Hi. >> No, I don't think it should. I consider it a tiny addition to >> TypeFamilies that is not worth having its separate pragma. Injective >> TFs are fully backwards compatible, so no existing code >> will be broken. >> > That being said, it does claim new syntax and consequently would be > rather difficult to back out if we realize that this implementation > isn't the right direction. I don't have a strong opinion here, just > playing devil's advocate.
I think it should be a new language extension. Forward compatibility on its own is not a sufficient argument. Aren't e.g. GADTs forward compatible? Or functional dependencies? Or flexible instances? Yet all of these also have separate language extensions. If I actually want to write backward-compatible type family code using GHC-8.0, I'd prefer to be able to enable TypeFamilies yet not InjectiveTypeFamilies, and have GHC check that I am in the common subset. Also, I think it would be nice to be able to track how many packages will make use of TypeFamilies and InjectiveTypeFamilies separately from each other. Cheers, Andres _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs
