Ownership and borrowing are also useful for avoiding data races. OCaml solves the problem by not having any shared state at all, which is obviously a huge limitation.
Current OCaml needn't worry about data races since no state is shared. Unfortunately, current OCaml also only exploits a single core, but it's so insanely fast that usually doesn't matter.
Upcoming OCaml multicore solves the shared state and data races problem with algebraic effects[0]. It is working, it's just not yet been released in mainline OCaml. Supposedly, that will happen this year, but we'll see.
0. http://kcsrk.info/ocaml/multicore/2015/05/20/effects-multico...
OCaml seems like the argument against Rust's claim to trade usability for safety. It's not true for everything, I wouldn't write embedded OCaml, but it's an easy disproof-by-example for "Rust's difficulty is the inevitable price for trustworthy code!"
Which isn't to say OCaml is trivial, or Rust is useless (GC and threading both being limitations). It just makes me skeptical of claims that Rust's difficulty is irreducible.
Rust's difficulty relative to OCaml might be irreducible if we consider the difficulty added by not providing a pervasive GC, which is part of Rust's design goal and not part of OCaml's.
Re:The struggle with Rust
by Ar-Curunir on Tuesday January 24, 2017 @12:03PM
(#13473140)
But OCaml isn't intended for the use cases Rust is intended for: a replacement for C and C++
It depends on the use cases you mean.
OCaml is actually used for many systems programming tasks that can live with a tracing GC.
Re:The struggle with Rust
by GregBuchholz on Tuesday January 24, 2017 @12:19PM
(#13473332)
>I wouldn't write embedded OCaml
But you can run OCaml on a microcontroller:
You don't think the OCaml type system would do this? OCaml gives you just as much safety as Rust does, it just doesn't also give you no GC like Rust does. And the price Rust pays for the absence of GC is the lifetime concept, which adds a very significant layer of complexity to the language. Much like OCaml, Swift and Scala also provide very safe type systems.
Again, if you can't have a GC, then Rust is an excellent option, and the only really safe GC-less language unless you use C with FramaC or similar static analysis (and FramaC also requires lots of training and time to use, just like Rust).