set-cdr! (set-cdr! pair obj) Stores obj in the cdr of pair. Called for its effect, like set-car!. Run(let ((p (list 1 2))) (set-cdr! p '(3 4)) p) ; => (1 3 4) (define p (list 1 2)) (set-cdr! p '(3 4)) p ; => (1 3 4)