Hi, I updated base-compat[1] for the recent AMP/Foldable/Traversable changes and base-4.8.0.0. A new version 0.6.0 is on Hackage. The purpose of base-compat is to provide a way to write code that works with multiple versions of GHC without the need for CPP. The idea is to have .Compat modules (e.g. Control.Exception.Compat) that provide the same interface across all supported versions of GHC (we test GHC 7.* on travis and I test 6.12.3 manually). The main focus of this release is to make Prelude.Compat as complete as possible to help with the AMP/Foldable/Traversable transition. Prelude.Compat now exposes the exact same interface as Prelude from base-4.8.0.0. It can be used together with -XNoImplicitPrelude to write code that works with all supported versions of GHC, e.g.: {-# LANGUAGE NoImplicitPrelude #-} import Prelude.Compat main :: IO () main = mapM_ print (Just 23) Prelude.Compat is complete and we have tests that ensure that the interface is the same for all supported versions of GHC. But other modules still need more work. In the past base-compat did not get the love it deserves, but I'm committed to put more effort into it and make it as complete as possible. Any help with that effort would be greatly appreciated. If you want to help, please open issues and pull requests on GitHub, or send me feedback by email or on IRC (solirc on Freenode). Cheers, Simon [1] http://hackage.haskell.org/package/base-compat