Function: BEFORE

Documentation

tests if x comes before y in the specified list

Source

(defun before (x y lst &key (test #'eql))
  "tests if x comes before y in the specified list"
  (and lst
       (let ((first (car lst)))
	 (cond ((funcall test y first) nil)
	       ((funcall test x first) lst)
	       (t (before x y (cdr lst) :test test))))))