map is:exact -package:text -package:Cabal-syntax -package:containers -package:base-compat-batteries -package:dlist -package:basement -package:foldl -package:hedgehog -package:monoidal-containers -package:blaze-html -package:base-compat package:pipes

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

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