From 13f361a606bdd78dde1dcf9ce3d046b57023e1d4 Mon Sep 17 00:00:00 2001
From: Adithya Kumar <adithya@composewell.com>
Date: Tue, 16 Nov 2021 12:44:55 +0530
Subject: [PATCH] Add back the Monad constraint in mergeBy

---
 src/Streamly/Internal/Data/Stream/IsStream/Expand.hs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/Streamly/Internal/Data/Stream/IsStream/Expand.hs b/src/Streamly/Internal/Data/Stream/IsStream/Expand.hs
index 998e1c587..72b6f9aab 100644
--- a/src/Streamly/Internal/Data/Stream/IsStream/Expand.hs
+++ b/src/Streamly/Internal/Data/Stream/IsStream/Expand.hs
@@ -707,7 +707,8 @@ zipAsyncWith f = zipAsyncWithM (\a b -> return (f a b))
 --
 -- @since 0.6.0
 {-# INLINE mergeBy #-}
-mergeBy :: IsStream t => (a -> a -> Ordering) -> t m a -> t m a -> t m a
+mergeBy ::
+       (IsStream t, Monad m) => (a -> a -> Ordering) -> t m a -> t m a -> t m a
 mergeBy f m1 m2 = fromStream $ K.mergeBy f (toStream m1) (toStream m2)
 
 -- | Like 'mergeBy' but with a monadic comparison function.