@@ -3,7 +3,12 @@
3-- TODO upstream somwhere else?
3-- TODO upstream somwhere else?
4module Data.Monoid.DecidablyEmpty where
4module Data.Monoid.DecidablyEmpty where
6class Monoid a => DecidablyEmpty a where
8class Monoid a => DecidablyEmpty a where
7 isEmpty :: a -> Bool
9 isEmpty :: a -> Bool
8 default isEmpty :: Eq a => a -> Bool
10 default isEmpty :: Eq a => a -> Bool
9 isEmpty = (==) mempty
11 isEmpty = (==) mempty
13+instance DecidablyEmpty (Proxy a) where
14+ isEmpty ~Proxy = True