automata.scm

   1 (use-modules (srfi srfi-9)
   2              (srfi srfi-1))
   3
   4 (define (next-token stream)
   5   (if (pair? stream)
   6       (car stream)))
   7
   8 (define (transition machine state)
   9   ((cdr (assoc state (cdr machine)))
  10    (cons (if (pair? (car machine)) (cdr (car machine)))
  11          (cdr machine))
  12    (next-token (car machine))))
  13
  14 (define (run-machine machine initial-state stream)
  15   (transition (cons stream machine) initial-state))
  16
  17 (define cadr-machine
  18   `((init . ,(lambda (m v) (case v
  19                        ((#\c) (transition m 'more))
  20                        (else #f))))
  21     (more . ,(lambda (m v) (case v
  22                        ((#\a #\d) (transition m 'more))
  23                        ((#\r) (transition m 'end))
  24                        (else #f))))
  25     (end . ,(lambda (m v) #t))))
  26
  27