Safe memory management without a garbage collector.
> If Ocaml solves the problem why Rust?
Ocaml doesn't solve every problem any more than Rust does. Rust may solve a subset of the problems people use the listed languages for better than those languages, so it might be beneficial for people to use it in those cases.
> Rust was made to solve the problem Ada solves.
Not all solutions have the same efficiency, or are as easy to understand. Rust aims to enforce safety at compile time to eliminate runtime safety checks where possible. Ada performs many safety checks at runtime, which introduces a performance cost. This does allow Ada to provide some additional safety checks though (such as limiting a type/subtype to a range of values).
It has [ ] nothing where a garbage collector would be. ML is beautiful language. I am not trying to get anyone to stop speaking their language of choice, but I am trying to get people who need to do systems-y things to use Rust. There are more similarities between the Rust programmer and the OCaml programmer than there are differences.
