User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; sv-SE; rv:1.9.2.28)
            Gecko/20120306 Thunderbird/3.1.20
MIME-Version: 1.0
References: <55DBB7F6.1070307@clear.net.nz>           
            <55DABA1D.3050706@morningstar2.co.uk>           
            <55DCFDF7.7080305@clear.net.nz>           
            <55DC05BF.1040505@morningstar2.co.uk>           
            <55DC28E8.9090405@morningstar2.co.uk>           
            <55DDFD0A.4000901@clear.net.nz>           
            <CANQYN6wzPW4aeO0WftqthfZ_6szd6-E60OzGhZcZ1g6JM6rseg@mail.gmail.com> <55DDACCB.1070104@morningstar2.co.uk> 
            <55DF523F.2050905@clear.net.nz>
            <CANQYN6zrXjg70uJaw4dEd+_Adye0KHU90dYVmRqpR8CpiOp0_g@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Message-ID:  <55DF48BE.5030503@residenset.net>
Date:         Thu, 27 Aug 2015 19:28:30 +0200
Reply-To: Mailing list for the LaTeX3 project
              <LATEX-L@LISTSERV.UNI-HEIDELBERG.DE>
Sender: Mailing list for the LaTeX3 project <LATEX-L@LISTSERV.UNI-HEIDELBERG.DE>
From: =?UTF-8?B?TGFycyBIZWxsc3Ryw7Zt?= <Lars.Hellstrom@RESIDENSET.NET>
Subject: Re: Catcode changes
To: LATEX-L@LISTSERV.UNI-HEIDELBERG.DE
In-Reply-To:  <CANQYN6zrXjg70uJaw4dEd+_Adye0KHU90dYVmRqpR8CpiOp0_g@mail.gmail.com>
Precedence: list
Envelope-To: <rainer.schoepf@GMX.NET>
Content-Transfer-Encoding: 8bit
Status: R

Bruno Le Floch skrev 2015-08-27 12.34:
> That's much harder.  Catcode changes are probably warranted in this
> case, since teaching TeX to nest parentheses in this way is tough.

I seem to recall that I did demonstrate how to do that -- have TeX match 
parentheses in an expression, using delimited arguments rather than catcode 
changes -- in a mail to this very list several years ago... Yes, it was on 
2011-10-19 and the subject was "Re: Church booleans".

The attachment with the full implementation was included in the posting from 
the list, so I hope it also made it into the list archives. (But I don't 
really have the energy at the moment to figure out what my password is so 
that I can check.)

Lars Hellström

PS: I maintain that that approach to evaluating infix boolean expressions is 
far superior to what is currently offered in LaTeX3, but Bruno just seems to 
*love* his &&, with all its shortcomings. ;-)