picrin/piclib/built-in.scm

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2013-10-28 13:50:12 -04:00
(define (zero? n)
(= n 0))
(define (positive? x)
(> x 0))
(define (negative? x)
(< x 0))
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(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)))
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(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))))
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(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)))
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(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)))))