50 lines
1.3 KiB
Scheme
50 lines
1.3 KiB
Scheme
;;; NTAKL -- The TAKeuchi function using lists as counters,
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;;; with an alternative boolean expression.
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(library (r6rs-benchmarks ntakl)
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(export main)
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(import (r6rs) (r6rs-benchmarks))
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(define (listn n)
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(if (= n 0)
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'()
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(cons n (listn (- n 1)))))
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(define l18 (listn 18))
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(define l12 (listn 12))
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(define l6 (listn 6))
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(define (mas x y z)
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(if (not (shorterp y x))
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z
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(mas (mas (cdr x) y z)
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(mas (cdr y) z x)
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(mas (cdr z) x y))))
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; Part of the fun of this benchmark is seeing how well the compiler
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; can understand this ridiculous code, which dates back to the original
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; Common Lisp. So it probably isn't a good idea to improve upon it.
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#;
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(define (shorterp x y)
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(and (not (null? y))
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(or (null? x)
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(shorterp (cdr x)
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(cdr y)))))
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; But SML/NJ runs this benchmark about 15 times as fast when the
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; code above is rewritten as follows, so I tried it for Scheme also.
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(define (shorterp x y)
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(cond ((null? y) #f)
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((null? x) #t)
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(else
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(shorterp (cdr x) (cdr y)))))
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(define (main . args)
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(run-benchmark
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"ntakl"
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takl-iters
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(lambda (result) (equal? result '(7 6 5 4 3 2 1)))
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(lambda () (lambda () (mas l18 l12 l6))))))
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