From bc76b21859bceb63cc4bdf431141297071fd9ca2 Mon Sep 17 00:00:00 2001
From: Janus Troelsen <janus@flipstone.com>
Date: Fri, 23 Feb 2024 12:26:55 -0600
Subject: [PATCH] Add nominal role annotation for TaggedUnion

---
 src/Shrubbery/TaggedUnion.hs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/Shrubbery/TaggedUnion.hs b/src/Shrubbery/TaggedUnion.hs
index 8a3747b..c80721a 100644
--- a/src/Shrubbery/TaggedUnion.hs
+++ b/src/Shrubbery/TaggedUnion.hs
@@ -1,6 +1,7 @@
 {-# LANGUAGE AllowAmbiguousTypes #-}
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE RoleAnnotations #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE TypeOperators #-}
@@ -40,6 +41,8 @@ import Shrubbery.Union (Union, dissectUnion)
 newtype TaggedUnion (taggedTypes :: [Tag])
   = TaggedUnion (Union (TaggedTypes taggedTypes))
 
+type role TaggedUnion nominal
+
 instance
   ( TaggedTypes taggedTypes ~ types
   , ShowBranches types