GNU bug report logs - #27177
26.0.50: Macroexpanding cl-loop and friends (make-symbol usage)

Previous Next

Full log

Message #23 received at 27177 <at> debbugs.gnu.org (full text, mbox):

From: Alex <agrambot <at> gmail.com>
To: Michael Heerdegen <michael_heerdegen <at> web.de>
Cc: 27177 <at> debbugs.gnu.org, npostavs <at> users.sourceforge.net
Subject: Re: bug#27177: 26.0.50: Macroexpanding cl-loop and friends
 (make-symbol usage)
Date: Wed, 31 May 2017 20:02:30 -0600

Michael Heerdegen <michael_heerdegen <at> web.de> writes:

> With print-circle and print-gensym bound, I think the result does not
> really read worse than how it would look like with with `cl-gensym'
> generated code.

That's much better, though I still think it could/should be better. For
example, if you have multiple uninterned symbols with different
symbol-names, they're all referenced by #number, and use the same
counter.

It also seems to make the output uglier as well. Consider:

(macroexpand '(cl-loop for x in '(1 2 3)
                       for y in '(a b c)
                       repeat 10
                       repeat 20
                       collect (list x y)))

Note the expressions using #5#. I suppose the 0 is being shared.

It would also be nice if instead of many --cl-var-- variables,
particular clauses would result in different symbol-names. For instance,
if the `repeat' clause made a symbol called --cl-repeat--. This would
further help readability.

Also, using gensym could help 3rd-party packages. I usually use
macrostep to expand macros and the value of print-circle has no effect
on its expansions. macrostep individually prints out each uninterned
symbol using prin1; can this approach be easily modified to get the same
result as macroexpand?

PS: The first line of the documentation of print-circle only mentions
that it affects recursive structures. Perhaps it should mention the
"shared substructures" part in the first line for emphasis?

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.