map -package:containers -package:Cabal-syntax -is:exact -package:base-compat-batteries is:exact -package:incipit-base -package:bytestring -package:basement -package:os-string -package:monoidal-containers -package:base-compat package:pipes

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

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