Re[4]: All Monads are Functors

Hello Taral, Monday, August 14, 2006, 3:34:29 PM, you wrote:

On 8/14/06, Jon Fairbairn wrote:

...

of course, there's no reason to do that, but what I'm proposing is that we allow default instance declarations in class declarations in much the same way as default methods:

I just realized that default superclass methods have a small problem:

module A contains instance Monad [] module B contains instance Functor [] module C imports A and B.

Do we complain about a duplicate instance declarations?

yes. after all, this is just syntax sugar of giving both declarations: instance Monad [] where fmap = map return = (:[]) is equivalent to instance Functor [] where fmap = map instance Monad [] where return = (:[]) -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com