Indeed. If you omit `in-range', this can have a big cost on performance on
nested loops (I observe almost a factor 10 on this small example).
Note that you can also write a nested for loop with `for*':
(for* ([i (in-range 10000)]
[j (in-range 1000)])
(void))
On Mon, Apr 2, 2018 at 10:33 AM, 若草春男 <whbug...@gmail.com> wrote:
> Thank you, Laurent.
>
> I mind the performance of in-range, but it seems to be no problem.
>
> #lang racket
>
> (time (for ([i (in-range 10000)])
> (for ([j (in-range 1000)])
> (void))))
>
> (time (do ([i 0 (+ i 1)]) ([= i 10000])
> (do ([j 0 (+ j 1)]) ([= j 1000])
> (void))))
>
> cpu time: 110 real time: 106 gc time: 0
> cpu time: 109 real time: 111 gc time: 0
>
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