use "basic_models.g";

struct Null { };
class DataNode<T>;

union Node<T> {
  Null* null;
  DataNode<T>* node;
};

class DataNode<T> where { Regular<T> }
{
  DataNode(T d, Node<T>* n) : data(d), next(n) { }
  ~DataNode() { delete next; }
  Node<T>* next; /* pointer required, no recursion allowed. */
  T data;
};

fun nil<T>(T x) -> Node<T>* @ {
  return new Node<T> { null = new Null {} };
}

fun main() -> int@ {
  let n = @DataNode<int>(1, nil(1));
  return n.data - 1;
}