Expose CrossStream and it's smart constructors

Author: adithyaov

core/src/Streamly/Data/Stream.hs

@@ -81,6 +81,11 @@ module Streamly.Data.Stream
     -- * The Stream Type
       Stream
 
+    -- * CrossStream
+    , CrossStream
+    , unCross
+    , mkCross
+
     -- * Construction
     -- | Functions ending in the general shape @b -> Stream m a@.
     --