map -package:dense-linear-algebra -is:exact -package:blaze-html -package:basement -is:exact -package:invertible is:exact -package:hedgehog -package:monoidal-containers -package:foldl -package:insert-ordered-containers -package:base-compat-batteries -package:imports -package:integration package:pipes

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

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