map -package:containers -package:bytestring -package:dlist -package:aeson -package:psqueues -package:Cabal-syntax -package:hedgehog -package:os-string -package:case-insensitive -package:monoidal-containers -package:invertible is:exact package:pipes

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

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