Can we offer ~ without GADTs or type families?

[Eric Crockett]

As a user who frequently uses ~, but doesn't need the rest of GADTs or
TypeFamilies, I'd really like to see a TypeEqualities extension!

Eric

On Fri, Aug 5, 2016 at 3:27 PM, Adam Gundry <adam at well-typed.com> wrote:

> On 05/08/16 19:08, David Feuer wrote:
> > It seems to me that equality constraints could potentially be supported
> > by an implementation with neither GADTs nor type families. Type families
> > don't really seem to have much to do with it, and GADTs are strictly
> > heavier (GADTs ~= ExistentialQuantification + TypeEquality).
> >
> > Could we get a separate LANGUAGE pragma just for equality constraints?
>
> I suggested this in #10431 [1], where there is some discussion of the
> implications. I still think it is a good idea, and I don't think the
> implementation would be very difficult.
>
> All the best,
>
> Adam
>
> [1] https://ghc.haskell.org/trac/ghc/ticket/10431
>
>
> --
> Adam Gundry, Haskell Consultant
> Well-Typed LLP, http://www.well-typed.com/
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