🚀 go-pugleaf

自己フォローです．

    mad> (defmacro handle (tag value handler)
    mad>   `(block #1=#:not-thrown
    mad>      (catch ,tag
    mad>        (return-from #1# ,value))
    mad>      ,handler))

    mad> (handle 'f
    mad>   ;; value
    mad>   (+ 1 ((lambda (g) (handle 'f
    mad>                             (funcall g 1)
    mad>                             1))
    mad>         #'(lambda (y) (throw 'f y))))
    mad>   ;; handler
    mad>   1)
    mad> => 2

これ，

(defmacro handle (tag value handler)
  `(block #1=#:not-thrown
     (multiple-value-call ,handler
      (catch ,tag
       (return-from #1# ,value)))))

(handle 'f
  ;; value
  (+ 1 ((lambda (g) (handle 'f
                            (funcall g 1)
                            #'(lambda (x) x)))
        #'(lambda (y) (throw 'f y))))
  ;; handler
  #'(lambda (x) x))

とした方が感じ出てますね．

				前田敦司