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Add some instances for NonEmpty

This commit is contained in:
Michael Walker 2015-07-21 16:09:11 +01:00
parent c786a30448
commit 112a7cd138

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@ -1,7 +1,10 @@
-- | Extra list functions and list-like types.
module Data.List.Extra where
import Control.Applicative ((<$>), (<*>))
import Control.DeepSeq (NFData(..))
import Data.Foldable (Foldable(..))
import Data.Traversable (Traversable(..), fmapDefault, foldMapDefault)
-- * Regular lists
@ -21,7 +24,13 @@ moreThan (_:xs) n = moreThan xs (n-1)
data NonEmpty a = a :| [a] deriving (Eq, Ord, Read, Show)
instance Functor NonEmpty where
fmap f (a :| as) = f a :| map f as
fmap = fmapDefault
instance Foldable NonEmpty where
foldMap = foldMapDefault
instance Traversable NonEmpty where
traverse f (a:|as) = (:|) <$> f a <*> traverse f as
instance NFData a => NFData (NonEmpty a) where
rnf (x:|xs) = rnf (x, xs)