Thanks everyone, for the answers.<br>
<br>
I didn&#39;t knew the  <b>elem</b> function. That will make my life easier.<br>
<br>
For the sake of simplicity, I changed the code to a shorter <br>
<i>userRegistration</i> function, eliminating the <i>checkUser</i> function:<br>
<br>
<br>
<blockquote style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex; font-family: courier new,monospace;" class="gmail_quote">
  <div style="margin-left: 40px;">userRegistration user list<br>
    | elem user list = list<br>
    | otherwise = user:list<br>
  </div>
</blockquote>
<br><br>
It did worked fine.<br><br>
I&#39;m glad that I can count with this list in my learning process.<br>
<br>
Thanks again.<br>
<br>
<br>-- <br>____________________________________________________________________________<br>Francisco Borges &quot;Chicão&quot; Junior<br>..........................................................................................<br>
<a href="http://pedepinico.blogspot.com">http://pedepinico.blogspot.com</a><br>..........................................................................................<br>&quot;Quem de boa vontade carrega o difícil, também carrega o menos difícil...&quot; Lao Tsé - Tao Te Ching<br>
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