[Haskell-cafe] fast image processing in haskell?

[Jeff Briggs]

On 06/08/06, Bulat Ziganshin <bulat.ziganshin at gmail.com> wrote:
> more used than average lib. btw, is it possible to rewrite this
> algorithm in more high-level way using FPS, of course with more or
> less good speed?

Using Data.ByteString, I see no noticeable decrease in performance.

data C = R|G|B deriving Show
...
         B.useAsCStringLen image $ \ (src,len) ->
             copyBytes dst (castPtr src) len
         print $ B.foldl sum_rgb (0,0,0,R) image
...
sum_rgb (r,g,b,s) px
    = r `seq` g `seq` b `seq` case s of
        R -> (r+px, g,    b,    G)
        G -> (r,    g+px, b,    B)
        _ -> (r,    g,    b+px, R)

Fantastic library.