I think my favorite thing is the `…` operator. Go check it out. It’s not like the splat operator in other languages, though it does give that feel initially. It’s much more general: it works with nested data structures and can take the place of a `map` operation.

The best part of `…` is that it is not a built-in thing—it’s just a macro! The magic is that Rhombus lets you define different macros depending on whether or not the macro identifier appears in binding context (left side of `=`), expression context, or some other contexts. IIRC you can even define your own contexts too.

Rhombus takes the best-in-class macro system of Racket and somehow finds a way to improve upon it. I say this after researching and comparing detailed metaprogramming features across a dozen different languages. Rhombus is a very neat little language.

Last thing: Rhombus’ main data type, the list, is implemented with an RRB tree. RRB trees support structural sharing, functional updates, and have O(log n) iterate, insert, delete, append, and arbitrary read operations. The constant factor on that is tiny: I think it’s like log_16 or log_32. They’re designed to be very cache friendly. Super cool data structure.

Anyway, my main initial concern was how to make good macros without s-expressions. There is a nice video by Matthew Flatt in RacketCon 2023. The first 6 minutes and 20 seconds are internal stuff, so skip to the 380s that I added in this link: https://www.youtube.com/watch?v=OLgEL4esYU0&t=380s He takes like another 6 minutes to explain the general idea and make some wishes, and then at the 12m mark he defines macros in Rhombus and makes the wish real in just 2m (with some enhancements later).

"Modern programming languages reflect a consensus on the most important programming concepts, including lexically scoped variables, closures, objects, pattern matching, and type parametricity. Why, then, yet another programming language?"

I love this as a start. More programming languages need to start the conversation this way.

However, it whiffs after this when it fails to answer the question. Or at least fails to answer it in a way I understand. The next paragraph should not start with "Beyond the basics, there are still more good ideas for programming constructs than can fit in any one language specification." - cut straight to what the "programming constructs" are.

This section ends with "approachable" and "extensible". These are nothing. When considering the reasons for a language, look at the negation. Nobody writes a language to be "unapproachable"... well, unless you're on the esolang wiki, but that's not really what we're talking about here. Nobody really wants to stick "non-extensible" on their language either... where we all disagree is in the how one extends things. As someone reading this screen to decide if I'm interested these attributes mean nothing to me.

The page does get around to making it clear that there is a huge focus on macros, which is something, but it takes a while to get there.

That's a legitimate selling point. It's especially a selling point if you can explain clearly how this is different from just using Scheme directly. I have no idea if your language does this but I've long thought that it would be interesting to have a macro-focused language that went all-in on making them debuggable. Have the language compiler and runtime support dynamically exploring them, expanding them in your editor, re-contracting them, full debugging support, just go all-in on supporting that work flow. That would be an example of that sort of thing.

Summer Rhombus picture competition 2026 - https://news.ycombinator.com/item?id=48546270 - June 2026 (2 comments)

Rhombus Language - https://news.ycombinator.com/item?id=43394881 - March 2025 (158 comments)

Rhombus: Macro-extensible language with conventional syntax built on Racket - https://news.ycombinator.com/item?id=41151439 - Aug 2024 (97 comments)

State of Rhombus (programming language) - https://news.ycombinator.com/item?id=30314109 - Feb 2022 (17 comments)

How do I distribute my Rhombus programs? Can I cross compile to other architectures/OSs, ideally with a static binary?

What about libraries? Is there a good package manager? I presume from the post that the library ecosystem is pretty immature (maybe the Racket ecosystem is larger). Can I easily build a CRUD web app?

Is concurrency easy to make correct? Are tests easy to write? Tests involving concurrency? Race detection?

Dev experience: is it statically typed? I couldn't really tell from a quick search. Will the build system make a fast feedback loop for me and LLMs? Is it IDE friendly (auto complete, find all references, etc)? Is there language server support so I can bring my own editor? Will the macros mean I have to learn a bunch of DSLs to use anyone's library? Do the DSLs have IDE support?

Wow that's a lot of questions ;) It looks like a fun language in any case. And the fact that its even possible to make a Pythonic language on top of a LISP is its own showcase for Racket's power

https://docs.racket-lang.org/shrubbery/index.html

https://carolina.codes

* approachable and easy to use for everyday purposes, with a readable indentation syntax; and

* uniquely customisable with an _open-compiler API_ that is accessible to a wide audience.

    fun repeat(str :: String, n :: Nat) :: List:
        [body]

    fun repeat(str: String, n: Nat): List = 

* - https://parentheticallyspeaking.org/articles/bicameral-not-h...

† - https://docs.racket-lang.org/shrubbery/index.html?fam=Rhombu...

I don't want to be too nitpicky but ... the sentence has two "the", aka "the the most important". It is a really irrelevant error, but on the other hand, has nobody ever read the documentation through slowly, before publishing? Because then this means lack of care and interest. Again, people make typos, that's ok, but if you try to promote a new language, you should at the least have read your own (!!!) writing once. And I am quite certain that the author has not bothered to check his own primary writing here, not even once. So why would he then expect others to want to use a new programming language? Sure, that typo means nothing at all about the programming language itself, but as I got older I also realised that many great language designers are horrible at writing documentation. I'd much rather use languages that are very well documented. Naturally this is a tiny issue here, but if you don't even care about typos in the primary introduction, it makes one wonder about the long term focus of the language as such.