map -package:containers -package:bytestring -package:foldl -package:invertible -package:ghc -package:Cabal-syntax -package:monoidal-containers -package:integration -package:base-compat-batteries -package:conduit -package:filepath package:pipes is:exact

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

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