Multiple instance pragmas

[Richard Eisenberg]

I agree -- I think INCOHERENT essentially subsumes the others. Do you have a counter-example?

Richard

> On Nov 25, 2019, at 4:28 PM, Brandon Allbery <allbery.b at gmail.com> wrote:
> 
> TBH I'd have expected INCOHERENT to cover OVERLAPPABLE, i.e. all bets are off and you've allowed anything including overlaps.
> 
> On Mon, Nov 25, 2019 at 11:26 AM Domínguez, Facundo <facundo.dominguez at tweag.io <mailto:facundo.dominguez at tweag.io>> wrote:
> Dear devs,
> 
> I have a program [1] which depends on the ability to specify some instances to be both overlappable and incoherent.
> 
> GHC so far, allows only one of the OVERLAPPABLE or INCOHERENT pragmas to be specified per instance. One can still have an overlappable and incoherent instance by using -XIncoherenInstances, but this extension is deprecated.
> 
> Is there any chance that a patch is accepted to allow multiple instance pragmas? And if not, what would the reason for this constraint?
> 
> Thanks,
> Facundo
> 
> [1] https://gist.github.com/facundominguez/2c0292bf6a721b450c46486ff3b71f24 <https://gist.github.com/facundominguez/2c0292bf6a721b450c46486ff3b71f24>_______________________________________________
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> 
> -- 
> brandon s allbery kf8nh
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