Rubinius: how to create a counter as an official way?

I have this simple code to create a lazy array:

lazy_arr = Enumerator.new { |y|
    i = 1
    loop {
        y << i
        i+=1
    }
}
p lazy_arr.take(5)

In official Ruby 1.9.3, the output [1,2,3,4,5]I want.

But in Rubinius it gives an error and says that I cannot find the Enumerator constant.

So, I looked through it and found the Enumerator defined in the module Enumerableinstead kernel, and when it is generated, it needs several arguments in brackets: http://rubydoc.info/github/evanphx/rubinius/master/Enumerable/Enumerator

I tried changing Enumerator.newto Enumerable::Enumerator.newor include Enumerable, but does not work, because it needs more arguments.

How can I make an example above in Rubinius? Is there any way around code in both official and Rubinius?