map -package:containers -package:basement -package:ghc -package:conduit -package:monoidal-containers -package:text -package:foldl -package:insert-ordered-containers -package:os-string -package:psqueues -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