Rust add function using any parameter type.

add.rs

extern crate num;
use num::{ToPrimitive, Float};

fn add<T, R, U>(a: T, b: R) -> U
    where 
        T: ToPrimitive,
        R: ToPrimitive,
        U: Float,
    
{
    U::from(a).unwrap() + U::from(b).unwrap()
}

fn main() {
    let b:f64 = add(8, 7.76);
    let b:f32 = add(8, 8);
    println!("{}", b);
}