And btw. it is not an "artificial problem".

I personally believe that I meant "not an actual problem of mine". Of course it may be an actual problem of someone else...

Thank you for the supplied information. I'd still be interested in ways to do it with Perl. In fact it's true that the abstract algorithm could be implemented in any sufficiently powerful language. But some languages have syntactical features that make some taks particularly easy or difficult to implement... How can Perl specifically come to the rescue in this regard?