map -package:containers -package:charset -package:case-insensitive -package:ghc -package:insert-ordered-containers -package:basement -package:psqueues -package:pipes -package:hedgehog -package:regex-tdfa -package:os-string -package:base-compat-batteries -package:blaze-html -package:vector package:vector-stream

Map a function over a Stream
Map a monadic function over a Stream
Execute a monadic action for each element of the Stream
Apply monadic function to each element and drop all Nothings