[Haskell-cafe] Re: Stack overflow

[Grzegorz]

Daniel McAllansmith <dm.maillists <at> gmail.com> writes:

> 
> On Friday 25 May 2007 06:50, Grzegorz wrote:
> > Hi all,
> > I have a simple piece of code which is giving me stack overflow. I guess I
> > need to make it stricter sowhere but I can't figure out extactly where. So
> > I thought I'd ask the experts.
> 
> I'm not sure.  A real expert from the list will probably tell you what the 
> cause of the overflow is.
> 
> As for finding the mean hamming distance, have you considered something like 
> the following:
> 
> hammingDistance xs ys = length (filter not (zipWith (==) xs ys))
> 
> meanHammingDistance xss yss = sumHDs / cntHDs
>     where
>         hds = map (uncurry hammingDistance) [(xs, ys) | xs <- xss, ys <- yss]
>         sumHDs = fromIntegral (sum hds)
>         cntHDs = fromIntegral (length hds)
> 

Originally I had something like that but it was very slow (approx 40 times
slower than calling out to C). Someone on #haskell advised me to manually
deforest the lists: the code I posted was my attempt at that. 
Thanks,
--
Grzegorz