map -package:base-prelude -package:basement -package:incipit-base -package:base-compat -package:dense-linear-algebra -is:exact -package:amazonka-core -package:hedgehog -package:aeson -package:dlist -package:blaze-html -package:bytestring -package:invertible -package:conduit package:pipes is:exact

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

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