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Minor for-each speedup

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* module/ice-9/boot-9.scm (for-each): Minor speedup by unrolling
  tortoise/hare loop.
This commit is contained in:
Andy Wingo 2014-01-28 22:28:08 +01:00
parent 024a60e374
commit 8dcabf6003
1 changed files with 10 additions and 11 deletions
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19
module/ice-9/boot-9.scm
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@ -840,19 +840,18 @@ information is unavailable."
(define for-each
(case-lambda
((f l)
(let for-each1 ((hare l) (tortoise l) (move? #f))
(let for-each1 ((hare l) (tortoise l))
(if (pair? hare)
(if move?
(if (eq? tortoise hare)
(begin
(f (car hare))
(let ((hare (cdr hare)))
(if (pair? hare)
(begin
(when (eq? tortoise hare)
(scm-error 'wrong-type-arg "for-each" "Circular list: ~S"
(list l) #f)
(begin
(list l) #f))
(f (car hare))
(for-each1 (cdr hare) (cdr tortoise) #f)))
(begin
(f (car hare))
(for-each1 (cdr hare) tortoise #t)))
(for-each1 (cdr hare) (cdr tortoise))))))
(if (not (null? hare))
(scm-error 'wrong-type-arg "for-each" "Not a list: ~S"
(list l) #f)))))