• last list &optional n → tail

• list - a list, which might be a dotted list but must not be a circular list.
• n - a non-negative integer. The default is 1.
• tail - an object.

last returns the last n conses (not the last n elements) of list). If list is nil, last returns nil.

If n is zero, the atom that terminates list is returned. If n is greater than or equal to the number of cons cells in list, the result is list.

(last nil) 

→

NIL



(last '(1 2 3)) 

→

(3)



(last '(1 2 . 3)) 

→

(2 . 3)



(defparameter *x* (list 'a 'b 'c 'd)) 

→

*X*



(last *x*) 

→

(D)



(rplacd (last *x*) (list 'e 'f)) 

→

(D E F)



*x* 

→

(A B C D E F)



(last *x*) 

→

(F)



(last '(a b c)) 

→

(C)



(last '(a b c) 0) 

→

NIL



(last '(a b c) 1) 

→

(C)



(last '(a b c) 2) 

→

(B C)



(last '(a b c) 3) 

→

(A B C)



(last '(a b c) 4) 

→

(A B C)



(last '(a . b) 0) 

→

B



(last '(a . b) 1) 

→

(A . B)



(last '(a . b) 2) 

→

(A . B)

None.

None.

The consequences are undefined if list is a circular list.

Should signal an error of type type-error if n is not a non-negative integer.

Function BUTLAST, Function NTH

The following code could be used to define last.

(defun last (list &optional (n 1))
  (check-type n (integer 0))
  (do ((l list (cdr l))
       (r list)
       (i 0 (1+ i)))
      ((atom l) r)
    (if (>= i n) (pop r))))

None.

\issue{LAST-N} \issue{DOTTED-LIST-ARGUMENTS:CLARIFY}