From 5d4317031a859d025300bf213c162e9fffc9cd3a Mon Sep 17 00:00:00 2001
From: Rob Rix <robrix@github.com>
Date: Tue, 8 Oct 2019 15:41:16 -0400
Subject: [PATCH] :memo: the right-recursive instance.

---
 semantic-tags/src/AST/Element.hs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/semantic-tags/src/AST/Element.hs b/semantic-tags/src/AST/Element.hs
index ee1cb3ca1..cb50d8369 100644
--- a/semantic-tags/src/AST/Element.hs
+++ b/semantic-tags/src/AST/Element.hs
@@ -55,6 +55,7 @@ instance Element     t l
   prj' (L1 l) = prj l
   prj' _      = Nothing
 
+-- | Membership on the right.
 instance Element     t r
       => Element' 'R t (l :+: r) where
   prj' (R1 r) = prj r