Re: [Haskell-cafe] Why the reluctance to introduce the Functor requirement on Monad?

25 Jul 2011


      On Mon, 2011-07-25 at 00:11 -0400, August Sodora wrote:
...
Out of (perhaps naive) curiosity, what difficulties does allowing such
overriding introduce? Wouldn't the module system prevent the ambiguity
of which implementation to use?
August Sodora
augsod@gmail.com
(201) 280-8138
class A a where
  a :: a

class A a => B b where
  b :: b
  
  a = b

class A a => C c where
  c :: c

  a = c

data BC = B | C deriving Show

instance B BC where
  b = B

instance C BC where
  c = C

show (a :: BC) == ???

Regards

Re: [Haskell-cafe] Why the reluctance to introduce the Functor requirement on Monad?

Maciej Marcin Piechotka