> 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?
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.
Maybe I just have a different working definition of these words. To me "mature" means "fully developed" and "polished" means "achieved a high level of refinement". To me, rewriting it all to introduce a major feature that fills in a longstanding hole in the language doesn't say "mature and polished". Because often times many bugs are introduced into a codebase on a major rewrite despite extensive test suites, especially at the interfaces between features. Typically people might prefer a mature codebase to one that's just been rewritten precisely because it hasn't been vetted over years. "mature rewrite" sounds like an oxymoron to me, and I guess no one else agrees but I find it strange. That is all.
I think they don't always communicate well with industry practitioners, and your reactions are great evidence of that.
Racket is lead by professors, and (as is sometimes the case in systems research) some of them are very highly skilled software developers, well above HN average. But they have not been working in industry, and some have never worked in industry, so they don't always know what notes to hit, and they don't always know current subtleties of practice.
My best example of this is when someone kept saying the platform was "batteries included". My reaction was, my god, no, please don't say that: the first time the wrong person sees that, invests time with that expectation, and finds all the ways that is absolutely not true by industry convention, they will rip the ecosystem a new one.
Set expectations properly, and you attract the right people, who will love it, and they will also disproportionately be great programmers.
That said, the software engineering quality situation is much better than the impression you seem to have. They've done a very solid job of rehosting Racket internals, and of generally maintaining backward-compatibility over the years. Much better than Python, for example. (Also, Racket docs are usually much better than most ecosystems I have used in recent years.)
Fears about refactoring introducing bugs are fine and valid - but after eight years, haven't really happened. Seems the extensive test suite did its job.
This isn't a case of Python 2 v 3. Packages weren't broken en masse. The API remained stable.
If anything, the rewrite has proved that it is mature. Because they could perform a refactor without breaking everyone's everyday.
I agree. I remember very few bugs caused by the rewrite, but I don't remember recent ones.
For example, I found a bug running the tests of the r7rs package, it was simplified to a bug in "plain" Racket and later fixed, 3 days after the initial report. It was in June 2019 https://github.com/racket/racket/issues/2675 Note that at that time, the default version of Racket was he old one (before the rewrite).
Nobody would consider Chrome or Firefox to be immature or lacking polish because they have replaced entire compilers several times over the past few years? I don't have an exact count, but they probably do this every 3-5 years which puts them way ahead of Racket.
I'd also note that Chez Scheme was a commercial implementation bought and open-sourced by Cisco. It wasn't something they threw together. Because it is a complete scheme v6 implementation they are building on instead of rolling their own implementation in C. Coding against a stable Scheme API has to be easier and less buggy than what they had before (not to mention Chez being much faster at a lot of stuff).
I think you should read the old posts as to why Racket transitioned it's guts from primarily C to Chez Scheme. It would save a lot of time in the discussion here if you became familiar with that transition.
The short story is the same as anything written in C: it's an unwieldy language.
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.
