title: POST request with no page refreshing in Yesod
body: <p>The task is to create a registration form with pretty error handling.<br>
  I'm a newbie in Yesod, so the only way I found to do this is:</p>
  
  <pre><code>regForm :: Form User
  
  getRegRExtra extraFormWidget = do
    (formWidget, enctype) &lt;- case extraFormWidget of
                               Nothing -&gt; generateFormPost regForm
                               Just val -&gt; return val
    defaultLayout $ $(widgetFile "reg/reg")
  
  getRegR = getRegRExtra Nothing
  
  postRegR = do
    ((result, widget), enctype) &lt;- runFormPostNoToken regForm 
    case result of
      FormSuccess person -&gt; undefined
      _ -&gt; getRegRExtra (Just (widget, enctype))
  </code></pre>
  
  <p>But there is a problem: Page refreshes on every submit while I want it to do this dynamically.<br>
  I know it could be fixed with the help of Ajax or Jquery,<br>
  but I'll lose all the benefits I get while using Yesod POST functions.<br>
  Is there any standard way to deal with that?</p>