/*
  Implements an integer list via inheritance

  See TIJ page 181 and JIAN page 64

  NOTE: we are unable to redefine head() because
  we get a clash. IntList is a kind of List, therefore
  the head() method is inherited and must have same return type.
  We cannot redefine head() to deliver different return type,
  so we have a intHead() method. This seems to go against the
  polymorphic grain!

  */

public class IntList extends List {

  public IntList(){
    super();
  }

  public IntList(int e) {
    super(new Integer(e));
  }

  public IntList(int e, IntList tail) {    
    super(new Integer(e), tail);
  } 

  public IntList add(int e) {
    return new IntList(e,this);
  }

  public int head() {
    return ((Integer)data).intValue(); // won't compile!!
  }
    
}