gfngfn / tex_of_ocaml

A compiler for untyped lambda terms to TeX code

tex_of_ocaml

Note: This project is a kind of joke and probably not of practical use.

Summary

This software consists of the following:

• src/: A compiler for call-by-value untyped lambda-terms (which have OCaml-like syntax) to (Knuthian) TeX code fully-expandable by \edef (written in Rust)
• src_tex/secd.sty: A virtual machine based on the SECD machine (written in TeX itself)

Example usage

Invoke:

$ SRC=examples/example3.txt
$ TARGET_DIR=_generated/
$ TARGET_NAME=example3.tex

# Prepare the target directory:
$ mkdir -p $TARGET_DIR
$ cp src_tex/secd.sty $TARGET_DIR

# Compile a source file to target code:
$ cat $SRC
(fun x -> fun f -> f (arabic (add 1 x))) 42 (append "foo")
$ cargo run $SRC -o $TARGET_DIR/$TARGET_NAME

# Evaluate target code and produce a PDF file:
$ cd $TARGET_DIR
$ latexmk $TARGET_NAME

Then you can see “foo43” on the generated PDF.

Syntax

e ::=
    '(' e ')'
  | x                         (variables)
  | 'fun' x '->' e            (lambda abstractions)
  | e e                       (applications)
  | 'let' x '=' e 'in' e      (let-bindings)
  | 'if' e 'then' e 'else' e  (conditionals)
  | p                         (primitive operations)
  | b                         (Boolean literals)
  | n                         (integer literals)
  | s                         (string literals)
x ::= (identifiers)
p ::= 'add' | 'sub' | 'mult' | 'append' | 'arabic' | 'iszero'
b ::= 'true' | 'false'
n ::= (non-negative decimal integer literals)
s ::= (double-quoted string literals)

Supported primitives

• add : nat -> nat -> nat
  • integer addition
• sub : nat -> nat -> nat
  • integer subtraction where negative results are truncated to zero
• mult : nat -> nat -> nat
  • integer multiplication
• append : string -> string -> string
  • string concatenation
• arabic : nat -> string
  • converts integers to strings
• iszero : nat -> bool
  • checks whether the given integer is zero