Yes, thanks, I've seen this; why can't cabal find the package? Is the fact that it is filed under "archive" an indicator?! I have tried Control.Bifunctor, and also Control.Categorical.Bifunctor, and Data.Bifunctor. Certainly it is an easy thing to define myself, but I'm both trying to be minimalistic, and to understand what failed. ------------------------------------------- From: Clark Gaebel [mailto:cgaebel@uwaterloo.ca] Sent: Wednesday, December 12, 2012 3:12 PM Subject: Re: [Haskell-cafe] Control.bimap? http://hackage.haskell.org/packages/archive/categories/0.59/doc/html/Control... . And found a nicer approach: (ns,ne) = (nub***nub) unzip g Or perhaps: (ns.ne) = bimap nub nub $ unzip g -- from Control.Bifunctor The SO reference I saw described bimap as a way to map a function over a pair, and it seemed like a great match, but I cannot find the bimap function, and cabal reports no package Control.Bifunctor. ??