For people using scheme as a language this is a repository of a few scheme programs. Hope it helps you out. I'm not sure if all of them work but most of them do.This is just to get familiarised with the language and understand how codes could be written in MIT SCHEME. If you want to make any changes do put up a request and I'll get back to you. This might not be the best code or the best source but it surely gives an idea of how things are in scheme and how you can proceed with your four designs(for nitc students). For further knowledge do check out toycode.windroilla.com