transcendental-lisp/lisp/dlambda.lisp

(defun mapcar (fn ls)
  (if (null ls)
    ()
    (cons
      (funcall fn (first ls))
      (mapcar fn (rest ls))
    )
  )
)

(define-macro dlambda (&rest methods)
  (cons
    (quote lambda)
    (cons
      (quote (&rest arguments))
      (list
        (cons
          (quote case)
          (cons
            (quote (first arguments))
            (mapcar
              (lambda (method)
                (cons
                  (first method)
                  (list
                    (cons
                      (quote apply)
                      (cons
                        (cons
                          (quote lambda)
                          (rest method)
                        )
                        (list
                          (if (equal t (car method))
                            (quote arguments)
                            (quote (rest arguments))
                          )
                        )
                      )
                    )
                  )
                )
              )
              methods
            )
          )
        )
      )
    )
  )
)