[spdegabrielle]

This is addressed in the blog post linked from the release announcement: https://blog.racket-lang.org/2025/11/parallel-threads.html

[ModernMech]

That post is even more worrisome!

> To address larger problems with the implementation and to improve performance, we started in 2017 rebuilding Racket on top of Chez Scheme. Rebuilding took some time, and we only gradually deprecated the old “BC” implementation in favor of the new “CS” implementation, but the transition is now complete. Racket BC is still maintained, but as of August 2025, we distribute only Racket CS builds

So they're billing Racket as "Mature Practical Extensible Robust and Polished". Of those I will give them "Extensible" and "Robust". You can't say you're mature and polished and practical if you've just rewritten the entire thing and deprecated the legacy codebase to support new features that have been in other languages since forever.

Maybe they were talking about Racket 8.0 and didn't change the website yet?

[nesarkvechnep]

How rewriting something internally makes Racket not mature? Sounds like refactoring to me and with an extensive test suite there's nothing to be hysterical about.

[nothrabannosir]

They might be making a distinction between the language and the current implementation. In fact I would call going through multiple different fundamental implementations without changing the semantics, an argument in favor of the maturity of the language.