map -package:containers -package:basement -package:psqueues -package:aeson -package:blaze-html -package:monoidal-containers -package:imports -package:regex-tdfa -package:bytestring -package:charset -package:os-string -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