The difference between pub in Rust and _/__ in Python isn't that big. It's like Go that uses a capital letter to say what code is public. There's also a difference in philosophy between public by default and private by default. All in all, it's a small detail and doesn't affect things.

Sure, business logic is more readable in something like OCaml than in Rust. On the other hand, Rust isn't really worse than something like Java, and I like having more information than what you have in Python. I'll also add that Rust is often chosen for speed and reliability, and that part of that syntax is here to guarantee that. It's not directly business logic in the traditional sense, but it's something you expect from your code.

All in all, Rust is still not at the level of the "platonic ideal for syntaxes", especially not for most of the code I write (business logic for web apps, which wouldn't need Rust's speed). Still, in the realms of programming languages that are used, it's one of the best.

> The difference between pub in Rust and _/__ in Python isn't that big.

FWIW `__` doesn't mean "this is part of the implementation", it means "I'm designing a class for inheritance and I don't want child classes to stop on my attributes".

> Both Julia and Python has a concept of public and private code, neither have a pub keyword.

No. Python certainly does not have a concept of private code[0]. The Python community has a suggestion of things being implementation details.

Surely you can see that absolutely would not be good enough for a language which strives for static correctness? And even more so as the soundness of `unsafe` blocks often relies on the invariants of the type it's used in?

[0] well that's not entirely true, I guess there's native code.