Should the PVP be changed with regards to instances?

[Henning Thielemann]

On Tue, 20 Dec 2011, Erik Hesselink wrote:

> I'd ask you to follow the PVP here. Problems with duplicate instances
> are often tricky to resolve, and not something you want to encounter
> when you're developing (not upgrading dependencies). I've often added
> orphan instances for types from other packages. Yes, I should (and
> often do) send these upstream, but I still add them locally. I have to
> have the instance now, to continue my work, and there's no telling
> when a new version of the original package will be released. The other
> option is forking the package, which means I also don't get bugfix
> updates anymore.

A better option is using a newtype and add the missing instances there.