proceedable exceptions in ruby

proceedable.rb

require "continuation"

module  Proceedable
  class ProceedableException < Exception

    def initialize(msg, cont)
      super(msg)
      @cont = cont
    end

    def proceed
      @cont.call()
    end

  end

  def throw(msg)
    callcc {|cont| raise ProceedableException.new(msg, cont) }
  end
end

include Proceedable

def a
  throw "boom"
  puts "after boom"
end

def b
  a()
end

begin
  b()
rescue ProceedableException => e
  puts "caught #{e}"
  e.proceed
end