How to use trait bounds

Use trait bounds to constrain generic types so they implement specific traits, ensuring the code can call those trait's methods. Place the bound after the generic type with a colon in function signatures or after the impl block for structs.

fn print_largest<T: PartialOrd + std::fmt::Display>(list: &[T]) {
    let largest = list.iter().max().unwrap();
    println!("The largest is {largest}");
}

For multiple bounds, separate them with a plus sign (+). Use the where clause for complex constraints or when the signature becomes too long.

fn print_largest<T>(list: &[T])
where
    T: PartialOrd + std::fmt::Display,
{
    let largest = list.iter().max().unwrap();
    println!("The largest is {largest}");
}

Trait bounds are like a job requirement list for your code. You tell Rust that a generic placeholder must be able to do specific things, like being printable or comparable, before you use it. This prevents errors by ensuring the code only runs on types that support the actions you need.