[Sussman] THE SUSSMAN II: CDR VENGEANCE [MIT]

Holy shit, I knew the Sussman wouldn't stay there with his arms crossed after they shut down 6.001. Looks like he ditched the Anti-Cudder and went ahead with this:

http://swiss.csail.mit.edu/classes/symbolic/spring08/

Students should have significant programming experience in Scheme or
Common Lisp.
Could this ultimately result in a book BETTER THAN SICP‽

(define (unify t1 t2)
  (let lp ((xs (list t1))
           (ys (list t2)) (dict '()))
    (cond ((and (null? xs) (null? ys)) dict)
...

What value could you give to LIST to make (NULL? (LIST value)) evaluate to #t?

According to R5RS:

  ``library procedure:  (null? obj)
    Returns #t if obj is the empty list, otherwise returns #f.''

So how could (NULL? (LIST anything)) ever evaluate to #t?

Has the Sussman made a mistake?