How does this scheme of yours work with m/s and seconds.
IIUC, rust would NOT let you do a type checked m/s * s => m, so using the type system for these kinds of games is silly and dangerous (I presume you would have to do the dumb thing and typeconvert to the same type -- e.g.
(m) (speed * ((m/s) seconds))
That's no problem in Rust. You can have a Speed type and a Time type, and define the multiplication operator over them to return a Length value. In fact, there's already a library which does exactly that, with tons of predefined SI units: https://docs.rs/uom/latest/uom/
And the exact same thing can be done in C++.