As of today, App.net is a freemium service(blog.app.net)

    def resume
      callcc do |cc|
        $current = self
        @caller = cc
        @resumer.call
      end
    end
    
    def self.yield
      callcc do |cc|
        $current.resumer = cc
        $current.caller.call(cc)
      end
    end

    memoize (f): ->
        cache = { }
        () ->
            h = hash arguments
            cache [h] ? (cache [h] = (f arguments))