From a9ccc950c60d8d3bc48b80fbb6af8a6118d3bff0 Mon Sep 17 00:00:00 2001
From: Iustin Pop <iustin@google.com>
Date: Sun, 19 Aug 2012 01:48:54 +0200
Subject: [PATCH] Add a Functor instance for our Result type

This will allow us to use the simpler applicative form (<$>, <*>)
instead of monadic liftM, liftM2, etc.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Agata Murawska <agatamurawska@google.com>
---
 htools/Ganeti/BasicTypes.hs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/htools/Ganeti/BasicTypes.hs b/htools/Ganeti/BasicTypes.hs
index 55bab2858..d68387e9e 100644
--- a/htools/Ganeti/BasicTypes.hs
+++ b/htools/Ganeti/BasicTypes.hs
@@ -56,6 +56,10 @@ instance Monad Result where
   return = Ok
   fail = Bad
 
+instance Functor Result where
+  fmap _ (Bad msg) = Bad msg
+  fmap fn (Ok val) = Ok (fn val)
+
 instance MonadPlus Result where
   mzero = Bad "zero Result when used as MonadPlus"
   -- for mplus, when we 'add' two Bad values, we concatenate their
-- 
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