Relaxin the PVP with regards to adding instances

Henning Thielemann schlepptop at
Thu Sep 6 11:10:05 CEST 2012

Am 06.09.2012 02:43, schrieb Michael Sloan:
> I agree that it's quite unfortunate that adding instances causes a
> major bump.  I think that instead it would make sense to only bump
> your major version whenever you add *orphan* instances.  This is
> because it is known to be dangerous to create orphan instances, and
> the errors are relatively transparent.  While I suppose it could break
> proper dependency resolution, a big reason for upper bounds is
> preventing a cascade of confusing errors.  With orphan instances the
> errors are very finite.
> In general here are a few different things that would help with the
> orphans problem:

There have been some ideas about explicit import of instances.

I also had some thoughts about how GHC can help managing orphan 
instances when they are necessary:

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