Re: [Haskell-cafe] AT solution: rebinding >>= for restricted monads

On Mon, Dec 18, 2006 at 06:52:41PM -0800, Iavor Diatchki wrote:

Hi David,

I don't think you need functional dependencies or associated type synonyms to get your example to work. In the past, I have used the abstraction that you are describing (I call it an "indexed monad" and it has a nice categorical definition).

The trouble is that your solution doesn't allow you to use do-notation with the IxMonad. And if you did allow yourself to use do-notation by rebinding (>>=), etc, then you wouldn't be able to use ordinary monads with do-notation in the same module. That's what makes things tricky, since an IxMonad is different-kinded from Monad, so you can't make a monad an instance of IxMonad. David