alt Hacker NewsEditions allow making breaking changes to Rust without splitting the ecosystem - no hassle caused to existing code unless it opts into the new edition and its breaking changes. There's currently editions 2015, 2018, 2021, and 2024. When a new edition is introduced, it can make breaking changes such as introducing new keywords, but every previous edition remains supported forever by newer compiler versions.
The key part is that editions are configured per-library - libraries A and B might use editions 2015 and 2021, and your application could use edition 2018 and depend on those libraries, and it works.
If you wrote a library with the original 2015 edition, and never upgraded it to deal with new `async` and `await` keywords added in the 2018 edition, that's totally fine. Newer compilers will continue to compile it in its configured edition=2015 mode, where the new keywords don't exist (so your local variable named `async` still compiles), and new code written against newer editions may still use this 2015 edition library with no issue.
Editions are different from Go version directives because you use them to say "my library needs features added in this Go version", but they don't enable Go to make breaking changes to the language.
Editions can't do every kind of breaking change however - they mostly work for syntax level changes, and don't work for things like tearing out regrettable parts of the standard library.
> The key part is that editions are configured per-library - libraries A and B might use editions 2015 and 2021
In what way is that key? It still reads as being the same as the Go version directive. Obviously there are some differences in the implementation. For example, Go puts it in go.mod, while Rust puts it in Cargo.toml, but at a conceptual level I fail to see any fundamental difference. As you describe it, and how the documentation describes it, they attempt to accomplish the same thing for the same reason.
But, as phire puts it, they are "very different". But I don't see how. The carrying on of the tradition of the Rust community being horrible at communication carries on, I'm afraid. As before, you are going to have to speak to those who aren't deep in the depths of programming languages. Dumb it down for the reader who uses PHP and who has never touched Go or Rust in their life.
> they don't enable Go to make breaking changes to the language.
What, exactly, do you mean? The change to loop variable semantics comes to mind that was clearly a breaking change to the language, but gracefully handled with the version directive. What purpose are you under the impression the directive serves if not for dealing with breaking changes?