Exercise 5.48: The compile-and-go
interface implemented in this section is awkward, since the compiler can be
called only once (when the evaluator machine is started).  Augment the
compiler-interpreter interface by providing a compile-and-run primitive
that can be called from within the explicit-control evaluator as follows:


;;; EC-Eval input:
(compile-and-run
 '(define (factorial n)
    (if (= n 1)
        1
        (* (factorial (- n 1)) n))))

;;; EC-Eval value:
ok

;;; EC-Eval input:
(factorial 5)

;;; EC-Eval value:
120