[Haskell-cafe] Problems with nested Monads

wren ng thornton wren at freegeek.org
Sat Jul 11 00:26:32 EDT 2009

Job Vranish wrote:
> Yeah, I think the problem with my case is that while M is a specific monad
> (essentially StateT), N can be an arbitrary monad, which I think destroys my
> changes of making a valid joinInner/joinOuter/distribute.
> Maybe someday Haskell will infer valid joinInner/joinOuter for simple cases
> :D

Another alternative is to define a typeclass DistributesOverM, and 
provide instances for the particular monads, n, you care about. Just 
because you can't do it in general doesn't mean you can't do it :)

Live well,

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