map -package:containers -package:blaze-html -package:bytestring -package:conduit -package:base -package:aeson -package:imports -package:amazonka-core -package:ghc is:exact -package:basement -package:Cabal-syntax -package:base-prelude -package:filepath -package:base-compat package:pipes

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

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