From b05799dc0937e48fd7efa063bf794f9e4f56d564 Mon Sep 17 00:00:00 2001
From: Owen Shepherd <414owen@gmail.com>
Date: Wed, 8 Jan 2020 14:48:41 +0000
Subject: [PATCH] added semigroup constraint

---
 src/Reflex/Patch/DMapWithReset.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Reflex/Patch/DMapWithReset.hs b/src/Reflex/Patch/DMapWithReset.hs
index b8bb7f31..8ad4ced5 100644
--- a/src/Reflex/Patch/DMapWithReset.hs
+++ b/src/Reflex/Patch/DMapWithReset.hs
@@ -41,7 +41,7 @@ instance (Semigroup (p a), Patch (p a)) => Semigroup (By p a) where
   By_Patch x <> By_Patch y = By_Patch (x <> y)
   By_Patch _ <> By_Delete = By_Delete
 
-instance (Monoid (p a), Patch (p a)) => Monoid (By p a) where
+instance (Semigroup (p a), Monoid (p a), Patch (p a)) => Monoid (By p a) where
   mappend = (<>)
   mempty = By_Patch mempty