From b5f74091bf655513e539c4048d789da89dd27ca7 Mon Sep 17 00:00:00 2001 From: Ross Paterson Date: Fri, 2 Feb 2007 19:08:47 +0000 Subject: [PATCH] add derived instances for Dual monoid --- Data/Monoid.hs | 1 + 1 file changed, 1 insertion(+) diff --git a/Data/Monoid.hs b/Data/Monoid.hs index 8a30b73..c51c4ca 100644 --- a/Data/Monoid.hs +++ b/Data/Monoid.hs @@ -97,6 +97,7 @@ instance Monoid Ordering where -- | The dual of a monoid, obtained by swapping the arguments of 'mappend'. newtype Dual a = Dual { getDual :: a } + deriving (Eq, Ord, Read, Show, Bounded) instance Monoid a => Monoid (Dual a) where mempty = Dual mempty -- 1.7.10.4