(require 'stdlib)

;; (multiple-value-bind (SYM SYM...) FORM BODY): collect multiple
;; return values.  FORM must return a list; the BODY is then executed
;; with the first N elements of this list bound (`let'-style) to each
;; of the symbols SYM in turn.  This is analogous to the Common Lisp
;; `multiple-value-bind' macro, using lists to simulate true multiple
;; return values.  For compatibility, (values A B C) is a synonym for
;; (list A B C).

;; scheme calls this: receive

(defmacro multiple-value-bind (vars form #!rest body)
  (let ((temp (gensym)) (n -1))
    (list* 'let* (cons (list temp form)
                       (mapcar (lambda (v)
                                   (list v (list 'nth (setq n (1+ n)) temp)))
                               vars))
           body)))

(define values list)

(define (env x)
  (values (1- x) x (1+ x)))

(multiple-value-bind (a b c) (env 4)
  (print (list 'a= a 'b= b 'c= c)))