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