Do they really have better economics? (EDIT: ergonomics!)

Last time I looked into OCaml, I struggled to find a way to interact with the database in a type-safe way, I never figured out which standard library I was meant to install, I was being encouraged to use 2-3 different project management tools (Dune + Esy + OPAM), and I gave up on writing tests. But at least there's a garbage collector!

I realise these are all problems that I'll wrap my head around over time, and eventually they'll seem completely trivial to me, but the introductory documentation on getting started as a professional (and not as a first-year student doing a French-language compsci degree, which is what most of the documentation assumes), is pretty dire.

Meanwhile, much as I'm sure I overuse `.clone()` and `[A]Rc<_>`, the ownership model of Rust is deeply useful. It's something I often find myself missing in Javascript - not necessarily because I want to produce the most performant code, but because it's useful to understand the lifetimes of the objects I'm keeping around. Am I accidentally storing a reference to something in a closure that I forgot about? When this object gets deleted, have I checked that it's the last possible reference to this object? Etc.

Like, I don't think everyone needs to learn Rust. It's a great language, but there's lots of other great languages out there, depending on your personal and business contexts. But I think this idea that Rust can and should only be a low-level language feels absurd to me. It is a fairly ergonomic language with a fantastic ecosystem, a powerful type system, and an ownership model that will be useful even if you do try and opt partly out of it with GC-like wrapper types.

I guess you mean ergonomics.

Yes they do, unless you get your editor to magically type `.clone()` and `[A]Rc<_>` all over the place.

Not to mention they don't need unsafe, or 3rd party crates to handle graphs.

Additionally, all of them have interpreters and REPLs alongside their compilers, streamlining the code-develop-debug loop.

Thanks for pointing the typo out! I've fixed the comment.

In fairness, I think a lot of this comes down to familiarity. I'm fairly familiar with `.clone()` and Arcs at this point, so they don't really change much in terms of ergonomics. Usually their usage is fairly obvious, and quite often my editor literally does magically type the `.clone()` calls through LSP fix commands. It's the same as, say, OCaml's insistence that recursion is better for complex loops than, say, `while` — it's not necessarily wrong, but if you're unfamiliar with the idea, it's going to feel weird.

More important to me is the ergonomics of the broader ecosystem, and that's something that Rust has done well, that other languages just don't seem to be interested in at all. Things like integrating testing into the standard workflow; working hard on getting the stdlib in good condition; having an excellent ecosystem of well-documented, usable libraries; or designing error messages and lints with a focus on getting people to understand how the language works and not just what they've done wrong this time. I've really missed that stuff whenever I've tried MLs. You mention, for example, REPLs, but a unit test is basically a saved REPL session that you can repeat every time you make a change.

I'm not trying to convince anyone that Rust is the best language in the world or something. I really like it, but I find it helpful to think in terms of object ownership even in non-Rust languages, and I can understand why for other people that sort of approach is unhelpful. But I would love to see other languages embrace its ergonomics more, or new languages created with that as their focus.

A unit test has nothing to do with a REPL, a proper REPL provides something similar to jupiter notebooks in feel, alongside debugging and hot code reload experience.

Maybe we have different understandings of REPLs. For me, a REPL is a tool that I can use to try out some portion of my code, see how it responds to various inputs, see how it handles certain cases, and explore the internals of it via debugging tools.

But... that's what I do in a unit test anyway. A unit test is essentially a REPL session that I've frozen in time, can replay whenever I want, can debug, can trigger a fresh run whenever changes occur (which isn't quite hot reloading, but often a darn sight more useful), and can keep track of and share with my team. Which means I'm not just able to explore things on my own, but I can see the explorations that other people have made with their code.

For me the REPL is the experience similar to Lisp Machines, Smalltalk kind of experience, which is loosely captured in Jupiter Notebooks.

As for unit tests being more usefull, depends on how much one is willing to wait for them to run in Rust, given its compile times.