axiomatic-lisp
Inspired by this article by Eric Normand, an implementation of LISP from [the original McCarthy paper] (https://www.brinckerhoff.org/clements/csc530-sp09/Readings/mccarthy-1960.pdf).
The goal is to implement a working LISP with very few lines of C.
S-Expressions are implemented, with the following "axioms" from the McCarthy paper:
- ATOM: atom x -> T if x is an atom, F if not
- CAR: car (a b ...) -> (a)
- CDR: cdr (a b ...) -> (b ...)
- CONS: cons a (b) -> (a b)
- EQ: eq a b -> T if a and b are the same atom, F if a and b are different atoms, else NIL
The following to build math capabilities:
- ADD: add 1 2 -> 3
- SUB: sub 3 2 -> 1
The following intermediate functions made from the above axioms:
- QUOTE: (quote (car (a))) -> (car (a)) [ie. not executed]
The following (non-user-executable) intermediates from the McCarthy paper:
- ASSOC:
[X; ((W, (A, B)), (X, (C, D)), (Y, (E, F)))] => (C, D) - PAIR:
[(A, B, C); (X, (Y, Z), U); (TAIL)] => ((A, X), (B, (Y, Z)), (C, U), TAIL)- the "tail" addition removes the need for "append" in the kernel
- EVLIS:
[((QUOTE T), (X), (ADD, 1, 2))] => (T, NIL, 3) - EVCON:
[(((EQ, A, B), 1), ((EQ, A, A), 2), ((T), 3))] => 2 - EVAL, APPLY, APPQ: see paper
And, the ability to define functions (puts a label/lambda in global environment):
- DEFUN: defun (x, y, ...) (S-Expression using x, y, ...)
Build and Run
make
make test #(optional)
./axiom {source1.lisp, source2.lisp, ...}
Atoms are instantiated on first use. Case is ignored.