Ubik
A small Scheme interpreter and compiler, written in OCaml, for illustrative purposes.
Programs are of the form:
<prog> ::= <defn>* <expr>
<defn> ::= (define <id> <expr>)
| (define (<id>+) <expr>)
| (struct <id> (<id>*))
<expr> ::= <int>
| #t
| #f
| <id>
| (<expr>+)
| (lambda (<id>*) <expr>)
| (if <expr> <expr> <expr>)
| (match <expr> (<pat> <expr>)*)
<pat> ::= (<id>+)
The implementation supports: arbitrary precision integers, higher-order functions, structures, simple pattern matching, some arithmetic operations (+, add1, sub1, =, expt), and list operations (list, cons, car, cdr, null, null?, pair?).
To build and run:
make
./ubik