Hi Matthew > I like the proposal. I also support the covariance. > > One question though. > The RFC mentions possible future use of "nothing" as a bottom type for > parameters in generics. This makes a lot of sense to me. Even without > generics, it could be used for parameters in abstract methods. > > So why not already introduce "nothing" as the universal bottom type, and > use it instead of "noreturn"? > Can "noreturn" do anything that "nothing" can't?
I'm also a little confused by this statement. The exact wording from the RFC is: > Arguments for never: ... It's a full-fledged type, rather than a keyword used > in a specific situation. A far-in-the-future generics proposal could use > never as a placeholder inside contravariant generic types. >From what I understand, in Hack noreturn and never are both full-fledged types. Nothing is a bottom type while noreturn is not. Since in your proposal noreturn would also be a bottom type there's no reason why it couldn't be used in covariant or contravariant generic parameters. Please correct me if I'm missing something. Ilija -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: https://www.php.net/unsub.php
