Add Functor, Foldable, Traversable too

Author: garyb

src/Data/Lens/Internal/Tagged.purs

@@ -5,12 +5,14 @@ import Prelude
 
 import Data.Either (Either(..))
 import Data.Eq (class Eq1)
+import Data.Foldable (class Foldable)
 import Data.Newtype (class Newtype)
 import Data.Ord (class Ord1)
 import Data.Profunctor (class Profunctor)
 import Data.Profunctor.Choice (class Choice)
 import Data.Profunctor.Closed (class Closed)
 import Data.Profunctor.Costrong (class Costrong)
+import Data.Traversable (class Traversable)
 import Data.Tuple (Tuple(..))
 
 newtype Tagged a b = Tagged b
@@ -23,6 +25,8 @@ instance eq1Tagged :: Eq1 (Tagged a) where eq1 = eq
 derive instance ordTagged :: Ord b => Ord (Tagged a b)
 instance ord1Tagged :: Ord1 (Tagged a) where compare1 = compare
 
+derive instance functorTagged :: Functor (Tagged a)
+
 instance taggedProfunctor :: Profunctor Tagged where
   dimap _ g (Tagged x) = Tagged (g x)
 
@@ -36,3 +40,12 @@ instance taggedCostrong :: Costrong Tagged where
 
 instance taggedClosed :: Closed Tagged where
   closed (Tagged b) = Tagged (const b)
+
+instance foldableTagged :: Foldable (Tagged a) where
+  foldMap f (Tagged a) = f a
+  foldr f b (Tagged a) = f a b
+  foldl f b (Tagged a) = f b a
+
+instance traversableTagged :: Traversable (Tagged a) where
+  sequence (Tagged a) = map Tagged a
+  traverse f (Tagged a) = map Tagged (f a)