Sorry, I should have written a longer message, with most, or all,
parts of it written in the first person...

In my experience hanging out at the #emacs channel at Freenode and
asking for help or hints on elisp is fun, and it's easy to test ideas
interactively with C-x C-e... asking for help on the C side of Emacs
is not so fun - patching the C source is considered arcane knowledge
(<- my impression!) and fewer people will be able to discuss that and
to help... also, I don't know how to recompile Emacs after a change in
a .c and restart it in less that 30 seconds (slow machine here - I use
an old ThinkPad with LibreBoot) - in fact I don't think I've ever
patched the C source before! Here's the script that I used to test
Arthur's patch:

  # Download the attachments of this message:
  #   https://lists.gnu.org/archive/html/emacs-devel/2019-12/msg00556.html
  # in /tmp/:
  cd /tmp/
  wget -O bytecomp.patch
https://lists.gnu.org/archive/html/emacs-devel/2019-12/txtkIKP0OSag7.txt
  wget -O lread.patch
https://lists.gnu.org/archive/html/emacs-devel/2019-12/txttFA8rLAthl.txt
  wget -O chatty.el
https://lists.gnu.org/archive/html/emacs-devel/2019-12/txt6f3pEXMWNI.txt

  # Apply the patches in /tmp/:
  cd /tmp/
  cp -v ~/bigsrc/emacs/src/lread.c                 /tmp/
  cp -v ~/bigsrc/emacs/lisp/emacs-lisp/bytecomp.el /tmp/
  # (find-man "1 patch")
  patch lread.c     lread.patch
  patch bytecomp.el bytecomp.patch

  # If they applied cleanly, copy the patched files back:
  cp -v /tmp/lread.c     ~/bigsrc/emacs/src/lread.c
  cp -v /tmp/bytecomp.el ~/bigsrc/emacs/lisp/emacs-lisp/bytecomp.el

  # Rebuild Emacs.
  # I usually skip some of the steps below - my way of executing
  # these scripts line by line from Emacs is explained here:
  #   http://angg.twu.net/emacsconf2019.html
  #   http://angg.twu.net/eev-intros/find-eev-quick-intro.html#6

  rm -Rfv  ~/bigsrc/emacs/
  mkdir -p ~/bigsrc/emacs/
  cd       ~/bigsrc/
  git clone git://git.sv.gnu.org/emacs

  cd       ~/bigsrc/emacs/
  time ./autogen.sh   2>&1 | tee oa
  time ./configure    2>&1 | tee oc
  time make bootstrap 2>&1 | tee omb
  time make           2>&1 | tee om

  # Run the new Emacs:
  ~/bigsrc/emacs/src/emacs


Cheers,
  Eduardo Ochs
  http://angg.twu.net/#eev


On Fri, 20 Dec 2019 at 22:18, arthur miller <arthur.miller@live.com> wrote:

> > I was expecting that Arthur would come up with a preprocessor written
> > in (I guess) 30 lines of Elisp...
>
> Interesting 🙂. If you have red my previous mails to this list you
> might have noticed that I am not an elisp guru. Stefan has
> outlined two possible ways how this could be implemented in
> Elisp, if you follow his advice I am sure you will have a working
> solution you can present to us. I don't care how many lines of code
> it will take.
>
> (...)
>