/**
 * FunList FrameWork.
 * @dependency IFunAlgo 
 */
public abstract class FunListFW {

  public abstract Integer car();
  public abstract FunListFW cdr();
  public abstract Object execute (IFunAlgo algo, Object input);

}

public class EmptyFW extends FunListFW {

   private static EmptyFW _instance = new EmptyFW ();

   private EmptyFW () {
   }

   public static EmptyFW Singleton () {
      return _instance;
   }
   
  public Integer car() {
    throw new java.util.NoSuchElementException ("Empty has no element.");
  }

  public FunListFW cdr() {
    throw new java.util.NoSuchElementException ("Empty has no tail.");
  }

  public Object execute (IFunAlgo algo, Object input) {
      return algo.forEmpty (this, input);
   }
}

public class ConsFW extends FunListFW {

  private Integer _car;
  /** @SBGen Variable (,,,64)   */
	private FunListFW _cdr;

  public ConsFW( Integer car, FunListFW cdr ) {
    _car = car;
    _cdr = cdr;
  }

  public Integer car() {
    return _car;
  }

  public FunListFW cdr() {
    return _cdr;
  }

  public Object execute (IFunAlgo algo, Object input) {
      return algo.forCons (this, input);
   }
}

/**
 * @dependency FunListFW uses
 */
public interface IFunAlgo {
   public abstract Object forEmpty(EmptyFW list, Object input);
   public abstract Object forCons(ConsFW list, Object input);
}

public class SumAlgo implements IFunAlgo {
   private static SumAlgo _instance = new SumAlgo ();

   private SumAlgo () {
   }

   public static SumAlgo Singleton () {
      return _instance;
   }

   public Object forEmpty (EmptyFW list, Object input) {
      return new Integer (0);
   }

   public Object forCons (ConsFW list, Object input) {
      Integer carInt = list.car ();
      Integer tailSumInt = (Integer)list.cdr ().execute (this, null);
      return new Integer ( carInt.intValue () + tailSumInt.intValue ()); 
   }
}

/**
 * @dependency FunListFW uses
 * @dependency IFunAlgo uses
 */
public class Client {

   public static void main (String[] args){
      FunListFW l = new ConsFW (new Integer (5), EmptyFW.Singleton ());
      System.out.println ("Sum is " + l.execute (SumAlgo.Singleton (), null));
      try {
         System.out.println ("Press Enter to quit...");
         System.in.read ();
      }
      catch (Exception e){
      }
   }
}