ulis: If, for some syntax analyzis, you need to strip the braces of a list, here is a tiny proc that do that.

It returns "{this is} a {nested list}" for "{{{this is} a {nested list}}}". You can control the level of stripping, also.

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ulis: This proc is wrong.

 [[striplist {{{this is}}{{a list}}}] returns  '{this is}}{{a list}' in place of '{{this is}}{{a list}}'. 

I'm trying to publish soon a better proc.

    proc striplist {text {level -1}} \
    { 
      # expose outer braces
      set text [string trim $text]
      # while text seems braced and level is not exhausted
      while { $level != 0
           && [string index $text 0] == "\{"
           && [string index $text end] == "\}"} \
      { 
        # strip outer braces and expose inners
        set text [string trim [string range $text 1 end-1]] 
        # check if this is too much
        set n1 [string first "\{" $text]
        set n2 [string first "\}" $text]
        if {$n1 != -1 && $n2 != -1 && $n2 < $n1} \
        { 
          # yes, this is too much, restitute outer braces
          set text "{$text}"
          # and stop
          break 
        }
        # check for asked nesting
        incr level -1
      }
      return $text
    }

----

Results:

  set text "{{{this is} a {nested list}}}"
  puts [striplist $text]
  -> {this is} a {nested list}
  
  set text "{{{this is} a {nested list}}}"
  puts [striplist $text 1]
  -> {{this is} a {nested list}}
  
  set text "{{{this is} a {nested list}}}"
  puts [striplist $text 2]
  -> {this is} a {nested list}

----
AEC, 2002-05-28

I use the built-in command '''join''' to do the same thing.

 set text "{{{this is} a {nested list}}}"
 {{{this is} a {nested list}}}
 %   set textt [join $text]
 {{this is} a {nested list}}
 %   set textt [join [join $text]]
 {this is} a {nested list}
 %   set textt [join [join [join $text]]]
 this is a nested list