talk about loop abuse:

     (flet ((make-random-move (rankf)
                     (loop for place in places
                           for rank = (funcall rankf place)
                           collect (cons place rank) into ranks
                           sum rank into ranks-total
                           finally (loop with r = (if (zerop ranks-total) -1
                                                    (random ranks-total))
                                         for (place . rank) in (shuffle ranks)
                                         sum rank into current-ranks-total
                                         when (< r current-ranks-total)
                                         do (cond ((and (eq place ahead) (move ant)))
                                                  ((eq place ahead-left)
                                                   (turn ant -1))
                                                  ((eq place ahead-right)
                                                   (turn ant +1)))))))
              (if (ant-food ant)