map -package:containers -package:ghc -package:base-compat -package:invertible -package:integration -package:foldl -package:amazonka-core -package:Cabal-syntax -package:base-prelude -package:basement -package:base-compat-batteries package:pipes is:exact

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

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