That's the "carry phantom types around" option, but it only gets you so far. If you never need to compute with the term, it's enough (see https://play.rust-lang.org/?version=stable&mode=debug&editio...).

You could use statically sized arrays, but if you can't have the static sizes of the arrays as your type parameters, but instead some arbitrary M and N, the size of your data structure isn't part of your type and you don't get the statically verified safety benefits. You also can't express M + N or anything of the sort.

Neither C++ nor Rust really hurt for expressivity, though.