Re: [ghc-steering-committee] Proposal: Type Fixity (#65), Consensus: accept, own language extension?

On Oct 18, 2017, at 4:49 PM, Joachim Breitner wrote:

The way out there might be to try our best, and if we get it wrong and mark an extension as stable too early, we’ll just have to add a new pragma for the improved ones… so that seems like a good compromise.

Yes, this is exactly what I was thinking. For example, TypeFamilies might have been marked as stable before closed type families came about... but then we would just have -XClosedTypeFamilies -- not so horrible.

The other failure mode would be that we will have _too strict_ requirements for marking extensions as stable, so that production code will inevitably have to use non-stable extensions, and not much is gained.

This, too, is exactly what I was thinking. Industrial users and book authors have the most to gain from an extension being marked as stable. I would expect that proposals would come from these groups marking extensions as stable, and then we could have a debate. Richard