Add map function

Author: colehaus

src/Data/NonEmpty.purs

@@ -71,6 +71,11 @@ head (x :| _) = x
 tail :: forall f a. NonEmpty f a -> f a
 tail (_ :| xs) = xs
 
+-- | Useful for functorish non-functors like `Set`.
+-- > NonEmpty.map Set.map (_ + 1)
+map :: forall a b f. ((a -> b) -> f a -> f b) -> (a -> b) -> NonEmpty f a -> NonEmpty f b
+map mapper f (a :| as) = (f a :| mapper f as)
+
 instance showNonEmpty :: (Show a, Show (f a)) => Show (NonEmpty f a) where
   show (a :| fa) = "(NonEmpty " <> show a <> " " <> show fa <> ")"