[Haskell-cafe] Re: ANNOUNCE: fixpoint 0.1

[redirecting from haskell@...] apfelmus wrote: [...]

I wonder whether a multi parameter type class without fundeps/associated types would be better.

class Fixpoint f t where inject :: f t -> t project :: t -> f t

[...]

Interestingly, this even gives slightly shorter type signatures

cata :: Fixpoint f t => (f s -> s) -> t -> s size :: (Fixpoint f t, Foldable f) => t -> Int

size can't be used now though, because there is no way to infer f. Bertram