使えるマクロ: シェル引数を変数にバインド

こういうのこそマクロの使い道。

(defmacro with-boolean-options (bindings before after &body body)
  (assert (typep before 'symbol))
  (assert (typep after 'symbol))
  `(let ((,after ,before))
     (let ,(mapcar
            (lambda (bind)
              (ematch bind
                ((list (and var (type symbol))
                       (and str (type string)))
                 `(,var
                   (prog1
                     (if (member ,str ,after :test #'string=) t nil)
                     (setf ,after (remove ,str ,after :test #'string=)))))))
            bindings)
       ,@body)))


(defun main ()
  (print sb-ext:*posix-argv*)
  (match sb-ext:*posix-argv*
    ((list* _ rest)
     (with-boolean-options ((*invert* "--invert")
                            (*ignore-first* "--ignore-first")
                            (*block* "--block")) rest rest
       (apply #'output-to-csv rest)))))

;;;; 展開結果
(LET ((REST REST))
  (LET ((*INVERT*
         (PROG1
             (IF (MEMBER "--invert" REST :TEST #'STRING=)
                 T
                 NIL)
           (SETF REST (REMOVE "--invert" REST :TEST #'STRING=))))
        (*IGNORE-FIRST*
         (PROG1
             (IF (MEMBER "--ignore-first" REST :TEST #'STRING=)
                 T
                 NIL)
           (SETF REST (REMOVE "--ignore-first" REST :TEST #'STRING=))))
        (*BLOCK*
         (PROG1
             (IF (MEMBER "--block" REST :TEST #'STRING=)
                 T
                 NIL)
           (SETF REST (REMOVE "--block" REST :TEST #'STRING=)))))
    (APPLY #'OUTPUT-TO-CSV REST)))