sleeping barber in elixir

sleeping_barber.exs

module Barber
  def loop(shop_pid)
    shop_pid <- 'barbercheck
    receive
    match 'wakeup
     IO.puts "wakeup"
      loop(shop_pid)
    match {'customer, customer}
      cut_hair(shop_pid, customer)
      loop(shop_pid)
    end
  end

  def cut_hair(shop_pid, customer)
    IO.puts "cutting customer #{customer}"
    shop_pid <- {'cut, customer}
    IO.puts "customer #{customer} turned into shepherd's pie"
  end
end

object Shop
  def initialize
    shop_pid = Process.current
    barber_pid = Process.spawn -> Barber.loop(shop_pid)
    @('barber_pid: barber_pid, 'shop_pid: shop_pid)
  end

  def loop(customers_in_chairs)
    IO.puts "shop loop #{customers_in_chairs}"
    receive
    match {'cut, customer}
      if customers_in_chairs.include?(customer)
        loop(customers_in_chairs.delete(customer))
      else
        loop(customers_in_chairs)
      end
    match 'barbercheck
      IO.puts "barber checking ..."
      respond_to_barber(customers_in_chairs)
    match {'customer, customer}
      IO.puts("new customer #{customer}")
      add_customer(customers_in_chairs, customer)
    match any
       IO.puts "matching anything #{any}"
    end
  end


  def add_customer(customers_in_chairs, customer)
    if customers_in_chairs.size > 3
      loop(customers_in_chairs)
    else
      @barber_pid <- 'wakeup
      loop([customer|customers_in_chairs])
    end
  end

  def respond_to_barber([])
    IO.puts "no customers"
    loop([])
  end
  def respond_to_barber([head|tail])
    @barber_pid <- {'customer, head}
    loop(tail)
  end
end

pid = Process.spawn -> Shop.new.loop([])
IO.puts pid
pid <- {'customer, "hello"}

what doesn't work: the 'barbercheck message never seems to arrive to the shop

and it works now, thanks Jose :)