[Haskell-cafe] Re: More mystery with existentials and fundeps

On Mon, May 14, 2007 at 12:47:02PM +0100, Matthew Sackman wrote:

...

{-# OPTIONS_GHC -fglasgow-exts #-}

class F a b | b -> a where

data G :: * -> * where GC :: (F a b) => a -> G b

foo :: (F a b) => G b -> a foo g = case g of (GC a) -> a

And just to confirm, this is both with ghc 6.6 and with today's HEAD. Matthew -- Matthew Sackman http://www.wellquite.org/