map -package:containers is:exact -package:case-insensitive -package:amazonka-core -package:conduit -package:insert-ordered-containers -package:blaze-html -package:incipit-base -package:charset -package:base-prelude -package:os-string package:pipes

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

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