[Haskell-cafe] problem with type equality constraints

Ganesh Sittampalam ganesh at earth.li
Mon Mar 17 17:41:43 EDT 2008

On Mon, 17 Mar 2008, Manuel M T Chakravarty wrote:

> Your are completely right.  Unfortunately, superclass equalities (ie, the Id 
> a ~ ida in the class declaration of Foo) aren't fully implemented yet.

OK, thanks. Is there any rough idea of when they will be?

> If I am not mistaken, superclass equalities, class defaults for 
> associated type families, and GADT data instances are the three major 
> features of type families/equality constraint saga that aren't fully 
> implemented yet.

Even with the rough edges, type families are really nice, thanks!



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