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RE: what is the meaning of literals in step expressions?

From: Howard Katz <howardk@fatdog.com>
Date: Fri, 4 Jul 2003 09:10:46 -0700
To: "Kay, Michael" <Michael.Kay@softwareag.com>, <www-ql@w3.org>
Message-ID: <IKEOLCDFPBBPPAHGNKKOKEOICFAA.howardk@fatdog.com>
RE: what is the meaning of literals in step expressions?Thanks for the
clarification. The other viewpoint (not that I'm espousing it, just pointing
it out as a point of information) is that the more rules the grammar
enforces, the less the type system (and the poor implementer :-) has to do.
Ta,
Howard
  -----Original Message-----
  From: www-ql-request@w3.org [mailto:www-ql-request@w3.org]On Behalf Of
Kay, Michael
  Sent: Friday, July 04, 2003 7:47 AM
  To: Howard Katz; www-ql@w3.org
  Subject: RE: what is the meaning of literals in step expressions?


  >
  > I just realized that the existing grammar allows expressions
  > such as "1/3", "//book/2", and "/bib//46.5/editor". Do
  > patterns such as these (with literals in step expressions)
  > have any valid semantic interpretation? What should an XQuery
  > implementation do on encountering such an expression? Thanks, Howard
  >

  The operands of "/" must be nodes, and literals are never nodes, so such
expressions will always give a type error. We have generally chosen not to
make the grammar enforce rules that are better enforced by the type system.
Writing 1/3 is just like writing "a"+"b", which is also a type error rather
than a syntax error.

  Michael Kay
Received on Friday, 4 July 2003 12:09:18 UTC

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