Closed, Cochoice and Costrong.

In preparation of a proper `re` and `Grate`s in
profunctor-lenses.

Author: zrho

src/Data/Profunctor/Closed.purs

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+module Data.Profunctor.Closed where
+
+import Prelude
+
+import Data.Profunctor
+
+-- | The `Closed` class extends the `Profunctor` class to work with functions.
+class (Profunctor p) <= Closed p where
+  closed :: forall a b x. p a b -> p (x -> a) (x -> b)
+
+instance Closed Function where
+  closed = (<<<)

src/Data/Profunctor/Cochoice.purs

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+module Data.Profunctor.Cochoice where
+
+import Prelude
+
+import Data.Either (Either ())
+import Data.Profunctor
+
+-- | The `Cochoice` class provides the dual operations of the `Choice` class.
+class (Profunctor p) <= Cochoice p where
+  unleft :: forall a b c. p (Either a c) (Either b c) -> p a b
+  unright :: forall a b c. p (Either a b) (Either a c) -> p b c

src/Data/Profunctor/Costrong.purs

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+module Data.Profunctor.Cochoice where
+
+import Prelude
+
+import Data.Either (Tuple ())
+import Data.Profunctor
+
+-- | The `Costrong` class provides the dual operations of the `Strong` class.
+class (Profunctor p) <= Costrong p where
+  unfirst :: forall a b c. p (Tuple a c) (Tuple b c) -> p a b
+  unsecond :: forall a b c. p (Tuple a b) (Tuple a c) -> p b c