Typenum is a Rust library for type-level numbers evaluated at compile time. It currently supports bits, unsigned integers, and signed integers.
For the full documentation, go here.
Here is a short example of its use:
use std::ops::Add;
use typenum::consts::{N2, P3, P4};
use typenum::int::Integer;
use typenum::Pow;
type X = <P3 as Add<P4>>::Output;
assert_eq!(<X as Integer>::to_i32(), 7);
type Y = <N2 as Pow<P3>>::Output;
assert_eq!(<Y as Integer>::to_i32(), -8);