webapp.rb

require 'rack'

class Object
  def webapp
    tap {
       def self.call(env)
         func, *attrs = env['PATH_INFO'].split('/').reject(&:empty?)
         [200, {}, send(func, *attrs)]
       end
    }
  end
end

Rack::Handler::WEBrick.run [].webapp, Port: 9292
#                         ^^^^^^^^^^^
#                              |          (x)
#                         ROFLSCALE DB ---/
#


# http://localhost:9292/push/1  -> 1
# http://localhost:9292/push/2  -> 12
# http://localhost:9292/push/3  -> 123

# http://localhost:9292/to_a    -> 123

# http://localhost:9292/pop     -> 3
# http://localhost:9292/shift   -> 1

# Implementations in other languages (thanks guys!):
# Node.js: https://gist.github.com/700995
# Groovy: https://gist.github.com/702337
# Python: https://gist.github.com/702001