title: how to match regex route in Sinatra?
body: <p>i'm trying to make this code snippet from the sinatra tutorial work so that I can set some routes based on regex matching.  it doesn't seem to be working and I'm copy pasting direct from the tutorial, any ideas on what i'm missing.  make the assumption that my sinatra app is working and i have other correctly structured GET routes working so I'm unclear why a direct copy past like this doesn't work.  </p>
  
  <pre><code>get %r{/hello/([\w]+)} do
      "Hello, #{params[:captures].first}!"
  end
  </code></pre>
  
  <p>should correct map a route for <code>http://0.0.0.0:4567/hello</code> but is routing to a 'sinatra doesn't know this ditty' error message.  </p>
  
  <p>Thks.  </p>