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: (in-package #:quicklisp-client)
  
  (defparameter *local-projects-directory*
    (qmerge "local-projects/"))
  
  (defun system-index-file (pathname)
    (merge-pathnames "system-index.txt" pathname))
  
  (defun local-project-system-files (pathname)
    (let ((wild (merge-pathnames "**/*.asd" pathname)))
      (sort (directory wild)
            #'<
  
negative.code:                  (length (namestring file))))))
  
  (defun make-system-index (pathname)
    "Create a system index file for all system files under
  PATHNAME. Current format is one native namestring per line."
    (with-open-file (stream (system-index-file pathname)
                            :direction :output
                            :if-exists :rename-and-delete)
  