gistfile1.lisp

(defun remove-all (elts list &key (key #'identity) (test #'eql))
  "Removes all elements of ELTS from LIST. This is similar to set-difference with the exception
that the order of the elements in  LIST is preserved."
  (remove-if #'(lambda (elt) (member (funcall key elt) elts :test test)) list))
  
(defun all-same-order-p (list-of-lists &key (test #'eql))
  "Returns true if the lists in LIST-OF-LISTS are all in the same order."
  (flet ((same-order-p (list1 list2)
           (let ((diff (set-exclusive-or list1 list2 :test test)))
             (equal (remove-all diff list1 :test test)
                    (remove-all diff list2 :test test)))))
    (loop for (first . rest) on list-of-lists
          :always (loop for other in rest
                        :always (same-order-p first other)))))