Why my list function eats memory? - comp.lang.haskell

Допис з розмови Why my list function eats memory?

Paul Graphov

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Більше налаштувань 30 Вер 2008, 22:35

Групи новин: comp.lang.haskell

Від: Paul Graphov <grap...@gmail.com>

Дата: Tue, 30 Sep 2008 12:35:15 -0700 (PDT)

Локально: Вт 30 Вер 2008 22:35

Тема: Re: Why my list function eats memory?

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> No, because the drop's are shared. Or are you for some reason trying
> to evaluate the last element first when using the result (see below)?

Yes, I just used "!! 1000000" on it while testing.
If I print all million elements no stack overflow occurs.
It seems that this was the reason that programs behaved different
ways.

> > And "takeWhile (not . null)" actually pattern matches them against
> > "[]" so they are forced to be calculated.

> But that evaluation will stop after it encounters the first cons,
> so it will leave a chunk like "y : (take (n-1) x (drop (d-1) ...))".
> Hence that cannot be the reason.

Hmmm... It seems to me to get first cons one must remove ALL drops?
You cannot check if (drop d (drop d(..............)) is nul until you
unwind all drops...
Thanks.

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