!7

p-exp {

  pnl(iteratorToList(shuffledIterator(words("This is a very good test"))));

}

static <A> Iterator<A> shuffledIterator(final List<A> l) {

  return new Iterator<A>() {

    Random randomizer = new Random();

    int n = l.size();

    int i = 0;

    Map<Integer, A> shuffled = new HashMap();

    public boolean hasNext() { ret i < n; }

    public A next() {

      int j = i+randomizer.nextInt(n-i);

      A a = get(i), b = get(j);

      shuffled.put(j, a);

      shuffled.remove(i);

      ++i;

      return b;

    }

    A get(int i) {

      return shuffled.containsKey(i) ? shuffled.get(i) : l.get(i);

    }

  };

}