[Haskell-beginners] reverse [1..]

[Jonathan Rioux]

Hello Emanuel,

Here's the excerpt of the "reverse" function in GHC-List   (

-- | 'reverse' @xs@ returns the elements of @xs@ in reverse order.--
@xs@ must be finite.reverse                 :: [a] -> [a]#ifdef
USE_REPORT_PRELUDEreverse                 =  foldl (flip (:))
[]#elsereverse l =  rev l []  where    rev []     a = a    rev (x:xs)
a = rev xs (x:a)#endif

Reversing an infinite list, Haskell will try to reach the end of the
list until it runs out of memory.
I don't thing it's doable lazily.




On Tue, Dec 18, 2012 at 9:24 AM, Emanuel Koczwara <poczta at emanuelkoczwara.pl
> wrote:

> Hi,
>
>   When I run this code in ghci:
>
>     reverse [1..]
>
>   I get:
>
>     <interactive>: out of memory (requested 2097152 bytes)
>
>   Can anyone explain this behaviour?
>
> Emanuel
>
>
>
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