[commit: base] master: Use sharing in the Alternative instance of Maybe (1d97ad1)

[Ian Lynagh]

Repository : ssh://darcs.haskell.org//srv/darcs/packages/base

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/1d97ad10283d23b6dfb698a38ae57c29accd6ada

>---------------------------------------------------------------

commit 1d97ad10283d23b6dfb698a38ae57c29accd6ada
Author: Bas van Dijk <v.dijk.bas at gmail.com>
Date:   Wed Dec 14 12:24:38 2011 +0100

    Use sharing in the Alternative instance of Maybe

>---------------------------------------------------------------

 Control/Applicative.hs |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/Control/Applicative.hs b/Control/Applicative.hs
index bf58bea..3a9db61 100644
--- a/Control/Applicative.hs
+++ b/Control/Applicative.hs
@@ -156,8 +156,8 @@ instance Applicative Maybe where
 
 instance Alternative Maybe where
     empty = Nothing
-    Nothing <|> p = p
-    Just x <|> _ = Just x
+    Nothing <|> r = r
+    l       <|> _ = l
 
 instance Applicative [] where
     pure = return