Haskell has higher-kinded type parameters and Idris has dependent types. But SML and OCaml don't even have typeclasses at all, much less higher kinds.
Furthermore, what makes Rust's type system interesting isn't just its use of regions (which the ML Kit used); it's regions combined with inherited mutability plus the borrow check to maintain soundness.
OCaml has a powerful module system, labeled and optional function parameters, row polymorphism, equirecursive types, and GADTs. Most of these features would be fairly difficult to add to Rust.
OCaml also has a better track record with soundness issues than Rust, and more interesting fragments of the language have been formalized.
There is a fun library[0] with a pretty good paper[1] on how to do that in OCaml :-)
[0]: https://github.com/ocamllabs/higher
[1]: https://ocamllabs.github.io/higher/lightweight-higher-kinded...
GHC 8.0 almost has dependent types and the expectation is feature completeness in 8.2, thought what's in 8.0 is already useful.
I like and use Rust and the design decisions that led to a very capable region system that allows one to write data race free and memory correct code is excellent. Haskell doesn't have such a thing because it doesn't try avoid GC.
I didn't do a point by point comparison of Rust expressiveness vs Haskell recently, but I don't remember it being close. Rafael might need to write a Rust for for Haskellers as an update of his "for OCamlers" post a while back.
It is a bit outdated but as far as I can see not inaccurate yet. I only plan to update it when HKTs make it to Rust.