On Mon, Dec 21, 2009 at 4:10 AM, Antoine Latter
Folks,
Would there be support for splitting off the MonadIO class from the mtl, and simple having Control.Monad.Trans re-export it? My proposed packaging of the functionality is here: http://community.haskell.org/~aslatter/code/monad-iohttp://community.haskell.org/%7Easlatter/code/monad-io
Here's my problem which prompted this:
I'm converting a library of mine over to the failure[1] package for returning errors, and the type on a lot of my functions is as follows:
(MonadFailure MyFailureType m, MonadIO m) => Alpha -> Beta -> m Gamma
The MonadFailure constraint is defined separate from its many instances, which would give the consumers of my library the choice between using the mtl or the transformers[2] library.
Except that I also need a MonadIO constraint, for which I must pick from which package I choose it.
Antoine
[1] http://hackage.haskell.org/package/failure _______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries
+1, this is a great idea. I've had to purposely remove useful functions from safe-failure package due to this issue as well. I think we all agree that the best choice is to merge mtl and transformers, but since that discussion seems to have come to a stand-still, splitting off MonadIO and MonadTrans seems like a good second best. Of course, I won't complain if someone just fixes the mtl/transformers mess itself ;). Michael