On Jul 27, 2010, at 3:02 AM, Brandon S Allbery KF8NH wrote: > As I understand it: > 1) carrying [contexts] around complicates Haskell98 (and now Haskell2010) > compatibility (also see below);
Like the availability of so many other features, this one could be controlled by a language pragma. > 2) GADTs do what you want, since they don't have backward compatibility > baggage. They are also more complex than is needed for the problem at hand. > > As to the current proposal, I think nobody's certain what would happen to > older programs if data were changed to carry contexts around --- someone > might be relying on the current behavior, and changing it might produce > runtime oddness instead of a compile-time error --- whereas making contexts > illegal will produce an easily-fixed error message in all relevant cases. Does anyone know why `data' contexts were broken in the first place? _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
