Merge pull request #30 from masaeedu/jokerchoice

Add instances for Joker

Author: garyb

src/Data/Profunctor/Joker.purs

@@ -2,8 +2,10 @@ module Data.Profunctor.Joker where
 
 import Prelude
 
+import Data.Either (Either(..))
+import Data.Newtype (class Newtype, un)
 import Data.Profunctor (class Profunctor)
-import Data.Newtype (class Newtype)
+import Data.Profunctor.Choice (class Choice)
 
 -- | Makes a trivial `Profunctor` for a covariant `Functor`.
 newtype Joker f a b = Joker (f b)
@@ -21,5 +23,20 @@ instance functorJoker :: Functor f => Functor (Joker f a) where
 instance profunctorJoker :: Functor f => Profunctor (Joker f) where
   dimap f g (Joker a) = Joker (map g a)
 
+instance clownJoker :: Functor f => Choice (Joker f) where
+  left  (Joker f) = Joker $ map Left f
+  right (Joker f) = Joker $ map Right f
+
+instance applyJoker :: Apply f => Apply (Joker f a) where
+  apply (Joker f) (Joker g) = Joker $ apply f g
+
+instance applicativeJoker :: Applicative f => Applicative (Joker f a) where
+  pure = Joker <<< pure
+
+instance bindJoker :: Bind f => Bind (Joker f a) where
+  bind (Joker ma) amb = Joker $ ma >>= (amb >>> un Joker)
+
+instance monadJoker :: Monad m => Monad (Joker m a)
+
 hoistJoker :: forall f g a b. (f ~> g) -> Joker f a b -> Joker g a b
 hoistJoker f (Joker a) = Joker (f a)