anchor.diff:      (probe-file stream)))
   
   (defun find-valid-system-index (pathname)
  +  "Find a valid system index file for PATHNAME; one that both exists
  +and has a newer timestamp than PATHNAME."
     (let* ((file (system-index-file pathname))
            (probed (probe-file file)))
       (when (and probed
                  (<= (directory-write-date pathname)
  -                   (directory-write-date probed)))
  +                   (file-write-date probed)))
         probed)))
   
   (defun ensure-system-index (pathname)
  +  "Find or create a system index file for PATHNAME."
     (or (find-valid-system-index pathname)
         (make-system-index pathname)))
   
   (defun find-system-in-index (system index-file)
  +  "If any system pathname in INDEX-FILE has a pathname-name matching
  +SYSTEM, return its full pathname."
     (with-open-file (stream index-file)
       (loop for namestring = (read-line stream nil)
             while namestring
  
positive.code:                  (length (namestring file))))))
  
  (defun make-system-index (pathname)
    (with-open-file (stream (system-index-file pathname)
                            :direction :output
                            :if-exists :rename-and-delete)
  
negative.code:           return (truename namestring))))
  
  (defun local-projects-searcher (system-name)
    "This function is added to ASDF:*SYSTEM-DEFINITION-SEARCH-FUNCTIONS*
  to use the local project directory and cache to find systems."
    (when (probe-directory *local-projects-directory*)
      (let ((system-index (ensure-system-index *local-projects-directory*)))
        (when system-index
  