Merge pull request #24 from purescript/hoists

Add `hoist` functions

src/Data/Profunctor/Clown.purs

@@ -21,3 +21,6 @@ instance functorClown :: Functor (Clown f a) where
 
 instance profunctorClown :: Contravariant f => Profunctor (Clown f) where
   dimap f g (Clown a) = Clown (cmap f a)
+
+hoistClown :: forall f g a b. (f ~> g) -> Clown f a b -> Clown g a b
+hoistClown f (Clown a) = Clown (f a)

src/Data/Profunctor/Costar.purs

@@ -9,7 +9,7 @@ import Data.Distributive (class Distributive, distribute)
 import Data.Either (Either(..), either)
 import Data.Functor.Invariant (class Invariant, imapF)
 import Data.Newtype (class Newtype)
-import Data.Profunctor (class Profunctor)
+import Data.Profunctor (class Profunctor, lmap)
 import Data.Profunctor.Closed (class Closed)
 import Data.Profunctor.Cochoice (class Cochoice)
 import Data.Profunctor.Costrong (class Costrong)
@@ -73,3 +73,6 @@ instance cochoiceCostar :: Applicative f => Cochoice (Costar f) where
 
 instance closedCostar :: Functor f => Closed (Costar f) where
   closed (Costar f) = Costar \g x -> f (map (_ $ x) g)
+
+hoistCostar :: forall f g a b. (g ~> f) -> Costar f a b -> Costar g a b
+hoistCostar f (Costar g) = Costar (lmap f g)

src/Data/Profunctor/Joker.purs

@@ -20,3 +20,6 @@ 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)
+
+hoistJoker :: forall f g a b. (f ~> g) -> Joker f a b -> Joker g a b
+hoistJoker f (Joker a) = Joker (f a)

src/Data/Profunctor/Star.purs

@@ -77,3 +77,6 @@ instance choiceStar :: Applicative f => Choice (Star f) where
 
 instance closedStar :: Distributive f => Closed (Star f) where
   closed (Star f) = Star \g -> distribute (f <<< g)
+
+hoistStar :: forall f g a b. (f ~> g) -> Star f a b -> Star g a b
+hoistStar f (Star g) = Star (f <<< g)