// Rust's `&[T]` is a borrow, not a copy. Nim's view types model that,
// including returning one: writing through the view reaches the original.
fn head(xs: &[i32], n: usize) -> &[i32] {
    &xs[..n]
}

fn middle(xs: &[i32]) -> &[i32] {
    &xs[1..3]
}

fn sum(xs: &[i32]) -> i32 {
    let mut t: i32 = 0;
    for x in xs.iter() {
        t += x;
    }
    t
}

fn main() {
    let v: Vec<i32> = vec![1, 2, 3, 4, 5];
    println!("{}", sum(head(&v, 3)));
    println!("{}", sum(middle(&v)));
    println!("{}", head(&v, 2).len());
    println!("{}", head(&v, 5)[4]);
}