Multiple instance pragmas

[Brandon Allbery]

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> 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
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-- 
brandon s allbery kf8nh
allbery.b at gmail.com
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