(module kmp
   (main main)
   (import kmp-table))

(define (main args)
   (print (kmp:KMP (cadr args) (caddr args))))

(define (kmp:KMP Word Text)
   (let ((Tpref (kmp:table Word))
         (Ltext (string-length Text))
         (LastCharPos (- (string-length Word) 1)))
      (let loop ((i 0)
                 (j 0))
         (cond ((>= (+ i j) Ltext)
                -1)
               ((char=? (string-ref Text (+ i j))
                        (string-ref Word j))
                (if (= j LastCharPos)
                    i
                    (loop i (+ j 1))))
               (else
                (loop
                 (- (+ i j) (vector-ref Tpref j))
                 (if (> j 0)
                     (vector-ref Tpref j)
                     j))) ) ) ))