (\begin (\setB \x 'bar') \x)) % 'bar'

\letrec : Define local symbols recursively.

---

(\letrec
  ((\oddQ (\lambda (\n)
             (\lispif (\= \n :0) /f (\evenQ (\- \n :1)))))
   (\evenQ (\lambda (\n)
             (\lispif (\= \n :0) /t (\oddQ (\- \n :1))))))
   (\oddQ :42)) % /f

Control Flow

\lispif : Branch.

---

(\lispif /t 'true' 'false') % 'true'
(\lispif /f 'true' 'false') % 'false'

\begin : Execute expressions.

---

(\letM ((\x :1)) (\begin (\setB \s 'foo') \x))
% 'foo'

\callOCC : One-shot continuation.

---

(\defineM \x 'unchanged')
(\callOCC (\lambda (\c)
             (\begin (\c '\foo ')
                     (\setB \x 'changed')))) % '\foo '
\x % 'unchanged'
(\callOCC (\lambda (\c) :42)) % :42

String Manipulations

\concat : Concatenate tokens.

---

(\concat '$' '\foo ' '{bar}' '$') % '$\foo {bar}$'

\intTOstring : Convert a integer to TeX's tokens.

---

(\intTOstring :42) % '42'

\stringTOint : Convert a string to integer

---

(\stringTOint '42') % :42

\group : Grouping.

---

(\group '\some {tokens}') % '{\some {tokens}}'

\ungroup : Ungrouping.

---

(\ungroup '{\some {tokens}}') % '\some {tokens}' 

\expand : Expand tokens.

---

\newcommand\foo[1]{I got #1!}
\lispinterp{
  (\expand '\foo{Foo}') % 'I got Foo!'
}

Arithmetical Functions

\+ : Addition.

---

(\+) % :0
(\+ :1 :2) % :3
(\+ :3 :4 :5) % :12

\- : Subtraction.

---

(\- :1) % :-1
(\- :3 :2) % :1
(\- :3 :2 :1) % :0

\* : Multiplication.

---

(\*) % :1
(\* :2 :3) % :6
(\* :3 :4 :5) % :60

\/ : Division.

---

(\/ 2) % :0 (1/2 -> 0)
(\/ 7 2) % :3

\mod : Modulo.

---

(\mod :42 :23)  % :19
(\mod :3 :2)    % :1
(\mod :3 :-2)   % :1
(\mod :-3 :2)   % :-1
(\mod :-3 :-2)  % :-1

\>, \<, \geq, \leq : Comparison.

---

(\> :3 :2)   % /t
(\< :2 :3)   % /t
(\geq :3 :2) % /t
(\geq :3 :3) % /t
(\leq :2 :3) % /t
(\leq :3 :3) % /t

Some predicates.

---

(\isZeroQ :0)    % /t
(\positiveQ :42) % /t
(\negativeQ :-2) % /t

\max : Maximum.

---

(\max :-10 :-5 :0 :5 :10) % :10

\min : Minimum.

---

(\min :-10 :-5 :0 :5 :10) % :-10

Logical functions

\and, \or, \not : Logical and, or, not

---

(\and /t /t) % /t
(\and /t /f) % /f
(\or /t /t)  % /t
(\or /t /f)  % /t
(\not /t)    % /f

Traditional LISP Functions and Special Forms

\quote : Quote.

---

(\quote :42) % :42
(\quote (\+ :1 :2)) % (\+ :1 :2)

\cons, \car, \cdr : CONS, CAR, CDR

---

(\cons :42 'foo') % (:42 . 'foo')
(\car (\quote (:1 :2))) % :1
(\cdr (\quote (:1 :2))) % (:2)

\list : Create a list

---

(\list :1 :2 (\+ :3 :4)) % (:1 :2 :7)

\length : Get the length of a list.

---

(\length ()) % :0
(\length (\list :1 :2 'three')) % :3

\map : Map function.

---

(\define (\f \x \y \z) (\+ \x \y \z))
(\map \f (\list :1 :2 :3)
         (\list :4 :5 :6)
         (\list :7 :8 :9)) % (:12 :15 :18)

\nth : Get the n-th value of a list (starting with 0).

---

(\nth (\list 'foo' 'bar' 'baz') :1) % 'bar'

\= : Equality.

