Reformulate Product/Coproduct with Isos

Author: garyb

src/Data/Lens/Iso/Coproduct.purs

@@ -0,0 +1,9 @@
+module Data.Lens.Iso.Coproduct where
+
+import Data.Functor.Coproduct (Coproduct(..), runCoproduct)
+import Data.Either (Either())
+
+import Data.Lens.Iso (Iso(), iso)
+
+_Coproduct :: forall f g h i a b. Iso (Coproduct f g a) (Coproduct h i b) (Either (f a) (g a)) (Either (h b) (i b))
+_Coproduct = iso runCoproduct Coproduct

src/Data/Lens/Iso/Product.purs

@@ -0,0 +1,9 @@
+module Data.Lens.Iso.Product where
+
+import Data.Functor.Product (Product(..), runProduct)
+import Data.Tuple (Tuple())
+
+import Data.Lens.Iso (Iso(), iso)
+
+_Product :: forall f g h i a b. Iso (Product f g a) (Product h i b) (Tuple (f a) (g a)) (Tuple (h b) (i b))
+_Product = iso runProduct Product

src/Data/Lens/Lens/Product.purs

@@ -1,14 +1,17 @@
 module Data.Lens.Lens.Product where
 
-import Data.Functor.Product (Product(..))
-import Data.Tuple (Tuple(..))
+import Prelude ((<<<))
 
-import Data.Lens.Lens (Lens(), lens)
+import Data.Functor.Product (Product())
 
--- | Lens for the first component of a `Product`.
+import Data.Lens.Iso.Product (_Product)
+import Data.Lens.Lens (Lens())
+import Data.Lens.Lens.Tuple as T
+
+-- | Lens for the `left` of a `Product`.
 _1 :: forall f g h a. Lens (Product f g a) (Product h g a) (f a) (h a)
-_1 = lens (\(Product (Tuple a _)) -> a) \(Product (Tuple _ c)) b -> Product (Tuple b c)
+_1 = _Product <<< T._1
 
--- | Lens for the second component of a `Product`.
+-- | Lens for the `right` of a `Product`.
 _2 :: forall f g h a. Lens (Product f g a) (Product f h a) (g a) (h a)
-_2 = lens (\(Product (Tuple _ a)) -> a) \(Product (Tuple c _)) b -> Product (Tuple c b)
+_2 = _Product <<< T._2

src/Data/Lens/Prism/Coproduct.purs

@@ -1,16 +1,17 @@
 module Data.Lens.Prism.Coproduct where
 
-import Prelude
+import Prelude ((<<<))
 
-import Data.Either (Either(..))
-import Data.Functor.Coproduct (Coproduct(), coproduct, left, right)
+import Data.Functor.Coproduct (Coproduct())
 
-import Data.Lens.Prism (Prism(), prism)
+import Data.Lens.Iso.Coproduct (_Coproduct)
+import Data.Lens.Prism (Prism())
+import Data.Lens.Prism.Either as E
 
 -- | Prism for the `left` of a `Coproduct`.
 _Left :: forall f g h a. Prism (Coproduct f g a) (Coproduct h g a) (f a) (h a)
-_Left = prism left $ coproduct Right (Left <<< right)
+_Left = _Coproduct <<< E._Left
 
 -- | Prism for the `right` of a `Coproduct`.
 _Right :: forall f g h a. Prism (Coproduct f g a) (Coproduct f h a) (g a) (h a)
-_Right = prism right $ coproduct (Left <<< left) Right
+_Right = _Coproduct <<< E._Right