/* Parametric types, C# 2.0 only  (also available with Java 1.5) */
using System;

public class cell<A>
{
  public A head;
  public cell<A> tail;  // can't have list with different type objects
  public cell(A h, cell<A> t) { head=h; tail=t; }
}// cell<A>

public class qlist0
{
   // naturally polymorphic function
   public static int length<A>(cell<A> L)
   {
      int ax = 0;
      while (L!=null) {L=L.tail; ax++;}
      return ax;
   }

   // artificially polymorphic function:
/*
   public static void dec<A>(cell<A> L) where A : somesuperclass
   {
      while (L!=null)
       {
          L.head = L.head - 1;
	  L=L.tail;
       }
   }
 */

 public static void Main()
 {
    cell<int> A = new cell<int>(2,new cell<int>(3,new cell<int>(5,null)));
    cell<double> B = new cell<double>(1.5,new cell<double>(3.4,null));
    cell<string> C = new cell<string>("ab",new cell<string>("cd",null));
    Console.WriteLine(length(A));
    Console.WriteLine(length(B));
    Console.WriteLine(length(C));
 }  // main

} // qlist0