map -package:base -is:exact -is:exact -package:unordered-containers -package:case-insensitive -package:bytestring -package:pipes -package:vector -package:blaze-html -package:io-streams package:streaming is:exact

Standard map on the elements of a stream.
>>> S.stdoutLn $ S.map reverse $ each (words "alpha beta")
ahpla
ateb