29 lines
728 B
Scheme
29 lines
728 B
Scheme
|
#!/usr/bin/env scheme-script
|
||
|
|
|
||
|
|
(import (ikarus) (match))
|
||
|
|
|
||
|
|
(define (constant? x)
|
||
|
|
(or (number? x) (char? x) (string? x) (boolean? x)))
|
||
|
|
|
||
|
|
(define (ee x)
|
||
|
|
(define (ee x env)
|
||
|
|
(trace-match foo x
|
||
|
|
[,c (guard (constant? c)) c]
|
||
|
|
[,x (guard (symbol? x))
|
||
|
|
(cond
|
||
|
|
((assq x env) => cdr)
|
||
|
|
(else (error 'ee "unbound variable" x)))]
|
||
|
|
;[(let ([,x* ,v*] ...) ,b)
|
||
|
|
; (ee b (append (map cons x* (map (lambda (x) (ee x env)) v*)) env))]
|
||
|
|
[(let ([,x* ,[v*]] ...) ,b)
|
||
|
|
(ee b (append (map cons x* v*) env))]
|
||
|
|
[(+ ,[x] ,[y]) (+ x y)]
|
||
|
|
[,others (error 'ee "invalid expression" others)]))
|
||
|
|
(ee x '()))
|
||
|
|
|
||
|
|
(pretty-print
|
||
|
|
(ee '(let ((x 5)) (let ((y (+ x x))) (+ y x)))))
|
||
|
|
|
||
|
|
;(new-cafe ee)
|
||
|
|
|