;; A word generator designed for use in an interactive environment

(define (fold-right f init seq)
  (if (null? seq)
      init
      (f (car seq)
         (fold-right f init (cdr seq)))))

(define (pick-random lst)
  (let ((index (random (length lst))))
    (list-ref lst index)))

(define (C)
  (pick-random '("s" "v" "ch" "j")))

(define (V)
  (pick-random '("a" "e" "u")))

(define (N)
  (pick-random '("n" "l")))

(define (string->procs str)
  (define (randomize chars)
    (cond ((null? chars) '())
          ((char=? (car chars) #\?)
           (if (zero? (random 2))
               (cons (cadr chars) (randomize (cddr chars)))
               (randomize (cddr chars))))
          (else (cons (car chars) (randomize (cdr chars))))))
  (map (lambda (c) (eval (string->symbol (string c))))
       (randomize (string->list str))))

(define (generate-word template)
  (apply string-append
         (map (lambda (f) (f))
              (string->procs template))))

;; Example: (generate-word "CVNVN")
;; => "jenel"