map -package:containers -package:base -package:insert-ordered-containers -package:incipit-base -package:conduit -package:base-prelude -package:blaze-html -package:invertible -package:bytestring -package:charset -package:foldl package:pipes is:exact

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

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