Keith Wansbrough wrote:
> Surely it would be better to split the one stream into several infinite ones:
>
> splitStream :: [a] -> ([a],[a])
>
> splitStream xs = unzip (spl xs)
> where spl (x:y:xs) = (x,y):(spl xs)
>
> Then you don't have to know how many you are going to use from each stream.
If I'm not mistaken, this definition has the danger of a space leak:
Suppose you initially use a lot of elements of the first list/stream
only and then elements from the second, e.g.:
foo :: Int -> IO ()
foo n = do print . head . drop n $ xs
print . head $ ys
where (xs,ys) = splitStream (repeat 1)
This gives you space usage linear in n... :-(
Cheers,
Sven
--
Sven Panne Tel.: +49/89/2178-2235
LMU, Institut fuer Informatik FAX : +49/89/2178-2211
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