Sinatra-MVC.rb

require 'rubygems'
require 'sinatra'

class WelcomeController
  @@controller = self.new

  def self.method_missing(name, *args)
    @@controller.send(name)
  end

  def index
    "WelcomeController#index"
  end
end

class Router
  def self.route(&block)
    return unless block

    block.call(Router.new)
  end

  def method_missing(name, *args)
    Kernel.send(:get, "/#{name}") do
      WelcomeController.index
    end
  end
end

Router::route do |map|
  map.welcome :controller => :welcome, :action => :index
end