generic default instances: left bias in sum types

mauke · Oct 21, 2024 · 81e576d · 81e576d
1 parent cd9d5cf
commit 81e576d
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/Data/Default.hs b/Data/Default.hs
@@ -84,6 +84,9 @@ instance (Default a) => GDefault (K1 i a) where
 instance (GDefault a, GDefault b) => GDefault (a :*: b) where
     gdef = gdef :*: gdef
 
+instance (GDefault a) => GDefault (a :+: b) where
+    gdef = L1 gdef
+
 instance (GDefault a) => GDefault (M1 i c a) where
     gdef = M1 gdef