CS 342 Lecture -*- Outline -*-

* Interpreter for Scheme

	advert: more elegant than others so far, fewer special cases
		 compare with LISP (only a few lines longer, more power)

** environments
	most important change
		environment frame (stack frame)
		environment is list of environment frames (static scoping)
	look at searching (p. 113)
	extension (p. 114) used for evaluation of closures
		binds formals to actuals

	exercise: can you redefine + in Scheme?

** closures
	p. 111, clause in SEXPREC