Oh cool! Version control is useful. I might give it a shot sometime. I didn't have anything of the sort.

If you're curious, the tool I came up with had a DSL like this:

  $excom = from:example.com
  $exorg = from:(example.org OR example.net)
  if ($excom AND $exorg) AND -(to:me OR in:spam)
    archive
    if cc:person
      label "Person"
    end
  end

and it'd auto-translate to this:

  <?xml version='1.0' encoding='UTF-8'?>
  <feed xmlns='http://www.w3.org/2005/Atom' xmlns:apps='http://schemas.google.com/apps/2006'>
    <entry>
      <category term='filter'></category>
      <apps:property name='hasTheWord' value='(from:example.com from:{example.org example.net}) -{to:me in:spam}'/>
      <apps:property name='shouldArchive' value='true'/>
    </entry>
    <entry>
      <category term='filter'></category>
      <apps:property name='hasTheWord' value='(from:example.com from:{example.org example.net}) -{to:me in:spam} cc:person'/>
      <apps:property name='label' value='Person'/>
    </entry>
  </feed>

which it would translate back to this:

  if (from:example.com from:{example.org example.net}) -{to:me in:spam}
    archive
  end
  if (from:example.com from:{example.org example.net}) -{to:me in:spam} cc:person
    label "Person"
  end

It didn't treat the filter as a blob (it actually parsed it and removed quotes etc. if appropriate) but it also didn't really change the underlying language either.

But it had variable and did let you nest conditions which made it easier to write some things. (Or so I hoped. In the end I didn't feel it was worth it...)