map -package:containers -package:bytestring -package:incipit-base -package:blaze-html -package:basement -package:case-insensitive -package:charset -package:psqueues -package:regex-tdfa is:exact -package:base-compat -package:amazonka-core -package:monoidal-containers -package:invertible -package:insert-ordered-containers package:pipes

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

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