Scheme programs from the Wizard Book.
Use $ gsi file.scm or $ guile file.scm.
- normal-order evaluation = fully-expand and then reduce
- applicative-order evaluation = evaluate the arguments and then apply; more efficient
- math: usually declarative descriptions (what is); computer science: imperative descriptions (how to)
- a formal parameter is a bound variable; if not bound, it's a free variable. You can rename bound variables in a procedure without changing its meaning, but free variables matter.
- definitions can be nested = block structure
- a tail-recursive implementation (IEEE mandates that Scheme implementations be tail-recursive) means that it will execute an iterative process in constant space even if it's written as a recursive procedure (see iterative factorial in
alg.scm) -- just ajmpinstead of creating new call frames.