If you want to avoid programming in your HTML files and you want HTML that can be previewed and editted in HTML tools then Petal is there already.

Your second point I agree with: Petal does maintain HTML that can be previewed and edited in HTML tools.

But I disagree with your first point. I think Petal allows for programming in HTML. Sure the syntax of the programming language looks a bit different, but it's still programming in my book. And in a previous post you literally said: "petal's loops" --- now since you said that Petal had loops and since loops are a programming construct, you can program in petal...

begin round two of fergal versus princepawn :) -- round one took place here

Let's compare HTML::Seamstress, Template and Petal briefly:

condition

petal

  <span tal:condition="true:user/is_authenticated">
    Yo, authenticated!
  </span>
[download]

tt

[% IF user.is_authenticated %]
     Yo, authenticated!
[% END %]
[download]

seamstress

 <div class="auth_dialog">
  <span sid="authed">
    Yo, authenticated!
  </span>
  <span sid="not_authed">
    NOT authed
  </span>
 </div>
[download]

use html::auth_dialog;

 my $tree = html::auth_dialog->new;

 $tree->highlander
    (auth_dialog =>
     [
      authed => sub { $_[0]->authenticated }
      not_authed => sub { 1 }
     ],
     $model
    );

  print $tree->as_HTML;
[download]

loop

petal

  <tag tal:repeat="element_name EXPRESSION">
     blah blah blah
  </tag>
[download]

tt

[% FOREACH s IN EXPRESSION %]
   * [% s %]
[% END %]
[download]

seamstress

  <div class="elemid">
     blah blah blah
  </div>
[download]

my $li = $tree->look_down(class => 'elemid');

  my @items = qw(bread butter vodka);

  $tree->iter($li => @items);
[download]

[tag://html,templating,seamstress]
[download]