error "generalize fmap" = map ==> fmap -- AMP fallout error "generalize mapM" = mapM ==> traverse error "generalize mapM_" = mapM_ ==> traverse_ error "generalize forM" = forM ==> for error "generalize forM_" = forM_ ==> for_ error "Avoid return" = return ==> pure where note = "return is obsolete as of GHC 7.10" error "use pure" = free . Pure ==> pure error "use extract" = headF . runCofree ==> extract