From 417f27cc391971f15f36c2c5dcbb1ad962278ae5 Mon Sep 17 00:00:00 2001
From: Rob Rix <rob.rix@github.com>
Date: Thu, 19 Nov 2015 16:07:30 -0800
Subject: [PATCH] String/range pairs are ordered.

---
 src/Unified.hs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/Unified.hs b/src/Unified.hs
index a34396ecf..ed8380a14 100644
--- a/src/Unified.hs
+++ b/src/Unified.hs
@@ -34,3 +34,7 @@ range :: Patch (Term a Info) -> Maybe Range
 range patch = range . extract <$> after patch where
   extract (annotation :< _) = annotation
   range (Info range _) = range
+
+instance Ord (String, Maybe Range) where
+  (_, Just a) <= (_, Just b) = start a <= start b
+  _ <= _ = False