75 lines
1.2 KiB
Scheme
75 lines
1.2 KiB
Scheme
(define (zero? n)
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(= n 0))
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(define (positive? x)
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(> x 0))
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(define (negative? x)
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(< x 0))
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(define (caar p)
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(car (car p)))
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(define (cadr p)
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(car (cdr p)))
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(define (cdar p)
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(cdr (car p)))
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(define (cddr p)
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(cdr (cdr p)))
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(define (list . args)
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args)
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(define (list? obj)
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(if (null? obj)
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#t
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(if (pair? obj)
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(list? (cdr obj))
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#f)))
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(define (make-list k . args)
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(if (null? args)
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(make-list k #f)
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(if (zero? k)
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'()
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(cons (car args)
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(make-list (- k 1) (car args))))))
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(define (length list)
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(if (null? list)
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0
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(+ 1 (length (cdr list)))))
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(define (append xs ys)
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(if (null? xs)
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ys
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(cons (car xs)
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(append (cdr xs) ys))))
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(define (reverse list . args)
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(if (null? args)
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(reverse list '())
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(if (null? list)
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(car args)
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(reverse (cdr list)
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(cons (car list) (car args))))))
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(define (list-tail list k)
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(if (zero? k)
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list
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(list-tail (cdr list) (- k 1))))
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(define (list-ref list k)
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(car (list-tail list k)))
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(define (list-set! list k obj)
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(set-car! (list-tail list k) obj))
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(define (list-copy obj)
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(if (null? obj)
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obj
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(cons (car obj)
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(list-copy (cdr obj)))))
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