map -package:containers -package:blaze-html -package:bytestring -package:conduit -package:invertible -package:case-insensitive -package:filepath -package:basement -package:integration package:base is:exact

map f xs is the list obtained by applying f to each element of xs, i.e.,
map f [x1, x2, ..., xn] == [f x1, f x2, ..., f xn]
map f [x1, x2, ...] == [f x1, f x2, ...]
>>> map (+1) [1, 2, 3]
[2,3,4]
Map a function over a NonEmpty stream.