How to expand a macro in MIT Scheme

Question

I have written a simple macro:

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

Usage example: (myif #t "yes" "no").

In MIT Scheme, how do I show the macro expansion of the example above? Is there something similar to Common Lisp's macroexpand and macroexpand-1 or Racket's expand and expand-once?

(MIT Scheme version: 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)))))

will print the Scode. This is enough for debugging.

As it's expressed in the warning of compilation, it is important not to activate the optimizations, otherwise you won't see any more the literal translation into Scode.

This is the starting point when I debug (not only macros).