[Haskell-cafe] A question about functional dependencies and existential quantification

[Jean-Marie Gaillourdet]

Hi,

thanks for your quick answer. Do you have any predictions when System
F_c in GHC will be available for usage?

Regards,
  Jean-Marie

Simon Peyton-Jones wrote:
> What you want to do is perfectly reasonable -- but it cannot be translated into System F and that's why GHC rejects it.
> 
> GHC now has a richer intermediate language that *can* handle this; see our paper http://research.microsoft.com/~simonpj/papers/ext-f.
> 
> Manuel and Martin and I are now working on the *source*-language aspects, incl type inference.  When we are done, we'll be able to compile your program, or at least one very like it.
> 
> So, stay tuned.  Meanwhile thank you for the example.