fn f<T>(a: [T; 5], b: [T; 5]) -> [T; 10]
where
    T: Copy + Default,
{
    let mut c = [T::default(); 10];
    c[..5].clone_from_slice(&a[..]);
    c[5..].clone_from_slice(&b[..]);
    c
}

fn g<T: Copy>(a: &[T], b: &[T]) -> Vec<T> {
    let mut c = Vec::with_capacity(a.len() + b.len());
    c.extend(a);
    c.extend(b);
    c
}

fn main() {
    let a = [0,1,2,3,4];
    let b = [5,6,7,8,9];
    let c = f(a, b);
    let d = g(&a[..], &b[..]);

    for c in (b'a'..b'z').chain(b'A'..b'Z').chain(b'0'..b'9') {
        print!("{}", ::std::char::from_u32(c as u32).unwrap())
    }
}