Matthias Felleisen <matthias-1vnkwvzi4qavc3sceru...@public.gmane.org>
writes:
> CODE:
>
> #lang racket
>
> (define-syntax U
> (syntax-rules ()
> [(_ f) (f f)]))
>
> (define-syntax define/comb
> (syntax-rules ()
> [(_ comb name (arg1 arg2) body)
> (define name
> (comb (λ (name) (λ (arg1 arg2) body))))]))
>
> (define (Z f)
> (U (λ (g) (λ (x y) ((f (U g)) x y)))))
>
> (define/comb Z comb-sum (l t)
> (if (empty? l) t (comb-sum (rest l) (+ t (first l)))))
>
> (define (sum l t)
> (if (empty? l) t (sum (rest l) (+ t (first l)))))
>
> (collect-garbage)(collect-garbage)
> (time (comb-sum (make-list 10000000 1) 0))
>
> (collect-garbage)(collect-garbage)
> (time (sum (make-list 10000000 1) 0))
Why are the `collect-garbage' calls doubled?
Štěpán
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