Remove 'arr', fix #5

Author: paf31

docs/Module.md

@@ -6,7 +6,6 @@
 
 ``` purescript
 class (Category a, Strong a) <= Arrow a where
-  arr :: forall b c. (b -> c) -> a b c
 ```
 
 

src/Control/Arrow.purs

@@ -3,11 +3,9 @@ module Control.Arrow where
 import Data.Profunctor.Strong
 import Data.Tuple (Tuple(..), swap)
 
-class (Category a, Strong a) <= Arrow a where
-  arr :: forall b c. (b -> c) -> a b c
+class (Category a, Strong a) <= Arrow a
 
-instance arrowFunction :: Arrow (->) where
-  arr f = f
+instance arrowFunction :: Arrow (->)
 
 class ArrowZero a where
   azero :: forall b c. a b c

src/Control/Arrow/Cokleisli.purs

@@ -26,5 +26,4 @@ instance strongCokleisli :: (Comonad m) => Strong (Cokleisli m) where
   first (Cokleisli f) = Cokleisli \w -> Tuple (f (fst <$> w)) (snd (extract w)) 
   second (Cokleisli f) = Cokleisli \w -> Tuple (fst (extract w)) (f (snd <$> w))
 
-instance arrowCokleisli :: (Comonad m) => Arrow (Cokleisli m) where
-  arr f = Cokleisli (f <<< extract)
+instance arrowCokleisli :: (Comonad m) => Arrow (Cokleisli m)

src/Control/Arrow/Kleisli.purs

@@ -23,5 +23,4 @@ instance strongKleisli :: (Monad m) => Strong (Kleisli m) where
   first (Kleisli f) = Kleisli \(Tuple a c) -> f a >>= \b -> return (Tuple b c)
   second (Kleisli f) = Kleisli \(Tuple c a) -> f a >>= \b -> return (Tuple c b)
 
-instance arrowKleisli :: (Monad m) => Arrow (Kleisli m) where
-  arr f = Kleisli (return <<< f)
+instance arrowKleisli :: (Monad m) => Arrow (Kleisli m)