127 lines
2.4 KiB
Scheme
127 lines
2.4 KiB
Scheme
; Although looking like a magic, it works nice.
|
|
(define (car x) (car x))
|
|
(define (cdr x) (cdr x))
|
|
|
|
(define (zero? n)
|
|
(= n 0))
|
|
|
|
(define (positive? x)
|
|
(> x 0))
|
|
|
|
(define (negative? x)
|
|
(< x 0))
|
|
|
|
(define (caar p)
|
|
(car (car p)))
|
|
|
|
(define (cadr p)
|
|
(car (cdr p)))
|
|
|
|
(define (cdar p)
|
|
(cdr (car p)))
|
|
|
|
(define (cddr p)
|
|
(cdr (cdr p)))
|
|
|
|
(define (list . args)
|
|
args)
|
|
|
|
(define (list? obj)
|
|
(if (null? obj)
|
|
#t
|
|
(if (pair? obj)
|
|
(list? (cdr obj))
|
|
#f)))
|
|
|
|
(define (make-list k . args)
|
|
(if (null? args)
|
|
(make-list k #f)
|
|
(if (zero? k)
|
|
'()
|
|
(cons (car args)
|
|
(make-list (- k 1) (car args))))))
|
|
|
|
(define (length list)
|
|
(if (null? list)
|
|
0
|
|
(+ 1 (length (cdr list)))))
|
|
|
|
(define (append xs ys)
|
|
(if (null? xs)
|
|
ys
|
|
(cons (car xs)
|
|
(append (cdr xs) ys))))
|
|
|
|
(define (reverse list . args)
|
|
(if (null? args)
|
|
(reverse list '())
|
|
(if (null? list)
|
|
(car args)
|
|
(reverse (cdr list)
|
|
(cons (car list) (car args))))))
|
|
|
|
(define (list-tail list k)
|
|
(if (zero? k)
|
|
list
|
|
(list-tail (cdr list) (- k 1))))
|
|
|
|
(define (list-ref list k)
|
|
(car (list-tail list k)))
|
|
|
|
(define (list-set! list k obj)
|
|
(set-car! (list-tail list k) obj))
|
|
|
|
(define (list-copy obj)
|
|
(if (null? obj)
|
|
obj
|
|
(cons (car obj)
|
|
(list-copy (cdr obj)))))
|
|
|
|
(define (map f list)
|
|
(if (null? list)
|
|
'()
|
|
(cons (f (car list))
|
|
(map f (cdr list)))))
|
|
|
|
(define-macro (let bindings . body)
|
|
(cons (cons 'lambda (cons (map car bindings) body))
|
|
(map cadr bindings)))
|
|
|
|
(define-macro (cond . clauses)
|
|
(if (null? clauses)
|
|
#f
|
|
(let ((c (car clauses)))
|
|
(let ((test (car c))
|
|
(if-true (cons 'begin (cdr c)))
|
|
(if-false (cons 'cond (cdr clauses))))
|
|
(list 'if test if-true if-false)))))
|
|
|
|
(define-macro (and . exprs)
|
|
(if (null? exprs)
|
|
#t
|
|
(let ((test (car exprs))
|
|
(if-true (cons 'and (cdr exprs))))
|
|
(list 'if test if-true #f))))
|
|
|
|
(define-macro (or . exprs)
|
|
(if (null? exprs)
|
|
#f
|
|
(let ((test (car exprs))
|
|
(if-false (cons 'or (cdr exprs))))
|
|
(list 'let (list (list 'it test))
|
|
(list 'if 'it 'it if-false)))))
|
|
|
|
(define-macro (quasiquote x)
|
|
(cond
|
|
((symbol? x) (list 'quote x))
|
|
((pair? x)
|
|
(cond
|
|
((eq? 'unquote (car x)) (cadr x))
|
|
((and (pair? (car x))
|
|
(eq? 'unquote-splicing (caar x)))
|
|
(list 'append (cadr (car x)) (list 'quasiquote (cdr x))))
|
|
(#t (list 'cons
|
|
(list 'quasiquote (car x))
|
|
(list 'quasiquote (cdr x))))))
|
|
(#t x)))
|