// file:    integers.java
// author:  Robert Keller
// purpose: test lazy evaluation using integers
// To test main use: java -cs integers

import polya.*;
import java.io.*;
import java.util.*;

class integers extends Growable
  {
  static public Polylist nats = Polylist.cons(new Long(0), 
                                 new Incremental(new integers(1)));
  // integers reuses the Growable

  long n;		// The numeric "seed" for the integers from n

  integers(long n)
    {
    this.n = n;
    }

  public Object grow()
    {
    Long value = new Long(n); 
    n++;
    return Polylist.cons(value, new Incremental(this));
    }

  public static void main(String[] arg)
    {
    System.out.println(nats);

    System.out.println(nats.prefix(10));

    System.out.println(nats);

    System.out.println(nats.prefix(20));

    System.out.println(nats);

    System.out.println(nats.prefix(20).coprefix(10));
    }
  }