GNU bug report logs - #17657
pretty-print #:width values above 49 don't work?

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Mark Polesky <markpolesky <at> yahoo.com>
To: bug-guile <at> gnu.org
Subject: pretty-print #:width values above 49 don't work?
Date: Sat, 31 May 2014 11:24:12 -0700 (PDT)

Hi,

Neither example below should be line-wrapped, but the second one 
is.  It looks like pretty-print #:width values above 49 don't
work.  Is there a workaround?


(pretty-print
  '(234 . "901234567890123456789012345678901234567")
  #:width 49) 
=>
(234 . "901234567890123456789012345678901234567")

(pretty-print
  '(234 . "9012345678901234567890123456789012345678")
  #:width 50) 
=>
(234
 .
 "9012345678901234567890123456789012345678")


$ ./config.guess
x86_64-unknown-linux-gnu

$ guile --version
Guile 1.8.8


Thanks!
- Mark

Message #8 received at 17657 <at> debbugs.gnu.org (full text, mbox):

From: Mark H Weaver <mhw <at> netris.org>
To: Mark Polesky <markpolesky <at> yahoo.com>
Cc: 17657 <at> debbugs.gnu.org
Subject: Re: bug#17657: pretty-print #:width values above 49 don't work?
Date: Sun, 01 Jun 2014 14:40:56 -0400

Mark Polesky <markpolesky <at> yahoo.com> writes:
> Neither example below should be line-wrapped, but the second one 
> is.

Our pretty printer, inherited from SLIB and originally written by Marc
Feeley, uses a great many heuristics to make formatting decisions.
These heuristics are undocumented and subject to change.

One of its heuristics is that individual expressions shall not be more
than 49 columns wide.  Notice that pretty-print.scm includes the
following internal definition:

  (define max-expr-width 50)

(although in fact the maximum width ends up being 49)

> Is there a workaround?

A couple of years ago I added an undocumented #:max-expr-width keyword
argument to pretty-print, in order to improve the formatting of
psyntax-pp.scm.  You could use that.

It would be good to redesign and rewrite our pretty-printer from scratch
at some point.

> $ guile --version
> Guile 1.8.8

We no longer support Guile 1.8.x.  You should transition to 2.0.

     Thanks,
       Mark

Message #11 received at 17657 <at> debbugs.gnu.org (full text, mbox):

From: Mark Polesky <markpolesky <at> yahoo.com>
To: Mark H Weaver <mhw <at> netris.org>
Cc: 17657 <at> debbugs.gnu.org
Subject: Re: bug#17657: pretty-print #:width values above 49 don't work?
Date: Tue, 3 Jun 2014 11:06:38 -0700 (PDT)

Mark H Weaver wrote:
> A couple of years ago I added an undocumented
> #:max-expr-width keyword argument to pretty-print, in
> order to improve the formatting of psyntax-pp.scm.  You 
> could use that.

Nice, but why leave it undocumented?  That's useful!
Anyway, I can't use it yet: my project still depends on
1.8.8, and I see that you added it in 2.0.6.

> We no longer support Guile 1.8.x.  You should transition
> to 2.0.

We are well aware, but the developers who are working on it
keep mentioning problems with curried definitions, saying
things like "stabbing around in the dark around bugs and 
undocumented areas", and that the stable version doesn't
seem so stable...  In any case, the task of transitioning to
2.0 is beyond my own expertise, so I'll just see how it
plays out.

But thank you for your explanation, advice, and quick
response.

- Mark

Message #16 received at 17657-done <at> debbugs.gnu.org (full text, mbox):

From: Andy Wingo <wingo <at> pobox.com>
To: Mark H Weaver <mhw <at> netris.org>
Cc: Mark Polesky <markpolesky <at> yahoo.com>, 17657-done <at> debbugs.gnu.org
Subject: Re: bug#17657: pretty-print #:width values above 49 don't work?
Date: Tue, 21 Jun 2016 16:47:20 +0200

Hi :)

On Sun 01 Jun 2014 20:40, Mark H Weaver <mhw <at> netris.org> writes:

> Mark Polesky <markpolesky <at> yahoo.com> writes:
>> Neither example below should be line-wrapped, but the second one 
>> is.
>
> Our pretty printer, inherited from SLIB and originally written by Marc
> Feeley, uses a great many heuristics to make formatting decisions.
> These heuristics are undocumented and subject to change.
>
> One of its heuristics is that individual expressions shall not be more
> than 49 columns wide.  Notice that pretty-print.scm includes the
> following internal definition:
>
>   (define max-expr-width 50)
>
> (although in fact the maximum width ends up being 49)
>
>> Is there a workaround?
>
> A couple of years ago I added an undocumented #:max-expr-width keyword
> argument to pretty-print, in order to improve the formatting of
> psyntax-pp.scm.  You could use that.

Just pushed some documentation, so this bug is done.

> It would be good to redesign and rewrite our pretty-printer from scratch
> at some point.

Yes!

Andy

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