---

(\= '42' :42) % /f
(\= :23 :23) % /t
(\= (\cons :1 'foo') (\cons :1 'foo')) % /f
(\= 'foo' 'foo') % /t

\texprint : Convert a object to TeX's tokens and output it to the document

---

(\texprint (\concat '\foo' (\group '42'))) % return () andoutput \foo{42}
(\texprint :42) % output 42

\print : (For test) output a object as TeX's tokens

---

(\print ()) % output ()
(\print (\quote \foo)) % output \string\foo
(\print :42) % output :42
(\print 'bar') % output 'bar'

Type predicates

---

(\symbolQ (\quote \cs))
(\stringQ 'foo')
(\intQ :42)
(\booleanQ /f)
(\dimenQ !12pt)
(\skipQ @12pt plus 1in minus 3mm)
(\pairQ (\cons :1 :2))
(\nilQ ())
(\funcQ \+)
(\closureQ (\lambda () ()))
(\defmacro (\x) ())
(\macroQ \x)
(\listQ ())
(\listQ (\list :1 :2))
(\atomQ :23)
(\atomQ 'bar')
(\procedureQ \+)
(\procedureQ (\lambda () ()))

LaTeX Utils

\readLaTeXCounter : Read an integer from LaTeX

---

\setcounter{foo}{42}
\lispinterp{
  (\readLaTeXCounter 'foo') % :42
}

\message : Wrapper of LaTeX's message

---

(\message 'output') % output "message" to console and return ()

Others

\read : Read a LISP expression from stdin

---

(\read) % input :42 and return it

\fgets : Read a string from stdin.

---

(\fgets) % input \some {tokens} and return '\some {tokens}'

Additional Packages

Fixed Point Numbers

The package lisp-mod-fpnum adds fixed point numbers to LISP on TeX. Load it by \usepackage:

\usepackage{lisp-on-tex}
\usepackage{lisp-mod-fpnum}

Syntax

Kinds	Literals	Examples
Fixed point number	+{fpnum:: number }	+{fpnum::1.23}

Functions

\fpnumTOstring : Convert a fixed point number to a string.

---

(\fpnumTOstring +{fpnum::1.23}) % '1.23'

\fpplus : Addition.

---

(\fpplus +{fpnum::1.2} +{fpnum::1.4}) % 2.59999 (arithmetical error)

\fpminus : Subtraction.

---

(\fpminus +{fpnum::4.2} +{fpnum::2.3}) % 1.9

\fpmul : Multiplication.

---

(\fpmul +{fpnum::1.2} +{fpnum::1.4}) % 1.67998

\fplt : Comparison.

---

(\fplt +{fpnum::1.2} +{fpnum::2.3}) % /t

Regular Expressions

The package lisp-mod-l3regex is thin wrapper of l3regex. Load it by \usepackage:

\usepackage{lisp-on-tex}
\usepackage{lisp-mod-l3regex}

Functions

\regMatch, \regMatchResult : Match.

---

(\regMatch 'hoge+' 'hogeeeeeee') % /t
(\regMatchResult '(\w+)\s+is\s+(\w+)\.' 'He is crazy.')
% ('He is crazy.' 'He' 'crazy')

\regExtract : Extraction.

---

(\regExtract '\w+' 'hello regex world') % ('hello' 'regex' 'world')

\regReplaceAll, \regReplaceOnce : Replace.

---

(\regReplaceAll '(\w+?)to(\w+?)' '$\1\c{to}\2$' 'AtoB BtoC') % '$A\to B$ $B\to C$'
(\regReplaceOnce 'foo+' '[\0]' 'foooofooooooo') % '[foooo]fooooooo'

\regSplit : Split.

---

(\regSplit '/' '/path/to/hogehoge') % ('' 'path' 'to' 'hogehoge')

TODOs

• Writing user manual
• Add functions and special forms

CHANGELOG

Dec. 18, 2024 : 2.1

---

• Add stringTOint function, thanks for @homologic

Oct. 25, 2015 : 2.0

---

• Add GC
• Refine some special forms like define
• Add checking #args for some functions.
• Add thin wrapper of l3regex

Jul. 12, 2014 : 1.3

---

• Add one shot continuations.
• Add some arithmetical functions.
• Debug environment.

Jan. 03, 2014 : 1.2

---

• Added TUG2013's examples.
• Improved the performance.

Aug. 10, 2013 : 1.1

---

• Added letrec and expand.
• debug

Mar. 04, 2013 : 1.0

---

Licence

Modified BSD (see LICENCE)

---

HAKUTA Shizuya <hak7a3@live.jp>

https://github.com/hak7a3/lisp-on-tex