Qui, 2008-10-02 às 12:55 +0100, Tim Bunce escreveu:
> Like applying XPath to an XML DOM, only more general and taken
> further.
> By "more general and taken further" I'm thinking of the same kind of
> evoltion from simple regular expressions in perl5 to grammars in perl6.
> An XPath query is like a perl5 regular expression. 

During YAPC::EU::2007 (yeah... some time ago...) we had this discussion
motivated by the need to have something easier to transform parse

In that case, we were thinking about programming-language-translators
that would take the parse tree of one language, make some modifications
in the tree before emitting the other language (i.e.: turning specific
language dialects, for instance some uses of map and grep in perl5, to a
language that doesn't support map and grep, then turning that into a
different p5 construct that could be effectively translated to the
target language).

One thing we realized at that time is that XPath is good enough, even if
it seems to be adressing XML specifically, it has the concept of
"dimension" that can be extended to represent arbitrary aspects of

When we then take XQuery into account, we might have all the tools to
build an coherent tree-oriented Rule system.

xgrammar Foo {
   xtoken bar {
      'some XPath expression' <subtoken>
      { make 'some XQuery expression' }
   xtoken subtoken {
      'some other Xpath expression'
      { make 'yet another xquery expression' }

Of course we still need to think how to compose different xpath
expressions and how to make captures of it, but maybe XQuery already
solves that problem...


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