Shared via Rust Playground

playground.rs

fn main() {
    // I don't want this to have to be mut.
    let v = vec![1, 2, 3];
    // Not this either.
    let w = vec![3, 4, 5];
    
    // I want a newly allocated vec that is v + w.
    let x = vec_concat(&v, &w);
    
    println!("{:?}", x);
    
}

fn vec_concat(vec1: &Vec<i32>, vec2: &Vec<i32>) -> Vec<i32> {
    let mut result = vec1.clone();
    result.extend(vec2.iter().cloned());
    result
}