Re: [Haskell-cafe] Constraints on data-types, mis-feature?

On Tuesday 10 July 2007, Jim Apple wrote:

On 7/9/07, Jonathan Cast wrote:

...

GADTs don't change anything (at least, not the last time I checked).

GHC (in HEAD, at least) eliminates this wart for any datatype declared with GADT syntax.

http://www.haskell.org/ghc/dist/current/docs/users_guide/data-type-extensio ns.html#gadt-style

"Any data type that can be declared in standard Haskell-98 syntax can also be declared using GADT-style syntax. The choice is largely stylistic, but GADT-style declarations differ in one important respect: they treat class constraints on the data constructors differently. Specifically, if the constructor is given a type-class context, that context is made available by pattern matching."

I'll definitely check this out; I've been quite annoyed by this restriction in the past. Jonathan Cast http://sourceforge.net/projects/fid-core http://sourceforge.net/projects/fid-emacs