RE: Proposal: Foldable typeclass: make foldl' and foldr' class methods

It's a pity to have to add methods to get around GHC's limitations, but it seems harmless. Looks like you'll want strict versions of all 5 methods, though.

The only potential breakage is that foldl' and foldr' are exported via Foldable(..) rather than directly. This could affect modules that use explicit imports.

I don't think so. You can import methods separately.