I'm curious what this user community would come up with in order to implement the curious zigzag data structure. If you haven't heard anything about it, its a simple but peculiar idea, by the guy who dreamed up the Xanadu project: http://xanadu.com/zigzag/. Conceptually it is "cells" with some sort of value, where each cell has any number of connections to any other cell, but the connections are conceptually labeled/grouped as though they were dimensions. So a cell with the value "Brian McQueen" would have a link to "dorky guy" in the Description dimension, and a link to "519 S. Frances" in the Street Address dimension. Obviously most people would have links in those same dimensions passing through their own name's cell. My cell might have a pointer to "Hector" in the Hero dimension while a conceited man might have a link right back to itself in that same Hero direction. So the structure is very flexible. There are interesting examples on the web site of a Day Planner type of an app where each day has a time line and each time has appointments and the appointments have attendees and they all have personal contact information ... But its all logically linked. I imagine it would be something like this in C-like code: struct cell { value; ptr_to_links }; struct link { { dimension; ptr_to_destination; ptr_to_link; }; struct dimension { name; id; } ; As I write this I realise that I don't remember much, if any, discussion in this group about data structures. I may be starting with a non-functional way of thinking. BTW I'm mostly still at the reading Haskell and fiddling with ghci phase. Brian McQueen