In article <[EMAIL PROTECTED]>, Ross Paterson <[EMAIL PROTECTED]> wrote:
> As it happens, I would like yet another intermediate class: > > class BiFunctor a where > bimap :: (b' -> b) -> (c -> c') -> a b c -> a b' c' This can be decomposed into: fmap :: (c -> c') -> a b c -> a b c' cofmap2 :: (b' -> b) -> a b c -> a b' c bimap :: (Cofunctor2 a,Functor (a b)) => (b' -> b) -> (c -> c') -> a b c -> a b' c' bimap bb cc = (cofmap2 bb) . (fmap cc) It would be nice to be able to write this: class (Cofunctor2 a,forall b. Functor (a b)) => BiFunctor a instance (Cofunctor2 a,forall b. Functor (a b)) => BiFunctor a Unfortunately, foralls are not allowed in class or instance contexts... -- Ashley Yakeley, Seattle WA _______________________________________________ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
