map -package:containers -package:Cabal-syntax -package:basement -package:psqueues -package:monoidal-containers -package:bytestring -package:charset -package:os-string -is:exact -package:conduit -package:text -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