#[derive(Copy, Clone)]
struct NodeUnit;
#[derive(Copy, Clone)]
struct Node<S: Copy> {
    stack: S
}

impl NodeUnit {
    fn init() -> Node<(NodeUnit)> {
        Node { stack: (NodeUnit) }
    }
}

impl<S> Node<S>
where
    S: Copy,
{
    fn push<N: Copy>(self, next: N) -> Node<(N, S)> {
        Node { stack: (next, self.stack) }
    }
}

impl<C, P> Node<(C, P)>
where
    C: Copy,
    P: Copy,
{
    fn peek(&self) -> &C {
        &self.stack.0
    }

    fn pop(self) -> Node<P> {
        Node { stack: self.stack.1 }
    }
}

#[derive(Debug)]
struct MyObject {
    value: u8,
}

fn main() {
    let obj1 = MyObject { value: 0 };
    let obj2 = MyObject { value: 1 };
    let n = NodeUnit::init();
    let n2 = n.push(&obj1);
    let n3 = n2.push(&obj2);
    println!("{:?}", n3.peek());

    let n2 = n3.pop();
    println!("{:?}", n2.peek());
}