> The only legitimate complaint there is that it's tough in Rust to get two arbitrary mutable slices into the same array. Rust wants to be sure they're disjoint, to prevent aliasing. For some matrix manipulation, this is inconvenient.

I've only looked into Rust briefly, but I thought this was the point of unsafe blocks? You can roll your own multi-dimensional array data structure using unsafe blocks if you're certain what you're doing is actually safe.