!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);
    }
  };
}