Function: IS-IN-HEAP

Source

(defun is-in-heap (item heap)
  (with-comparator (heap-comparator heap)
    (loop for i below (heap-size heap)
	  for elem across (heap-array heap)
	  with key-fn = (heap-key-fn heap)
	  when (comp-= (funcall key-fn elem)
		       (funcall key-fn item))
	  do (return t)
	  finally (return nil))))