Jim,
Now that I see that there is interest in this, I will consider posting
to Bugzilla.
Thank you.
Dimitre
On Wed, Oct 24, 2012 at 8:36 AM, Jim Melton
<jim(_dot_)melton(_at_)oracle(_dot_)com> wrote:
Dimitre,
Thanks for showing us your work on this. Very interesting, I thought.
You suggested some new post-3.0 XPath features in your message. A preferred
way to let the XSLT and XML Query Working Groups know of such proposed new
requirements would be to post them on W3C's public Bugzilla instance, using
Product = "XPath / XQuery / XSLT" and Component = "XQuery 3.1 Requirements
and Use Cases". (Note that there is no assurance that there will ever be
another version of XPath, XQuery, or XSLT after the current 3.0 versions
under development, nor that any such future version will be designated
"3.1".)
You can locate that Bugzilla instance at
https://www.w3.org/Bugs/Public/enter_bug.cgi
Hope this helps,
Jim
At 10/24/2012 07:32 AM, Dimitre Novatchev wrote:
A few months ago I had the pleasure to do "all XPath programming".
I developed the Binary tree data type and the Set data type
essentially completely in XPath 3.0.
These can be found in my blog, respectively at:
http://dnovatchev.wordpress.com/2012/01/09/the-binary-search-tree-data-structurehaving-fun-with-xpath-3-0/
and
http://dnovatchev.wordpress.com/2012/01/12/the-set-datatype-implemented-in-xpath-3-0/
At the time this happened accidentally. I don't like to work with
XQuery, but at that time Saxon's XSLT 3.0 processor didn't fully
implement higher order functions. Saxon's XQuery 3.0 did, so I
reluctantly used XQuery 3.0 in my work. Doing so, I planned to move my
whole code to XSLT 3.0 --whenever Saxon's XSLT 3.0 processor was ready
for this (and now, in version 9.4 it is). Therefore I essentially
coded everything as much in pure XPath 3.0 as possible.
This experience clearly showed to me that it is possible to use XPath
3.0 as a stand-alone programming language. This has many benefits, and
one of them is that XPath-only code is fully transferrable between
XSLT and XQuery.
At the end of my latest blog post "Recursion with anonymous (inline)
functions in XPath 3.0", I list a number of nice features we still
need in XPath as a programming language, that could be added in a
future, post-3.0 version:
1. Stand-alone XPath processors.
2. Import/include directives for XPath-only files (expression-files).
3. Separate packaging/compilation of XPath-only programs.
4. New data structures such as tuples.
5. Generics – parametric data types.
Cheers,
Dimitre
On Wed, Oct 24, 2012 at 4:55 AM, Costello, Roger L.
<costello(_at_)mitre(_dot_)org>
wrote:
Thanks a lot Michael for the explanation. Fantastic!
Below is a summary of my question plus Michael's answer (slightly
expanded).
The XPath 3.0 specification says this:
XPath 3.0 is a composable language
What does that mean?
It means that every operator and language construct allows any XPath
expression to appear as its operand (subject only to operator precedence
and
data typing constraints).
For example, take this expression:
3 + ____
The plus (+) operator has a left-operand, 3. What can the right-operand
be? Answer: any XPath expression! Let's use the max() function as the
right-operand:
3 + max(___)
Now, what can the argument to the max() function be? Answer: any XPath
expression! Let's use a for-loop as its argument:
3 + max(for $i in 1 to 10 return ___)
Now, what can the return value of the for-loop be? Answer: any XPath
expression! Let's use an if-statement:
3 + max(for $i in 1 to 10 return (if ($i gt 5) then $i*3 else $i*2)))
The fact that XPath is a composable language is very cool and very
powerful.
Contrast this with XSLT, which is not fully composable: XPath
expressions can be used as operands to XSLT instructions, but not the other
way around. Similarly Java has constructs called statements that
cannot be nested inside expressions.
/Roger
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Cheers,
Dimitre Novatchev
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Truly great madness cannot be achieved without significant intelligence.
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-------------------------------------
To avoid situations in which you might make mistakes may be the
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------------------------------------
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-------------------------------------
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-------------------------------------
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Cheers,
Dimitre Novatchev
---------------------------------------
Truly great madness cannot be achieved without significant intelligence.
---------------------------------------
To invent, you need a good imagination and a pile of junk
-------------------------------------
Never fight an inanimate object
-------------------------------------
To avoid situations in which you might make mistakes may be the
biggest mistake of all
------------------------------------
Quality means doing it right when no one is looking.
-------------------------------------
You've achieved success in your field when you don't know whether what
you're doing is work or play
-------------------------------------
Facts do not cease to exist because they are ignored.
-------------------------------------
Typing monkeys will write all Shakespeare's works in 200yrs.Will they
write all patents, too? :)
-------------------------------------
I finally figured out the only reason to be alive is to enjoy it.
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