[Haskell-cafe] Re: Improving MTL instances (was: Overlapping/Incoherent instances)
ryani.spam: On Mon, Oct 13, 2008 at 2:04 AM, J. Garrett Morris [EMAIL PROTECTED] wrote: Indeed - MTL seems to have been rewritten at some point in the past to prefer exhaustive enumeration to overlap. Indeed, and I actually think this is a weakness of the current implementation. Anyone who comes up with a new transformer that provides different functionality than what is there needs to explicitly provide all the relevant instances, instead of letting MonadTrans do its thing. I just want to make one small point here encouraging people to try out new 'mtl' libraries. There are lots of *new* monad libraries, The new improved mtl: * monadLib http://hackage.haskell.org/cgi-bin/hackage-scripts/package/monadLib As well as, * mmtl http://hackage.haskell.org/cgi-bin/hackage-scripts/package/mmtl * mtl-tf http://hackage.haskell.org/cgi-bin/hackage-scripts/package/mtl-tf and the huge, * category-extras http://hackage.haskell.org/cgi-bin/hackage-scripts/package/category-extras 'mtl' isn't magic in any way. it isn't distributed with ghc, so we can let the (library) free market pick a winner. Now, if the monadLib guys would advertise their work a bit more effectively... -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Improving MTL instances (was: Overlapping/Incoherent instances)
On Mon, Oct 13, 2008 at 12:29 AM, Ryan Ingram [EMAIL PROTECTED] wrote: Of course, the point of this message isn't just to complain. The overlap implementation was abhorrent and it *is* better now than it was before. I'm curious what you find abhorrent about the overlap implementation that was there before - in particular, it seems like it was designed to handle both the combinatorial explosion and the corner cases you mentioned. Did you find writing the MonadTrans instances unpleasant? Was it the presence of overlapping instances at all? On Mon, Oct 13, 2008 at 12:35 AM, Don Stewart [EMAIL PROTECTED] wrote: I just want to make one small point here encouraging people to try out new 'mtl' libraries. There are lots of *new* monad libraries, Without knowing better myself: do any of these libraries address the issue Ryan's brought up? I know that monadLib takes the same approach the MTL does to this, and so is likely to have the same difficulties. /g -- I am in here ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Improving MTL instances (was: Overlapping/Incoherent instances)
Hello, The currently released version of monadLib does not use overlapping instances, indeed. However, in the monadLib repo (http://github.com/yav/monadlib) there is a file called MonadLib4.hs which contains a version of the library that is implemented with overlapping instances, so you can play around with it. I'd be interested to get feedback on this version of moandLib. -Iavor On Mon, Oct 13, 2008 at 12:44 AM, J. Garrett Morris [EMAIL PROTECTED] wrote: On Mon, Oct 13, 2008 at 12:29 AM, Ryan Ingram [EMAIL PROTECTED] wrote: Of course, the point of this message isn't just to complain. The overlap implementation was abhorrent and it *is* better now than it was before. I'm curious what you find abhorrent about the overlap implementation that was there before - in particular, it seems like it was designed to handle both the combinatorial explosion and the corner cases you mentioned. Did you find writing the MonadTrans instances unpleasant? Was it the presence of overlapping instances at all? On Mon, Oct 13, 2008 at 12:35 AM, Don Stewart [EMAIL PROTECTED] wrote: I just want to make one small point here encouraging people to try out new 'mtl' libraries. There are lots of *new* monad libraries, Without knowing better myself: do any of these libraries address the issue Ryan's brought up? I know that monadLib takes the same approach the MTL does to this, and so is likely to have the same difficulties. /g -- I am in here ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
