[plt-scheme] Wrote some notes on using PLT Scheme for TAPL stuff

Hi everyone,

I've been reading Pierce's excellent "Types and Programming Languages"
textbook, and thought it might be fun to try to use PLT Scheme instead of
OCaml.  It's also motivating me to learn the parser-tools collection.
I've written some notes I hope folks find useful.  So far, the notes show
introductory usage of plt-match.ss, structures, and the parser-tools to
implement the baby interpreter in Chapter Four.

I'll temporarily placing them here as I work through the book:

    http://hkn.eecs.berkeley.edu/~dyoo/tmp/tapl-plt.txt

and I'll try to relocate the URL to somewhere more permanent once I flesh
the notes out. Comments, corrections, and criticisms would be greatly
appreciated.  Thanks!