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From: Douglas Lewan <d.lewan2000@gmail.com>
To: Stefan Monnier <monnier@iro.umontreal.ca>,
	help-gnu-emacs <help-gnu-emacs@gnu.org>
Subject: Re: Compiling a recursive macro
Date: Thu, 11 Jun 2020 17:23:27 -0400	[thread overview]
Message-ID: <f7a5b1e1-8001-894d-9fca-fc624b344b6b@gmail.com> (raw)
In-Reply-To: <jwvtuzh8gtj.fsf-monnier+emacs@gnu.org>

On 6/11/20 4:57 PM, Stefan Monnier wrote:
>> That suggests to me that you can't compile any recursive macro.
> Depends what you mean by "recursive macro".
> What this prevents is to use a macro inside the definition of a macro.
>
> Most cases of "recursive macros" instead just returns code which
> itself uses that macro.  In that case, there's no real recursion: the
> macro just returns a list which happens to include a symbol which has
> the same name as the macro.  And then the macro-expander will end up
> calling that macro back when it gets to macro-expanding that chunk
> of code.
> This works just fine (and may inf-loop, of course).

It did work when not compiled. However, when compiling I got a 
max-depth-exceeded error. (Forgive the paraphrasing, I'm now running a 
new instance of emacs.

And, if anyone cares, I did find a work-around for the macro in 
question. It had the following structure:

(defmacro mmm ()
     (cond ((at-root-p)
            do  tree-wide stuff)
           (t
            (with-current-buffer root (mmm)))

Since there is never more than one level of recursion, I defined another 
macro to do the tree-wide stuff first and then call that from mmm.


-- 
,Doug
d.lewan2000@gmail.com
(908) 720 7908

If this is what winning looks like, I'd hate to see what losing is.



  reply	other threads:[~2020-06-11 21:23 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-11 20:15 Compiling a recursive macro Douglas Lewan
2020-06-11 20:57 ` Stefan Monnier
2020-06-11 21:23   ` Douglas Lewan [this message]
2020-06-11 21:32     ` Michael Heerdegen
2020-06-11 21:38       ` Douglas Lewan
2020-06-11 21:55         ` Michael Heerdegen
2020-06-11 22:21           ` Douglas Lewan
2020-06-12 10:49             ` Michael Heerdegen
2020-06-12 16:11               ` Douglas Lewan
2020-06-12  2:10           ` Douglas Lewan
2020-06-13  9:49             ` Michael Heerdegen
2020-06-13 13:34               ` Jakub Jankiewicz
2020-06-11 22:02     ` Stefan Monnier
2020-06-11 21:27   ` Michael Heerdegen
2020-06-12  0:03 ` Jakub Jankiewicz

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