In analyzing my data I wanted to classify it with a naive Bayesian classifier. I wasn't sure I had the math right, so I wrote a tiny abstract classifier to test with. The code is pretty cool:
These twenty video lectures by Hal Abelson and Gerald Jay Sussman are a complete presentation of the course, given in July 1986 for Hewlett-Packard employees, and professionally produced by Hewlett-Packard Television.
In learning to write Scheme macros, I have noticed that it is easy to find both trivial examples and extraordinarily complex examples, but there seem to be no intermediate ones. I have discovered a few tricks in writing macros and perhaps some people will find them helpful.