89 lines
1.5 KiB
Scheme
89 lines
1.5 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
|
|
(lambda (bindings . body)
|
|
(cons (cons 'lambda (cons (map car bindings) body)) (map cadr bindings))))
|