23 Mar
2007
23 Mar
'07
5:45 a.m.
Ok,
btw, this works :)
data Cnd c where
In :: (Eq (c a)) => c a -> [c a] -> Cnd c
check :: (Eq (c a)) => Cnd c -> Bool
check (x `In` items) = x `elem` items
That's nice :)
2007/3/23, Simon Peyton-Jones
| Interesting thing though, it's the same on 6.4.1. | | Wasn't this brokenness introduced in 6.6, but rather has lingered in | ghc for a while, or since the introduction of GADTs, at all?
No it's always been broken. I finally made GADTs and type classes work together in the HEAD a few months ago, using implication constraints for the first time.