(defun append (&rest lists)
(!reduce #'append-two lists '()))
- (defun reverse-aux (list acc)
- (if (null list)
- acc
- (reverse-aux (cdr list) (cons (car list) acc))))
+ (defun revappend (list1 list2)
+ (while list1
+ (push (car list1) list2)
+ (setq list1 (cdr list1)))
+ list2)
(defun reverse (list)
- (reverse-aux list '()))
+ (revappend list '()))
(defun list-length (list)
(let ((l 0))
(defun listp (x)
(or (consp x) (null x)))
+ (defun nthcdr (n list)
+ (while (and (plusp n) list)
+ (setq n (1- n))
+ (setq list (cdr list)))
+ list)
+
(defun nth (n list)
- (cond
- ((null list) list)
- ((zerop n) (car list))
- (t (nth (1- n) (cdr list)))))
+ (car (nthcdr n list)))
(defun last (x)
- (if (consp (cdr x))
- (last (cdr x))
- x))
+ (while (consp (cdr x))
+ (setq x (cdr x)))
+ x)
(defun butlast (x)
(and (consp (cdr x))
(cons (car x) (butlast (cdr x)))))
(defun member (x list)
- (cond
- ((null list)
- nil)
- ((eql x (car list))
- list)
- (t
- (member x (cdr list)))))
+ (while list
+ (when (eql x (car list))
+ (return list))
+ (setq list (cdr list))))
(defun remove (x list)
(cond