Eigen, although often criticized for its long build times, is still the only linear algebra library that can lazy-evaluate and optimize expressions in compile-time, thanks to C++’s template metaprogramming.

In overall Rust’s current type system isn’t good enough to match what C++ has for numeric computations, although there have been some recent improvements such as the min-const-generics feature. I’ll probably try the language again once const generics are finished.