LISTSERV mailing list manager LISTSERV 16.0

Help for LATEX-L Archives


LATEX-L Archives

LATEX-L Archives


LATEX-L@LISTSERV.UNI-HEIDELBERG.DE


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Proportional Font

LISTSERV Archives

LISTSERV Archives

LATEX-L Home

LATEX-L Home

LATEX-L  October 2011

LATEX-L October 2011

Subject:

Re: Church booleans

From:

Bruno Le Floch <[log in to unmask]>

Reply-To:

Mailing list for the LaTeX3 project <[log in to unmask]>

Date:

Sat, 15 Oct 2011 21:55:18 -0400

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (71 lines)

Is anyone out there using \if_bool:N or \if_predicate:w? No occurrence
in TeXlive 2011, and if we switch to Church booleans, those functions
would have to go.

> Provided it really does not change the interface in any way, there
> should no problem with altering the internals.

I've been trying to make the change. The end-user interface is not
changed, but since booleans become weird beasts (rather than the
simple 0/1 switch), they are pretty much impossible to manipulate
before the machinery is setup. The problem is then that expl3 and
l3bootstrap need to manipulate \l_expl_status_bool very early on. I
haven't found a clean way to resolve this issue yet, so I'm a bit
stuck.

At the end of the day, Church booleans have a definite practical
advantage, with non-expandable conditionals in \bool_if:nTF. I'm
starting to dislike them, though, from an aestetic point of view,
because \char"1 looks nicer than "\marker { \use_i:nn }" (with
braces).

>> - Change in the priority of the various operators, to be ! > && > ||.
>> I believe that this should be changed eventually. It is tricky to get
>> right, but I can do that in a couple of week if the general feeling is
>> that we should change.
>
> We probably should consider this, as it does seem that this is a general
> feature of boolean logic.

I've got this pencilled for after some regex fixes/improvements.
(Although I first need to get my system back working, as I don't feel
like just -reverting- my past few hour's work.)

>> - Change in the interface to use "not", "and" and "or" instead of "!",
>> "&&" and "||". I do prefer how boolean expressions look like with "&&"
>> and "||", but "&" makes our lifes a little bit awkward in alignments
>> (can be made fully robust, with a performance cost ~10-30%?).
>
> I'm intrigued by the 'fully robust' statement here: I've had some
> problems with \halign's, where if you end up with nested Appendix D
> tricks then all sorts of trouble starts.

In the process of answering your question, I realize that \bool_if:nTF
doesn't like being put in the u-part of an alignment preamble (the
part before the cell's contents). Actually, I'm getting very confused
about all that :(.

>>> etoolbox goes with the simple "and", "not" and "or", and to me this
>>> seems like a sensible approach. If that is done, there would need to be
>>> transitional support for the current syntax, of course.
>>
>> We can support both syntaxes (temporarily or forever) with no
>> performance cost compared to just "&&" and "||". Dropping "&&" and
>> "||" in favor of "and " and "or" improves performance a little.
>>
>> Switching to "and", "or", "not" raises the question of whether to add
>> "xor", which is currently missing. That makes priority handling
>> tougher, so I'm only half keen on that.
>
> I don't see why you'd add "and"/"or"/"not" unless the aim was to remove
> "&&"/"||"/"!". There are places where alternative syntaxes are helpful,
> but I don't see that here.

A missing xor function is pretty much my only argument here. Although
I guess that we could add some ++ or VV or whatever notation is
standard for xor.

I'll try to understand how robust we can be within alignments.

Regards,
Bruno

Top of Message | Previous Page | Permalink

Advanced Options


Options

Log In

Log In

Get Password

Get Password


Search Archives

Search Archives


Subscribe or Unsubscribe

Subscribe or Unsubscribe


Archives

July 2019
April 2019
March 2019
February 2019
January 2019
December 2018
November 2018
October 2018
September 2018
August 2018
June 2018
May 2018
April 2018
February 2018
January 2018
December 2017
September 2017
August 2017
July 2017
June 2017
May 2017
April 2017
March 2017
February 2017
January 2017
December 2016
July 2016
April 2016
March 2016
February 2016
January 2016
October 2015
September 2015
August 2015
July 2015
June 2015
May 2015
April 2015
March 2015
February 2015
January 2015
December 2014
November 2014
October 2014
September 2014
August 2014
July 2014
June 2014
May 2014
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
October 2013
August 2013
July 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
September 2012
August 2012
July 2012
June 2012
May 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
May 2010
March 2010
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
March 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
September 2007
August 2007
June 2007
May 2007
March 2007
December 2006
November 2006
October 2006
August 2006
July 2006
June 2006
May 2006
April 2006
March 2006
February 2006
November 2005
October 2005
September 2005
August 2005
May 2005
April 2005
March 2005
November 2004
October 2004
August 2004
July 2004
May 2004
April 2004
March 2004
February 2004
January 2004
December 2003
October 2003
August 2003
July 2003
June 2003
May 2003
April 2003
March 2003
February 2003
January 2003
December 2002
October 2002
September 2002
August 2002
July 2002
June 2002
March 2002
December 2001
October 2001
September 2001
August 2001
July 2001
June 2001
May 2001
April 2001
March 2001
February 2001
January 2001
December 2000
November 2000
October 2000
September 2000
August 2000
July 2000
May 2000
April 2000
March 2000
February 2000
January 2000
December 1999
November 1999
October 1999
September 1999
August 1999
May 1999
April 1999
March 1999
February 1999
January 1999
December 1998
November 1998
October 1998
September 1998
August 1998
July 1998
June 1998
May 1998
April 1998
March 1998
February 1998
January 1998
December 1997
November 1997
October 1997
September 1997
August 1997
July 1997
June 1997
May 1997
April 1997
March 1997
February 1997
January 1997
December 1996

ATOM RSS1 RSS2



LISTSERV.UNI-HEIDELBERG.DE

Universität Heidelberg | Impressum | Datenschutzerklärung

CataList Email List Search Powered by the LISTSERV Email List Manager