Boh my previous answers had a slight issue (that didn't prevent Saxon
from executing them and producing the correct result) with the typing
of the "mock" function parameter $f1.

Here is this corrected:

<xsl:stylesheet  version="3.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  exclude-result-prefixes="xs">
  <xsl:output method="text"/>

  <xsl:template match="/">
     <xsl:sequence select=
       "let $f := function($n as xs:integer,
                                   $f1 as function(xs:integer,
function()) as xs:integer
                                   ) as xs:integer
                        {if($n eq 0)
                            then 1
                            else $n * $f1($n -1, $f1)
                        }
         return
            $f(5, $f)
       "/>
   </xsl:template>
 </xsl:stylesheet>


Cheers,
Dimitre

On Sat, Oct 13, 2012 at 12:47 PM, Dimitre Novatchev
<dnovatchev@xxxxxxxxx> wrote:
> Here is an equivalent XSLT-based solution -- i both cases there is no
> literal function defined -- just an inline one:
>
> <xsl:stylesheet  version="3.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
>   xmlns:xs="http://www.w3.org/2001/XMLSchema"
>   exclude-result-prefixes="xs">
>   <xsl:output method="text"/>
>
>   <xsl:template match="/">
>      <xsl:sequence select=
>        "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)
>        "/>
>    </xsl:template>
>  </xsl:stylesheet>
>
> Again, the correct result is produced:
>
> 120
>
>
> Cheers,
> Dimitre
>
> On Sat, Oct 13, 2012 at 12:37 PM, Dimitre Novatchev
> <dnovatchev@xxxxxxxxx> wrote:
>> 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.
>
>
>
> --
> 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.



-- 
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.