map -package:containers -package:foldl -package:incipit-base -package:aeson -package:base-prelude -package:monoidal-containers -package:dense-linear-algebra -package:blaze-html -package:os-string -package:integration -package:base-compat is:exact package:pipes

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

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