Henrik Nilsson
Dear all,
John Mecham wrote:
Yeah, I have been coming to the same conclusion myself. it pains me a lot. (monad transformers! I need thee!) but its not like fundeps will go away, they will just still be experimental so it isn't the end of the world.
But isn't the whole point of Haskell' to standardise those features that are agreed to be necessary for writing real-world applications and libraries in a reasonable way?
My concern is not that I fear not being able to compile my programs after Haskell' is done. I'm worried about too much code not being Haskell' compliant in the end, and, worse, too many people deciding that they still have to rely on extensions beyond Haskell' for writing "real" applications and libraries.
I am very concerned about this as well. In most of my production code, I avoid extensions, but MPTC and functional dependencies are two that I have not been able to avoid. Any time I use the class system, I use MPTC, anytime I use MPTC, I use fundeps. The trouble with "blessing" fundeps is that they might not pan out in the end, and it would be a shame to add them to Haskell' and then remove them again for Haskell'' (if there were such a thing) in favor of associated types, for instance. How do we solve this dilemma? Some proposals that have come up: - Simon has proposed that we examine a limited version of functional dependencies. - Another option, though a scary one at this point, is to look closely at associated types. - Another option is to punt; we declare them as an extension and figure out a way to "bless" extensions (beyond Cabal, I guess). - Any others? Can someone put together a wiki page these choices with trade-offs? Ravi, Manuel? peace, isaac