{eyou:channel type="top" id="field" currentstyle="cur"} 
  <li class="{$field.currentstyle}">
  {$field.typename}
  {eyou:notempty name="$field.children"} 
   {eyou:channel name="$field.children" id="field2"} 
   <a href="{$field2.typeurl}">{$field2.typename}</a>
   {/eyou:channel} 
  {/eyou:notempty}
 </li>
{/eyou:channel}