Write a program in your favorite imperative language that has the same input and output as the Scheme program of Figure 11.1. Can you make any general observations about the usefulness of Scheme for symbolic computation, based on your experience?

Figure 11.1

(define simulate (lambda (dfa input) (letrec ((helper ; note that helper is tail recursive, ; but builds the list of moves in reverse order (lambda (moves d2 i) (let ((c (current-state d2))) (if (null? i) (cons c moves) (helper (cons c moves) (move d2 (car i)) (cdr i))))))) (let ((moves (helper '() dfa input))) (reverse (cons (if (is-final? (car moves) dfa) 'accept 'reject) moves)))))) ;; access functions for machine description: (define current-state car) (define transition-function cadr) (define final-states caddr) (define is-final? (lambda (s dfa) (mem s (final-states dfa)))) (define move (lambda (dfa symbol) (let ((cs (current-state dfa)) (trans (transition-function dfa))) (list (if (eq? cs 'error) 'error (let ((pair (assoc (list cs symbol) trans))) (if pair (cadr pair) 'error))); new start state trans ; same transition function (final-states dfa))))) same final states