map -package:containers -package:dlist -package:conduit -package:basement -package:bytestring -package:incipit-base -package:psqueues -package:os-string -package:regex-tdfa -package:filepath -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