This is how a template might look like:

  <table border=1>
    <!-- TMPL_LOOP rows -->
      <tr>
        <!-- TMPL_LOOP cols -->
          <!-- TMPL_IF colorful-style -->
            <td align="right" bgcolor="pink"><!-- TMPL_VAR content --></td>
          <!-- TMPL_ELSE -->
            <td align="right" ><!-- TMPL_VAR content --></td>
          <!-- /TMPL_IF -->
        <!-- /TMPL_LOOP -->
      </tr>
    <!-- /TMPL_LOOP -->
  </table>

And this could be the corresponding Lisp code:

  (let* ((rows (loop for i below 49 by 7
                     collect (list :cols
                                   (loop for j from i below (+ i 7)
                                         for string = (format nil "~R" j)
                                         collect (list :content string
                                                       :colorful-style (oddp j))))))
         (values (list :rows rows)))
    (fill-and-print-template #p"/tmp/foo.tmpl" values))