Concurrent Hello world in ruby with Celluloid, an actor library

gistfile1.rb

require 'celluloid'                                                                                                                                                           
                                                                                                                                                                              
class Hello                                                                                                                                                                   
  include Celluloid                                                                                                                                                           
                                                                                                                                                                              
  def say_hello                                                                                                                                                               
    "hello"                                                                                                                                                                   
  end                                                                                                                                                                         
                                                                                                                                                                              
end                                                                                                                                                                           
                                                                                                                                                                              
class World                                                                                                                                                                   
  include Celluloid                                                                                                                                                           
                                                                                                                                                                              
 def initialize                                                                                                                                                               
    wait_for_hello!                                                                                                                                                           
  end                                                                                                                                                                         
                                                                                                                                                                              
  def say_world                                                                                                                                                               
    "world"                                                                                                                                                                   
  end                                                                                                                                                                         
                                                                                                                                                                              
  def wait_for_hello                                                                                                                                                          
    loop do                                                                                                                                                                   
      message = receive { |msg| msg.is_a? String }                                                                                                                            
      puts "#{message} #{say_world}"                                                                                                                                          
    end                                                                                                                                                                       
  end                                                                                                                                                                         
                                                                                                                                                                              
end                                                                                                                                                                           
                                                                                                                                                                              
hello = Hello.new                                                                                                                                                             
world = World.new                                                                                                                                                             
                                                                                                                                                                              
100.times do               
 world.mailbox << hello.say_hello                                                                                                                                            
end