From b134b72a44119fa85ec44bcdc5e7649f354ec4bd Mon Sep 17 00:00:00 2001
From: Gregor Kleen <gkleen@yggdrasil.li>
Date: Wed, 4 Nov 2015 18:46:43 +0100
Subject: mappend not imported

---
 ws2015/FFP/blaetter/03/FFP_U03_Funktoren.hs | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'ws2015')

diff --git a/ws2015/FFP/blaetter/03/FFP_U03_Funktoren.hs b/ws2015/FFP/blaetter/03/FFP_U03_Funktoren.hs
index 51ab9e5..935f9eb 100644
--- a/ws2015/FFP/blaetter/03/FFP_U03_Funktoren.hs
+++ b/ws2015/FFP/blaetter/03/FFP_U03_Funktoren.hs
@@ -184,3 +184,10 @@ instance Eq a => Eq (Options a) where
 
 instance Ord a => Ord (Tree a) where
   compare (Node x xs) (Node x' xs') = compare x x' `mappend` compare xs xs'
+    where
+      -- Siehe Data.Monoid
+      mappend LT _ = LT
+      mappend EQ EQ = EQ
+      mappend EQ LT = LT
+      mappend EQ GT = GT
+      mappend GT _ = GT
-- 
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