> To that end, you should build as concise a Machine::Turing class as you can ...

Hrm.. interesting suggestion. The code itself would be easy. I'll hammer out something and post it in the next day or two.

I don't want to hit people with raw TM code right off the bat, because it tends to look like line noise. The logic of the program is distributed across the whole machine, and the connections aren't obvious until you know where to look. The whole point of the chapter is to teach people where to look, though, so I can introduce the class's interface one piece at a time as we walk through the heirarchy of simple machines.

I think I'm going to upgrade that to "a most interesting and excellent suggestion." Thank you very much.