Krasimir Angelov wrote:
[...] Well! I expect future discussion in the libraries@haskell.org. I propose to extract the type classes in the new module (maybe Control.Monad.Attributes) and after that to add attribute types along with their instances to modules which defines corresponding monads. [...]
Just some last remarks before we *really* move this thread to the libraries list: * Is there a way to fit your proposal into the existing Control.Monad.* hierarchy by splitting MonadState into a read and a write part? * Can we merge this somehow with Hughes' RefMonad? (http://www.math.chalmers.se/~rjmh/Globals.ps) * The need for the functional dependencies is not 100% clear to me. * Do we really need MPTC or can we get by with constructor classes somehow? This is a question I'm asking me from time to time in different contexts, too. Due to a lack of time, I haven't spent much time thinking about these issues for myself, but I think they should be clarified. Cheers, S.