Forward port to nightly-2018-06-22.

1 files changed, 8 insertions, 4 deletions

diff --git a/src/Crypto/Tox.hs b/src/Crypto/Tox.hs
index d1992967..a1741a1f 100644
--- a/src/Crypto/Tox.hs
+++ b/src/Crypto/Tox.hs
@@ -83,6 +83,7 @@ import GHC.Exts (Constraint)
 #endif
 import Data.Ord
 import Data.Serialize as S
+import Data.Semigroup
 import Data.Word
 import Foreign.Marshal.Alloc
 import Foreign.Ptr
@@ -159,11 +160,14 @@ instance Contravariant Size where
       ConstSize n -> ConstSize n
       VarSize g   -> VarSize (\x -> g (f x))
 
+instance Semigroup (Size a) where
+    ConstSize x <> ConstSize y = ConstSize (x + y)
+    VarSize f   <> ConstSize y = VarSize $ \x -> f x + y
+    ConstSize x <> VarSize g   = VarSize $ \y -> x + g y
+    VarSize f   <> VarSize g   = VarSize $ \x -> f x + g x
+
 instance Monoid (Size a) where
-    ConstSize x `mappend` ConstSize y = ConstSize (x + y)
-    VarSize f   `mappend` ConstSize y = VarSize $ \x -> f x + y
-    ConstSize x `mappend` VarSize g   = VarSize $ \y -> x + g y
-    VarSize f   `mappend` VarSize g   = VarSize $ \x -> f x + g x
+    mappend = (<>)
     mempty = ConstSize 0