I don't think spark is easier to learn. Ada probably is. Ada sacrifices some performance for some of the benefits rust gets for free though, and deallocating memory is unsafe in the versions I've played with. If forbidding free is the way we choose to eliminate use after free, then there are a lot more memory safe languages.

Only if you never moved beyond Ada83.

Controlled Types and SPARK provide the mechanisms to deallocate only when it is actually safe to do so.

Additionally unbounded collections, are just like graphs in Rust, they provide safe ways to managed dynamically sized collections, while hiding the unsafe code in implementation.