Re: [Exist-open] Article: Higher-order functions in XQuery 3.0

[Florent G. <li...@fg...>]

Wolfgang Meier wrote:

  Hi,


> http://demo.exist-db.org/exist/apps/wiki/blogs/eXist/HoF


  Great article, thanks Wolfgang!  Just one note, about the example
for currying:

    let $f := string-join(?, " ") return $f(("Hello", "world!"))

  I'm not sure this is the best example possible, because of the "one
param sequence with two strings" gotcha.  One has to spot (and
understand) the meaning of the embedded parens, which is not always
abvious to (even not so-) beginners.  If one fails to spot it (or to
understand it), then one can see two params there...  Maybe one of the
following could be more clear?

    let $f := contains(?, 'world')
    return
      $f('Hello, world!')

or:

    declare function my:add($lhs as xs:integer, $rhs as xs:integer)
      as xs:integer
    {
      $lhs + $rhs
    };

    let $f := my:add(10, ?)
    return
      $f(32)

  It's good to see articles about new XQuery/XPath/XSLT 3.0 features,
especially about first-class citizen functions and higher-order
functions! (and to see them implemented in eXist :-p)

  Regards,

-- 

Florent Georges
http://fgeorges.org/
http://h2oconsulting.be/