map -package:containers -package:base-compat-batteries -package:foldl -package:Cabal-syntax -package:dense-linear-algebra -package:insert-ordered-containers -package:base-prelude -package:blaze-html -package:basement -package:incipit-base package:pipes is:exact

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

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