num

num crate for number types and traits

The Rust num crate is a collection of numeric types and traits for Rust. This includes new types for big integers, rationals (aka fractions), and complex numbers, new traits for generic programming on numeric properties like Integer, and generic range iterators.

Example of the PrimInt trait for primitive integers, which helps with generic traits and monomorphism:

pub trait FizzBuzz {
    fn fizzbuzz(&self) -> String;
}

impl<T> FizzBuzz for T
where 
    T: num::traits::int::PrimInt,
    T: std::fmt::Display,
{
    fn fizzbuzz(&self) -> String {
        let t0 = T::zero();
        let t3 = T::from(3).unwrap();
        let t5 = T::from(5).unwrap();
        match (*self % t3 == t0, *self % t5 == t0) {
            (true, true) => String::from("FizzBuzz"),
            (true, _) => String::from("Fizz"),
            (_, true) => String::from("Buzz"),
            _ => format!("{}", self),
        }
    }
}

fn main() {
    for i in 1..=100 {
        println!("{}", i.fizzbuzz())
    }
}