static final class TArray<A> extends ArrayList<A> {
  Class<A> type;

  *() {}
  *(Class<A> *type) {}
  
  <B> TArray<B> cast() { ret (TArray) this; }

  public bool add(A a) {
    assertIsInstance(type, a);
    ret super.add(a);
  }
  
  public A set(int i, A a) {
    assertIsInstance(type, a);
    ret super.set(i, a);
  }

  // overwrite more methods?
}