This adds many comments to the final interpreter, which hopefully helps
me (and anyone else reading this) understand what's going on inside the
3G interpreter.
[refactor] This last interpreter takes all the evaluate function's
"syntax" objects and moves them into a lookup table. THis prefigures the
idea of making even the syntax malleable and extensible by future code.
I have to wonder if there's a place for making some core commands (the
"holy 7" of McCarthy, for example) un-reassignable.
Probably not. I can vaguely see an interest in wrapping even some core
functions (car, cdr, cons) in contractual decorators.
This concludes the base homework for chapter 3. I might get to the
exercises someday.
Elf M. Sternberg