Исправление saufesma, (текущая версия) :
Тут такое дело, мне с Lispworks support обзор наших с тобой кодов пришел, не лестный
I think the style used in your sum-list and labels-sum-list examples is not good because it mixes side-effects (i.e. setq) with recursion for no good reason. The cleaner, standard way to do this is to add on return from the recursive step:
(defun sum-list-1 (lst)
(if (eq (car lst) nil)
0
(+ (car lst) (sum-list-1 (cdr lst)))))
or pass the sum as an extra argument:
(defun sum-list-2 (lst &optional (n 0))
(if (eq (car lst) nil)
n
(sum-list-2 (cdr lst) (+ (car lst) n))))
а это наша версия
(defvar *result*)
(setq *result* 0)
(defun sum-list (lst)
(if (eq (car lst) nil)
*result*
(progn
(setq *result* (+ *result* (car lst)))
(sum-list (cdr lst)))))
(sum-list '(1 2 3 4 5)) => 15
;; I rewrite the above code using labels.
(defun labels-sum-list (lst &optional (n 0))
(labels ((temp (lst)
(if (null (car lst))
n
(progn
(setq n (+ n (car lst)))
(temp (cdr lst))))))
(temp lst)))
Вот видишь век живи век учись, я вот так переписал
(defun labels-sum-list (lst &optional (n 0))
(labels ((temp (lst n)
(if (null (car lst))
n
(progn
(temp (cdr lst) (+ n (car lst)))))))
(temp lst n)))
(labels-sum-list '(1 2 3 4 5) 0)
Исходная версия saufesma, :
Тут такое дело, мне с Lispworks support обзор наших с тобой кодов пришел, не лестный
I think the style used in your sum-list and labels-sum-list examples is not good because it mixes side-effects (i.e. setq) with recursion for no good reason. The cleaner, standard way to do this is to add on return from the recursive step:
(defun sum-list-1 (lst)
(if (eq (car lst) nil)
0
(+ (car lst) (sum-list-1 (cdr lst)))))
or pass the sum as an extra argument:
(defun sum-list-2 (lst &optional (n 0))
(if (eq (car lst) nil)
n
(sum-list-2 (cdr lst) (+ (car lst) n))))
а это наша версия
(defvar *result*)
(setq *result* 0)
(defun sum-list (lst)
(if (eq (car lst) nil)
*result*
(progn
(setq *result* (+ *result* (car lst)))
(sum-list (cdr lst)))))
(sum-list '(1 2 3 4 5)) => 15
;; I rewrite the above code using labels.
(defun labels-sum-list (lst &optional (n 0))
(labels ((temp (lst)
(if (null (car lst))
n
(progn
(setq n (+ n (car lst)))
(temp (cdr lst))))))
(temp lst)))