anchor.diff:               (format s "~a" item))))))
   
   (defun string-to-ints (string)
  +  "Converts a string to a list of single digit ints."
   
     (log:trace "entry")
     (loop for c across string
  
positive.code:               collect line into lines
                finally (return (string-to-ints (concat-strings lines))))))
  
  (defmacro aset (array subscript value)
    `(setf (aref ,array , subscript) ,value))
  
negative.code:        finally (return (mapcar #'parse-integer ints))))
  
  (defun read-puzzle (fname)
    "Read a sudoku puzzle from disk."
  
    (log:trace "entry")
    (with-open-file (s fname :direction :input)
             (loop for line = (read-line s nil nil)
  