map -package:containers -package:case-insensitive -package:dlist -package:Cabal-syntax -package:charset -package:blaze-html -package:imports -package:filepath -package:conduit -package:ghc -package:hedgehog -package:os-string -package:regex-tdfa package:pipes is:exact

Apply a function to all values flowing downstream
map id = cat

map (g . f) = map f >-> map g