Luminate CMS: How to render a list of CMS items with a date field grouped by month?

grouped-by-date.html

<t:if test="length > 0">
  <t:set id="lastdate" value="''" />
  <t:list>
  <t:if test="month(date) != lastdate"><h3><t:value id="date" format="MMMMMMMMM" /></h3></t:if>
  <a href="${url}">${title}</a>
  ...
  <t:set id="lastdate" value="month(date)" />
  </t:list>
 </t:if>