git.iko.soy/patch
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CPP Maybe's superclasses
f60f1a0John Ericson
src/Data/Monoid/DecidablyEmpty.hs+7−1
compare with develop
unifiedsplit
@@ -46,7 +46,13 @@ instance DecidablyEmpty All
46-- instance DecidablyEmpty Event
46-- instance DecidablyEmpty Event
47instance DecidablyEmpty [a] where
47instance DecidablyEmpty [a] where
48 isEmpty = null
48 isEmpty = null
49+instance
50+#if MIN_VERSION_base(4,10,0)
51+ Semigroup a
52+#else
53+ Monoid a
54+#endif
49−instance Semigroup a => DecidablyEmpty (Maybe a) where
55+ => DecidablyEmpty (Maybe a) where
50 isEmpty = isNothing
56 isEmpty = isNothing
51deriving instance (Num a, DecidablyEmpty a) => DecidablyEmpty (Product a)
57deriving instance (Num a, DecidablyEmpty a) => DecidablyEmpty (Product a)
52deriving instance (DecidablyEmpty a, Num a) => DecidablyEmpty (Sum a)
58deriving instance (DecidablyEmpty a, Num a) => DecidablyEmpty (Sum a)