(define (foldl proc init lst)
  (let loop ((lst lst) (r init))
    (if (null? lst) 
        r
        (loop (cdr lst) (proc r (car lst))))))

(define (numeric-value str)
  (let ((l (string->list str))
        (t '((#\C 100) (#\D 500) (#\I 1) (#\L 50) (#\M 1000)            
             (#\U 5) (#\V 5))))
     (foldl (lambda (s x) 
              (let ((r (assoc x t)))
                (if r 
                    (+ (cadr r) s)
                    s)))
              0
              (map char-upcase l))))

(define (go)
   (display (numeric-value "vicarius filii dei"))
   (newline)
   0))
(go)