From 7b379c724999c4b415b1c3826db748450c7a6571 Mon Sep 17 00:00:00 2001
From: Adam Chlipala <adam@chlipala.net>
Date: Sun, 7 Feb 2016 20:41:34 -0500
Subject: Finish removing PWild; only load a library once, even if referenced
 multiple times in a .urp tree

---
 src/elaborate.sml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'src/elaborate.sml')

diff --git a/src/elaborate.sml b/src/elaborate.sml
index 9765b090..6965adfd 100644
--- a/src/elaborate.sml
+++ b/src/elaborate.sml
@@ -1565,7 +1565,7 @@ fun elabPat (pAll as (p, loc), (env, bound)) =
         case p of
             L.PVar x =>
             let
-                val t = if SS.member (bound, x) then
+                val t = if x <> "_" andalso SS.member (bound, x) then
                             (expError env (DuplicatePatternVariable (loc, x));
                              terror)
                         else
-- 
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