I remember code in the physical book being in scheme..

..perhaps just this section:

  Computation
  -----------

   STUTTER - a simple lisp interpreter that only understands car, cdr,
   cons, if, set, equal, quote, and lambda, but is still Turing-complete.
   Uses stop-and-copy garbage collection and has an adjustable heap size.
   Examples that implement integer and floating-point arithmetic are
   provided.  There is even an example STUTTER function to compute the
   square root of a floating-point argument with nothing but the primitives
   listed above.