(defun nth (n list)
(car (nthcdr n list)))
+(define-setf-expander nth (n list)
+ (let ((g!list (gensym))
+ (g!index (gensym))
+ (g!value (gensym)))
+ (values (list g!list g!index)
+ (list list n)
+ (list g!value)
+ `(rplaca (nthcdr ,g!index ,g!list) ,g!value)
+ `(nth ,g!index ,g!list))))
+
(defun caar (x) (car (car x)))
(defun cadr (x) (car (cdr x)))
(defun cdar (x) (cdr (car x)))
(rplaca tail (cdar tail)))
(collect (apply func elems))))))))
+(defun mapn (func list)
+ (with-collect
+ (while list
+ (collect (funcall func list))
+ (setq list (cdr list)))))
+
+(defun maplist (func list &rest lists)
+ (let ((lists (cons list lists)))
+ (with-collect
+ (block loop
+ (loop
+ (let ((elems (mapn #'car lists)))
+ (do ((tail lists (cdr tail)))
+ ((null tail))
+ (when (null (car tail)) (return-from loop))
+ (rplaca tail (cdar tail)))
+ (collect (apply func elems))))))))
+
(defun mapc (func &rest lists)
(do* ((elems (map1 #'car lists) (map1 #'car lists-rest))
(lists-rest (map1 #'cdr lists) (map1 #'cdr lists-rest)))
(list x)
(list new-value)
`(progn (rplacd ,cons ,new-value) ,new-value)
- `(car ,cons))))
+ `(cdr ,cons))))
;; The NCONC function is based on the SBCL's one.
(defun intersection (list1 list2 &key (test #'eql) (key #'identity))
(let ((new-list ()))
(dolist (x list1)
- (when (member x list2 :test test :key key)
+ (when (member (funcall key x) list2 :test test :key key)
(push x new-list)))
new-list))