Rust's borrow checker can prevent data races, but it can't prevent deadlocks.
The Pony language has something analogous to Rust's ownership system (there it's called reference capabilities [0]), but in addition to that Pony prevents deadlocks too [1]. It does so by not providing locks, but only providing actors with message passing (channels). Now, Pony is a much higher level language and unsuitable for some of the low level stuff that Rust does.
If you restrict your Rust program to not use locks, but just send messages through channels between threads [2], you won't have deadlocks either. But that's quite a handicap for a low level systems language, so Rust in general can't commit to that.
[2] If you would rather prefer to write async code, there are async channels too, but to be deadlock-free you need to always guarantee that your futures are polled https://rust-lang.github.io/wg-async/vision/submitted_storie... which is maybe a strange requirement that's alien to most languages
> If you restrict your Rust program […] you won't have deadlocks either.
So Rust is directly superior, because it gives you a choice? I get it, there is something nice about having an enforced paradigm, so you're not forced to work with foreign 'bad' code, but I don't understand your argument:
> But that's quite a handicap for a low level systems language, so Rust in general can't commit to that.
Rust is fast, so it can't afford being slow. Pony solved this problem by being a slow, high-level language, so now it can block fast solutions and get away with it, because it's slow anyway, and therefore it's presented as a superior alternative to Rust - which can do the exact same thing, and have at worst the same speed as Pony, but we expect more from Rust (because it's better) therefore it's worse? Just doesn't make sense to me, sorry :D
Again, I see the advantage in the aspect of a language being simpler, and enforcing a paradigm on the ecosystem so developers have less head scratching to do when cooperating.
What's nice about Rust is that it enforces a safe paradigm at first, but over time one learns Rc, RefCell, unsafe "rustonomicon" to be able to optimize. In *the* Rust book, channels are taught first, immediately at the beginning of the chapter about threads.
The Pony language has something analogous to Rust's ownership system (there it's called reference capabilities [0]), but in addition to that Pony prevents deadlocks too [1]. It does so by not providing locks, but only providing actors with message passing (channels). Now, Pony is a much higher level language and unsuitable for some of the low level stuff that Rust does.
If you restrict your Rust program to not use locks, but just send messages through channels between threads [2], you won't have deadlocks either. But that's quite a handicap for a low level systems language, so Rust in general can't commit to that.
[0] https://tutorial.ponylang.io/reference-capabilities/referenc...
[1] https://www.ponylang.io/discover/#what-makes-pony-different
[2] If you would rather prefer to write async code, there are async channels too, but to be deadlock-free you need to always guarantee that your futures are polled https://rust-lang.github.io/wg-async/vision/submitted_storie... which is maybe a strange requirement that's alien to most languages