Subject: Re: [xsl] XPath 3.0: Is it possible to do recursion in an anonymous function? From: Dimitre Novatchev <dnovatchev@xxxxxxxxx> Date: Sat, 13 Oct 2012 12:37:24 -0700 |
You are right, but there is an easy workaround. Here is an example with an in-line factorial function: declare option saxon:output "omit-xml-declaration=yes"; let $f := function($n as xs:integer, $f1 as function(xs:integer) as xs:integer ) as xs:integer {if($n eq 0) then 1 else $n * $f1($n -1, $f1) } return $f(5, $f) The result we get is correct: 120 Cheers, Dimitre On Sat, Oct 13, 2012 at 12:03 PM, Costello, Roger L. <costello@xxxxxxxxx> wrote: > Hi Folks, > > Is it possible to do recursion in an anonymous function? > > Example: I would like to implement an "until" function. It has three arguments: > > 1. p is a boolean function > 2. f is a function on x > 3. x is the value being processed > > Read the following function call as: decrement 3 until it is negative > $until ($isNegative, $decrement, 3) > > where > $isNegative := function($x as xs:integer) {$x lt 0} > $decrement := function($x as xs:integer) {$x - 1} > > Here's how I attempted to implement function until: > > $until := function( > $p as function(item()*) as xs:boolean, > $f as function(item()*) as item()*, > $x as item()* > ) as item()* > { > if ($p($x)) then > $x > else > $until($p, $f, $f($x)) <-- RECURSE ...THIS IS NOT ALLOWED, I THINK > } > > Is there a way to implement function until in XPath 3.0? (I know how to implement it in XSLT 3.0) > > /Roger > -- 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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