concurrent_futures.rb

#!/usr/bin/env ruby
require 'celluloid'

class Futurer
  include Celluloid

  def wait(seconds)
    sleep seconds
    seconds
  end

  def print_future(future)
    puts future.value
  end

  def print_future_values_as_they_come_in
    futures = [3, 1, 2].map do |seconds|
      future.wait(seconds)
    end

    futures.each do |future|
      async.print_future(future)
    end
  end
end

Futurer.new.print_future_values_as_they_come_in

sleep