如何在麻省理工学院方案中扩展宏

Question

我写了一个简单的宏：

(define-syntax myif
  (syntax-rules ()
    ((_ condition a b)
     (if condition a b))))

用法示例：（myif＃t“ yes”“否”）。

在MIT方案中，如何显示上述示例的宏扩展？是否有类似于Common Lisp的Macroexpand和Macroexpand-1或球拍的展开和Expand-once-once？

（麻省理工学院方案版本：11.2）

Answer 1

% cat macro.scm 

(define-syntax myif
  (syntax-rules ()
    ((_ condition a b)
     (if condition a b))))


% mit-scheme --silent
(sf "macro.scm")

;Generating SCode for file: "macro.scm" => "macro.bin"...
;  This program does not have a USUAL-INTEGRATIONS declaration.
;  Without this declaration, the compiler will be unable to perform
;  many optimizations, and as a result the compiled program will be
;  slower and perhaps larger than it could be.  Please read the MIT
;  Scheme User's Guide for more information about USUAL-INTEGRATIONS.
;... done
(pp (fasload "macro.bin"))
;Loading "macro.bin"... done
(define-syntax myif
  (er-macro-transformer
   (lambda (form rename compare)
     (if (and (pair? form)
              (let ((temp (cdr form)))
                (and (pair? temp)
                     (let ((temp (cdr temp)))
                       (and (pair? temp)
                            (let ((temp (cdr temp)))
                              (and (pair? temp)
                                   (null? (cdr temp)))))))))
         (list (rename 'if)
               (car (cdr form))
               (car (cdr (cdr form)))
               (car (cdr (cdr (cdr form)))))
         (ill-formed-syntax form)))))

将打印SCODE。这足以调试。

正如它在汇编警告中所表达的那样，重要的是不要激活优化，否则您将不会再将其字面翻译成SCODE。

这是我调试（不仅宏）的起点。