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Date:         Mon, 29 Aug 2011 11:37:43 +0100
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From: Joseph Wright <joseph.wright@MORNINGSTAR2.CO.UK>
Subject: Re: Removing braces in a token list
To: LATEX-L@listserv.uni-heidelberg.de
In-Reply-To:  <bs7n95ikt65p$.dlg@nililand.de>
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Status: R

On 29/08/2011 09:43, Ulrike Fischer wrote:
> Assuming that I have a token list variable like this:
> 
> \tl_set:Nn \l_temp_tl { a b c {e f} g {h} i }.
> 
> What is the right way to remove the inner braces and convert it to 
> 
> { a b c e f g h i } 
> 
> ? (spaces don't matter)
> 
> (I want to loop through the list, but I need simply chars as
> arguments)

The is no pre-build 'strip_braces' function at present. You don't say if
we are talking one set of braces or multiple sets. For the former case,
a simple 'do nothing' loops would be easiest:

  \RequirePackage{expl3}
  \ExplSyntaxOn
  \tl_new:N \l_temp_tl
  \tl_set:Nn \l_temp_tl { a b c {e f} g {h} i }
  \tl_set:Nx \l_temp_tl
    { \tl_map_function:NN \l_temp_tl \exp_not:n }
  \tl_show:N \l_temp_tl
--
Joseph Wright