Sometimes it takes a while, but we get there eventually...
Graeme Moss <[EMAIL PROTECTED]> writes:
> (Usual apologies if this has been noted/solved since 2.05.)
>
> The following program (which sums [1..n] by brute force):
>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> import System(getArgs)
>
> data Test = Test !Int
>
> f :: Test -> Int -> Test
> f (Test n) i = Test (n+i)
>
> g :: Test -> Int
> g (Test n) = n
>
> sfoldl :: Eval a => (a -> b -> a) -> a -> [b] -> a
> sfoldl f z [] = z
> sfoldl f z (x:xs) = sfoldl f fzx (fzx `seq` xs)
> where fzx = f z x
>
> main = do argv <- getArgs
> print (g (sfoldl f (Test 0) [1..(read (argv!!0))]))
> <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
>
> blows the heap up when compiled with GHC, but not with HBC or Hugs.
This is a space leak related to the overloading on sfoldl in
conjunction with polymorphic recursion. The patch is too big to post
here, but will be in the next release.
Workaround: specialise sfoldl, or comment-out the type signature.
Cheers,
Simon
--
Simon Marlow [EMAIL PROTECTED]
University of Glasgow http://www.dcs.gla.ac.uk/~simonm/
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