(lisp)

TL;DR

A simple interpreter for a Scheme-like language built in Python3.

What it can do?

(lisp) has a set of essential Lisp special forms and build-in functions:

Special forms:

• let
• define
• if
• cond
• set!
• quote
• quasiquoute
• unqote

Built-in functions:

• Standard arithmetic and comparison: +, *, >, <=, abs, ...
• Classic Lisp: cons, car, cdr, list, eq?
• Short-circuit logic: and, or
• Introspection: function?, list?, atom?, number?, symbol?
• List processing: map, filter, fold, sum, reverse, mul

How to use it?

(lisp) comes with a simple REPL and ability to read and evaluate programs from files.

• REPL

mbpro:lisp begor$ python lisp
(lisp) - a minimalistic LISP interpreter.
(lisp)> (define square (lambda (x) (* x x)))
<function procedure.<locals>.<lambda> at 0x7fdff9940598>
(lisp)> (square 42)

1764

• Files

mbpro:lisp begor$ cat examples/fact.lisp
(define fact
  (lambda (n)
    (if (<= n 1)
      1
      (* n
        (fact (- n 1))))))

(fact 100)

mbpro:lisp begor$ python lisp examples/fact.lisp
93326215443944152681699238...

Any tests?

mbpro:lisp begor$ pytest tests/
======================================= test session starts ========================================

tests/unit/env_test.py ....
tests/unit/eval_test.py ............................................
tests/unit/parser_test.py ........

==================================== 56 passed in 0.07 seconds =====================================