Tnx for you comments. My example was wrong as Damien pointed out because sets are immutable and I was using them in a very wrong way. I got around the problem using an object with a mutable val. I don't think this is the best solution but I couldn't figure out how to do it with using simple records... attacched there is the code snippet... tnx. p On Mon, Jan 26, 2004 at 02:27:46PM +0100, Damien Doligez wrote: > If you really need mutable sets, maybe you should use the Hashtbl > module instead of Set. -- ++ Our capacity for understanding is inversely proportional to how much we think we know. The more I know, the more I know I don't know... ++ Please avoid sending me Word or PowerPoint attachments. See http://www.fsf.org/philosophy/no-word-attachments.html