could you please send the complete options/commandline and the expect final form of 'test'? i did play with Conal's example as well, but couldn't find a combination to make it work.
perhaps i'm looking at the wrong output, but it seems i either get non-inlined 'onInt's in various forms or multiple matches out of the same dictionary, but with generic method names rather than the original 'fromInt'/'toInt'.
claus
Thanks a million, Lennart! -fno-method-sharing was the missing piece. - Conal On Sat, Jun 7, 2008 at 5:07 AM, Lennart Augustsson <[EMAIL PROTECTED]> wrote:Here's something that actually works. You need to pass -fno-method-sharing on the command line. Instead of using rules on methods it uses rules on global functions, and these global functions don't get inlined until late (after the rule has fired). -- Lennart module F where -- | Domain of a linear map. class AsInt a where toInt' :: a -> Int fromInt' :: Int -> a {-# INLINE[1] toInt #-} toInt :: (AsInt a) => a -> Int toInt = toInt' {-# INLINE[1] fromInt #-} fromInt :: (AsInt a) => Int -> a fromInt = fromInt' {-# RULES "toInt/fromInt" forall m . toInt (fromInt m) = m #-} {-# INLINE onInt #-} onInt :: AsInt a => (Int -> Int) -> (a -> a) onInt f x = fromInt (f (toInt x)) test :: AsInt a => (Int -> Int) -> (Int -> Int) -> (a -> a) test h g = onInt h . onInt g 2008/6/7 Conal Elliott <[EMAIL PROTECTED]>: > I'm trying to do some fusion in ghc, and I'd greatly appreciate help with > the code below (which is simplified from fusion on linear maps). I've tried > every variation I can think of, and always something prevents the fusion. > > Help, please! Thanks, - Conal > > > {-# OPTIONS_GHC -O2 -Wall -fglasgow-exts -ddump-simpl -ddump-simpl-stats #-} > -- {-# OPTIONS_GHC -ddump-simpl-iterations #-} > > module F where > > -- | Domain of a linear map. > class AsInt a where > toInt :: a -> Int > fromInt :: Int -> a > > {-# RULES > "toInt/fromInt" forall m. toInt (fromInt m) = m > #-} > > {-# INLINE onInt #-} > onInt :: AsInt a => (Int -> Int) -> (a -> a) > onInt f = fromInt . f . toInt > > test :: AsInt a => (Int -> Int) -> (Int -> Int) -> (a -> a) > test h g = onInt h . onInt g > > -- The desired result: > -- > -- test h g > -- == onInt h . onInt g > -- == (fromInt . h . toInt) . (fromInt . g . toInt) > -- == \ a -> (fromInt . h . toInt) ((fromInt . g . toInt) a) > -- == \ a -> (fromInt . h . toInt) (fromInt (g (toInt a))) > -- == \ a -> fromInt (h (toInt (fromInt (g (toInt a))))) > -- == \ a -> fromInt (h (g (toInt a))) > > > > _______________________________________________ > Glasgow-haskell-users mailing list > Glasgow-haskell-users@haskell.org > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users > >
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