Monomorphization

polymorphic functions are replaced by many monomorphic functions for each unique instantiation.^[1] It is considered beneficial to undergo the mentioned transformation because it results in the output intermediate representation (IR) having specific types, which allows for more effective optimization. Additionally, many IRs are intended to be low-level and do not accommodate polymorphism. The resulting code is generally faster than dynamic dispatch, but may require more compilation time and storage space due to duplicating the function body.^{[2][3][4][5][6][7]}

fn id<T>(x: T) -> T {
    return x;
}

fn main() {
    let int = id(10);
    let string = id("some text");
    println!("{int}, {string}");
}

fn id_i32(x: i32) -> i32 {
    return x;
}

fn id_str(x: &str) -> &str {
    return x;
}

fn main() {
    let int = id_i32(10);
    let string = id_str("some text");
    println!("{int}, {string}");
}