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

On Sun, Dec 17, 2006 at 01:35:49PM -0500, Chung-chieh Shan wrote:

David Roundy wrote:

...

class WitnessMonad wm where (>>=) :: wm w w' a -> (a -> wm w' w'' b) -> wm w w'' b (>>) :: wm w w' a -> wm w' w'' b -> wm w w'' b return :: a -> wm w w' a fail :: String -> wm w w' a

I suspect that you want "w" and "w'" to be the same type in the types of "return" and "fail".

You're right. That was silly of me.

Previous work:

Atkey, Robert. 2006. Parameterised notions of computation. In MSFP 2006: Workshop on mathematically structured functional programming, ed. Conor McBride and Tarmo Uustalu. Electronic Workshops in Computing, British Computer Society. http://homepages.inf.ed.ac.uk/ratkey/param-notions.pdf

http://haskell.org/pipermail/haskell-cafe/2004-July/006448.html

Hmmm. Those look interesting, but don't seem to address the question of trying this in actual Haskell. I don't see any reason why this overloading wouldn't work, except for the inconvenience of having to lift and unlift everything that's not in a fun monad. Do you? Mightn't there be a way around that issue? -- David Roundy Department of Physics Oregon State University