Hi Eugene, did you try using the SPECIALIZE pragma? It is part of the Haskell 98 and Haskell 2010 specifications. On 02.11.2011, at 12:14, Eugene Kirpichov wrote:
Yay!!!
I made a small change in Types.chs and got my original cairo-binding-based program to be just as blazing fast. The only problem I have with this is that I used multiparameter type classes.
Dear gtk2hs team! Is it possible to incorporate my changes? I'm pretty sure people will be happy by an order-of-magnitude speedup. Probably the stuff could be wrapped in #define's for those who aren't using GHC and can't use multiparameter type classes?
I am pretty sure I could have done the same with rewrite rules, but I tried for a while and to no avail.
FAILED SOLUTION: rewrite rules cFloatConv :: (RealFloat a, RealFloat b) => a -> b cFloatConv = realToFrac {-# NOINLINE cFloatConv #-} {-# RULES "cFloatConv/float2Double" cFloatConv = float2Double #-} {-# RULES "cFloatConv/double2Float" cFloatConv = double2Float #-} {-# RULES "cFloatConv/self" cFloatConv = id #-}
See [1] in GHC User Guide. cFloatConv :: (RealFloat a, RealFloat b) => a -> b cFloatConv = realToFrac -- or try fromRational . toRational {-# SPECIALIZE cFloatConv :: Float -> Double #-} {-# SPECIALIZE cFloatConv :: Double -> Float #-} I did not try to compile or even benchmark this code. But I think it might help in your case. Cheers, Jean [1]: http://www.haskell.org/ghc/docs/latest/html/users_guide/pragmas.html#special...