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Lisp source code rewriting system

I would like to take the Emacs Lisp code, which was extended by a macro, and unmacro extends it. I requested this on the Emacs forum without success. See: https://emacs.stackexchange.com/questions/35913/program-rewriting-systems-unexpanded-a-defmacro-given-a-list-of-macros-to-undo

However, one would think that such a conversion of S-expressions is similar to up Lisp alley. And defmacro, I believe, is available in Lisp, as in Emacs Lisp.

So, of course, there are program conversion systems or term rewrite systems that can be adapted here.

Ideally, in certain situations, such a tool could work directly with defmacroto search for and replace its template. However, even if I need to come up with a specific search and replace the templates manually to add transformations to the system, the presence of such a structure for work would still be useful

Summary of the results so far: Although there have been a few answers that explore interesting possibilities, there is nothing final right now. Therefore, I believe that it is better to leave it open. I will summarize some suggestions. (I supported all the answers, which were actually answers, not a comment about complexity.)

Firstly, many people believe that a special form of macro only makes an extension, or, as Drew put it:

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:

(defmacro my-macro-1 ()
  `1)

(defmacro my-macro-2 ()
  `(my-function (my-macro-1)))

(defun my-function (n)
  (* n 100))

(macrolet ((my-macro-1 ()
             `2))
  (flet ((my-function (n)
           (* n 1000)))
    (my-macro-2)))

(my-function (my-macro-2)), (my-function 2). 2000.

- :

(defmacro my-macro-2 ()
  ;; capture global bindings of my-macro-1 and my-function-1 by name
  (flet ((my-macro-1-global (form env)
           (funcall (macro-function 'my-macro-1) form env))
         (my-function-global (&rest args)
           ;; hope the compiler can optimize this
           (apply 'my-function args)))
    ;; store them globally in uninterned symbols
    ;; hopefully, no one will mess with them
    (let ((my-macro-1-symbol (gensym (symbol-name 'my-macro-1)))
          (my-function-symbol (gensym (symbol-name 'my-function))))
      (setf (macro-function my-macro-1-symbol) #'my-macro-1-global)
      (setf (symbol-function my-function-symbol) #'my-function-global)
      `(,my-function-symbol (,my-macro-1-symbol)))))

100.

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Here is a simple example that I might think:

Regarding the definition when:

(defmacro when (cond &rest body)
  (list 'if cond (cons 'progn body)))

We can transform the code using a template pcase, for example:

(let ((form '(if (and foo bar baz) (progn do (all the) things))))
  (pcase form
    (`(if ,cond (progn . ,body))
     `(when ,cond ,@body))
    (_ form)))

=> (when (and foo bar baz) do (all the) things)

Obviously, if macro definitions change, then your templates will stop working (but this is a pretty safe kind of failure).

Caution: this is the first time I wrote a form pcaseand I don’t know what I don’t know. It seems to be working as intended.

+1
source

Source: https://habr.com/ru/post/1688837/

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