Interpretador do LISP de John McCarthy em Common Lisp. Tem como operadores primitivos quote, atom, eq, car, cdr, cons e cond.

(defun not. (x)
  (cond (x '())
        ('t 't)))

(defun null. (x)
  (eq x '()))

(defun and. (x y)
  (cond (x (cond (y't) ('t '())))
        ('t '())))

(defun pair. (x y)
  (cond ((and. (null. x) (null. y)) '())
        ((and. (not. (atom x)) (not. (atom y)))
         (cons (list (car x) (car y))
               (pair. (cdr x) (cdr y))))))

(defun append. (x y)
  (cond ((null. x) y)
        ('t (cons (car x) (append. (cdr x) y)))))

(defun assoc. (x y)
  (cond ((eq (caar y) x) (cadar y))
        ('t (assoc. x (cdr y)))))

(defun eval. (e a)
  (cond
    ((atom e) (assoc. e a))
    ((atom (car e))
     (cond
       ((eq (car e) 'quote) (cadr e))
       ((eq (car e) 'atom)  (atom   (eval. (cadr e) a)))
       ((eq (car e) 'eq)    (eq     (eval. (cadr e) a)
                                    (eval. (caddr e) a)))
       ((eq (car e) 'car)   (car    (eval. (cadr e) a)))
       ((eq (car e) 'cdr)   (cdr    (eval. (cadr e) a)))
       ((eq (car e) 'cons)  (cons   (eval. (cadr e) a)
                                    (eval. (caddr e) a)))
       ((eq (car e) 'cond)  (evcon. (cdr e) a))
       ('t (eval. (cons (assoc. (car e) a)
                         (cdr e))
                  a))))
   ((eq (caar e) 'label)
    (eval. (cons (caddar e) (cdr e))
           (cons (list (cadar e) (car e)) a)))
   ((eq (caar e) 'lambda)
    (eval. (caddar e)
           (append. (pair. (cadar e) (evlis. (cdr e) a))
                    a)))))

(defun evcon. (c a)
  (cond ((eval. (caar c) a)
         (eval. (cadar c) a))
        ('t (evcon. (cdr c) a))))

(defun evlis. (m a)
  (cond ((null. m) '())
        ('t (cons (eval. (car m) a)
            (evlis. (cdr m) a)))))

(defun apply. (f a)
  (eval. (cons f (appq. a)) '()))


(defun appq. (m)
  (cond ((null m) '())
        (t
         (cons (list 'quote (car m)) (appq. (cdr m))))))

As referências são:

Created: NaN

Last updated: 23-01-2025 [00:04]


For attribution, please cite this page as:

Charters, T., "Lisp de John McCarthy em CL": https://nexp.pt/jmc-lisp.html (23-01-2025 [00:04])


(cc-by-sa) Tiago Charters - tiagocharters@nexp.pt