[CM] Resources/suggestions for learning scheme a la S7

[bil at ccrma.Stanford.EDU]

Dybvig's book is good, but s7 does not implement R6RS Scheme.
The second edition of "The Scheme Programming Language" is better
(R4RS I think).  Guile 1.8 was R5RS, if I remember right.  s7
has CL-style macros.  Since it has first class environments,
it does not need syntax-rules or any of its friends (that is,
you can write hygienic macros with define-macro).  I learned
lisp through maclisp (at SAIL), and haven't read those other books.