PVP proposal: don't require major version bump when adding non-orphan instances

[Yitzchak Gale]

Edward Kmett wrote:
> There may be some quibbling I'd take with the language though for the case
> where you have a package with classes and a package that has orphans for
> those classes for a package that was too burdensome to add as a dependency
> for the base package, both under the control of the same maintainer.
> (Mutatis mutandis for data types)
>
> An example would be vector-instances. As I control both it, and most of the
> packages it makes orphans for, I'm simply constraining myself from not
> releasing versions of those packages with conflicting instances unless I
> bump them out of bounds.
>
> I'd like to find a way to spell this out in clearer PVP'ese, but it is the
> way in which I'm most likely to be PVP non-compliant in the future.

Would it help to make an exception for "standards-track" libraries
like vector? In that case, orphan instances are expected to be
only temporarily orphan. Hopefully, they will all eventually make
their way to their permanent homes.

Thanks,
Yitz