map -package:conduit -is:exact -package:containers -package:basement -package:case-insensitive -package:hedgehog -package:monoidal-containers -package:insert-ordered-containers -package:invertible -package:regex-tdfa -package:text -package:Cabal-syntax is:exact package:pipes

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

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