Yes, with your modification, it works just fine in GHC, and I guess therefore hbc. Documentatino in the user manual. http://haskell.cs.yale.edu/ghc/ Simon | -----Original Message----- | From: Ashley Yakeley [mailto:ashley@semantic.org] | Sent: 14 March 2001 04:22 | To: Haskell List | Subject: Re: Contexts in Existential Types | | | At 2001-03-13 19:36, I wrote: | | >Would it be appropriate for Haskell to be able to remember | contexts in | >existential types? For instance, currently this does not | work in Hugs: | > | >-- | >class Charable a where | > obtainChar :: a -> Char | > | >instance Charable Char where | > obtainChar c = c | > | >data AnyCharable = forall c. (Charable c) => MkAnyCharable c | > | >anyA = MkAnyCharable 'a' | >recoverA = obtainChar ((\(MkAnyCharable c) -> c) anyA) | >-- | | Whoops, my error. It is possible to do this: | | -- | recoverA = (\(MkAnyCharable c) -> obtainChar c) anyA | -- | | Sorry... | | -- | Ashley Yakeley, Seattle WA | | | _______________________________________________ | Haskell mailing list | Haskell@haskell.org | http://www.haskell.org/mailman/listinfo/haskell |