Haddock is very cool idea. I like it, but I see that Haddock doesn't support existencial and universal quntified types. Is it too difficult to implement that? I want to rewrite Object I/O documentation but I need support for these features. I'll volunteer to extend Haddock if there isn't any who already work about that.

I've just added support for existential quantifiers in datatype declarations. You should find that Haddock already supports universals - in fact it allows 'forall' in exactly the same places as GHC (i.e. virtually everywhere). Cheers, Simon