@@ -424,7 +424,6 @@ mapMWithInput f (Unfold ustep uinject) = Unfold step inject
424424-- Convert streams into unfolds
425425-------------------------------------------------------------------------------
426426
427−-- this is horribly slow
428427{-# INLINE_NORMAL fromStreamD #-}
429428fromStreamD :: Monad m => Unfold m (Stream m a) a
430429fromStreamD = Unfold step return
@@ -451,6 +450,9 @@ fromStreamK = Unfold step return
451450 Just (x, xs) -> Yield x xs
452451 Nothing -> Stop
453452
453+-- XXX Using Unfold.fromStreamD seems to be faster (using cross product test
454+-- case) than using fromStream even if it is implemented using fromStreamD.
455+--
454456-- | Convert a stream into an 'Unfold'. Note that a stream converted to an
455457-- 'Unfold' may not be as efficient as an 'Unfold' in some situations.
456458--