26 lines
721 B
Plaintext
26 lines
721 B
Plaintext
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(define (equal a b)
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(if (and (consp a) (consp b))
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(and (equal (car a) (car b))
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(equal (cdr a) (cdr b)))
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(eq a b)))
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; compare imposes an ordering on all values. yields -1 for a<b,
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; 0 for a==b, and 1 for a>b. lists are compared up to the first
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; point of difference.
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(defun compare (a b)
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(cond ((eq a b) 0)
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((or (atom a) (atom b)) (if (< a b) -1 1))
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(T (let ((c (compare (car a) (car b))))
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(if (not (eq c 0))
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c
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(compare (cdr a) (cdr b)))))))
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(defun length (l)
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(if (null l) 0
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(+ 1 (length (cdr l)))))
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(define (assoc item lst)
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(cond ((atom lst) ())
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((eq (caar lst) item) (car lst))
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(T (assoc item (cdr lst)))))
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