Re: Should the PVP be changed with regards to instances?

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.