He  Daniel,<br><br> I use the Data.Map now, this makes it way more flexibler<br><br><br><div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">

data WordTree<br>
    = Branch [(Char, WordTree)]<br>
    | Tip<br>
<br></blockquote><div><br>I only don&#39;t use this type of Tree. I am not sure how it works, but it looks good, so I will experiment with it. Is it a so called rose tree? (Then I can find some articles about it). <br> </div>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div class="im"><br>
</div>Share the subtree,<br>
                        Just a -&gt; let st = buildTree cs r<br>
                                  in Choice (a,st) (c,st)<br>
<br></blockquote><div>Stupid thing not to do, think I overlooked it :) <br><br>Thanks again.<br><br>Edgar <br></div></div>