On 29 December 2010 16:17, Mario Blažević
The best place according to the "unambiguously recommended and easy to find" criteria is the base library. The next best would be a Hackage library with minimal dependencies, whose name exactly corresponds to the class - contrafunctor or control-contrafunctor, for example.
Personally, I'm at best lukewarm about minimal Hackage-hosted packages for Base-like things. As Cabal dependencies are on version numbers rather than capability (c.f. autoconf) I see them as much a cost as a benefit, so I don't want to depend on things that aren't doing some functional work. Would a "Base 2" or "BaseExts" library that amalgamates the "less central" structures like Comonad, Bifunctor, Semigroup, ... have value to the community?