null之间的区别？空的？在Scheme中

Berkeley's "CS 61A Lecture 8: UI Recursion and Iteration III" says that null? checks if the list is empty and empty? checks if the list is empty or the word is empty? The lecturer also goes on to say (null? empty) will return false. But DrScheme doesnt mind at all.Berkeley's "CS 61A Lecture 8: UI Recursion and