From c4702a7f6ef03a852afec98167edc8996e08c5a3 Mon Sep 17 00:00:00 2001
From: Neil Brown <neil@twistedsquare.com>
Date: Fri, 30 May 2008 17:14:28 +0000
Subject: [PATCH] Added a new helper function, eitherToMaybe in Utils

---
 common/Utils.hs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/common/Utils.hs b/common/Utils.hs
index 2d93709..8046a35 100644
--- a/common/Utils.hs
+++ b/common/Utils.hs
@@ -312,5 +312,9 @@ mapMapWithKeyM f m = liftM Map.fromAscList $ mapM f' $ Map.toAscList m
     f' (x,y) = do y' <- f x y
                   return (x, y')
 
+-- | Transforms an Either into a Maybe.  If it's a Left value, it is transformed
+-- into Nothing.  If it is a Right value, it is transformed into Just.
+eitherToMaybe :: Either a b -> Maybe b
+eitherToMaybe = either (const Nothing) Just