On Monday, March 24, 2003, 3:35:23 PM, Julian wrote: > Or have I misinterpreted the problem? It seems too trivial to be a > "show me that this is possible" kind of problem... :-( Thanks for the solution. You didn't misunderstand the problem, nor did I doubt it was possible. But Jim mentioned that walking two lists in parallel was a special case that Ruby's iterators don't handle very gracefully. So I wanted to see what "the Ruby way" was. Thanks also for reinforcing that I shall never understand continuations! Gavin