Returns the number of directory levels in pathname
The pathname must end in a filename. Further, this function assumes that directories in a pathname are separated by forward slashes ("/").
(define (directory-depth pathname)
;; Count the directory depth of a path name
(let loop ((count 0) (pathlist (match-split pathname "/")))
(if (null? pathlist)
(- count 1) ;; pathname should always end in a filename
(if (or (equal? (car pathlist) "/") (equal? (car pathlist) "."))
(loop count (cdr pathlist))
(if (equal? (car pathlist) "..")
(loop (- count 1) (cdr pathlist))
(loop (+ count 1) (cdr pathlist)))))))