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