[racket] Reversing strings (Jay's article)

I collect garbage three times to find finalized resources and free them. I
don't know if this is always necessary or if 3 is the right number, but I
learned to do it long ago and do it by habit.

Jay


On Wed, Oct 2, 2013 at 11:28 AM, Vlad Kozin <vladilen.kozin at gmail.com>wrote:

> Mostly a question to Jay McCarthy but I suppose could be interesting to
> others. Was going over his Reversing strings<http://jeapostrophe.github.io/2013-08-19-reverse-post.html> article.
> Somehow I get weird performance. Slowest solution turns out fastest,
> medium, fast and really fast are only marginally different.
>
> Could anyone have a look https://github.com/vkz/warm-up
> reverse-string.rkt has the solutions
> test-reverse-string.rkt does the performance check
> Testing it on 40'000 randomly generated strings 1000 chars each.
>
> While we're at it, why do we garbage-collect thrice here?
> let-values<http://docs.racket-lang.org/reference/let.html#%28form._%28%28quote._~23~25kernel%29._let-values%29%29>
>  ([(as cpu real gc) (time-apply<http://docs.racket-lang.org/reference/time.html#%28def._%28%28quote._~23~25kernel%29._time-apply%29%29>
>  (λ<http://docs.racket-lang.org/reference/lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._~ce~bb%29%29>
>  () exp<http://docs.racket-lang.org/reference/generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._exp%29%29>
> ) empty<http://docs.racket-lang.org/reference/pairs.html#%28def._%28%28lib._racket%2Flist..rkt%29._empty%29%29>
> )])    (collect-garbage<http://docs.racket-lang.org/reference/garbagecollection.html#%28def._%28%28quote._~23~25kernel%29._collect-garbage%29%29>
> ) (collect-garbage<http://docs.racket-lang.org/reference/garbagecollection.html#%28def._%28%28quote._~23~25kernel%29._collect-garbage%29%29>
> ) (collect-garbage<http://docs.racket-lang.org/reference/garbagecollection.html#%28def._%28%28quote._~23~25kernel%29._collect-garbage%29%29>
> )
>
> Thanks!
> ---
> Vlad Kozin <vladilen.kozin at gmail.com>
>
>
>
>
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-- 
Jay McCarthy <jay at cs.byu.edu>
Assistant Professor / Brigham Young University
http://faculty.cs.byu.edu/~jay

"The glory of God is Intelligence" - D&C 93
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