GHC2024 – community input

[jaror]

Yes, I just think it is not a good idea to add even more ways to trigger that unsafety to the default language. As I said:

@jaror

I think that inclusion of an extension in GHC20XX should also mean that the extension is hard to abuse by those who are unfamiliar with the extension and their possible harmful consequences. Or conversely, if an extension is included then everyone should be encouraged to check it out and try to use it in their programs.

I wouldn’t want to encourage everyone to start using coerce everywhere and so I don’t want to encourage everyone to use DerivingVia everywhere either.

But I think there is a relatively easy fix: declare once and for all that Data.Coerce is safe (and perhaps check Hackage for unsafe existing code). If we can collectively make that decision (and we improve the error messages) then I think it is fine to add DerivingVia.