[xsl] [XPath 3.0] Partial function application plus arity?

["Costello, Roger L." <costello@xxxxxxxxx>]

Hi Folks,

In previous discussions we seen that these 3 XPath expressions produce the
same result:

-----------
XPath #1
-----------
concat('Section', ': ', 1)

-----------
XPath #2
-----------
let $concat3 := concat#3
return $concat3('Section', ': ', 1)

-----------
XPath #3
-----------
let $concat3 := concat(?,?,?)
return $concat3('Section', ': ', 1)

Now, I would like to provide concat() a value for the first argument and leave
undefined two arguments. So I tried this:

-----------
XPath #4
-----------
let $concat3 := concat#3('Section')
return $concat3(': ', 1)

But that generates this error:

    Required item type of target of dynamic
    function call is function(); supplied value
    has item type xs:string

What is that error message saying?

What is the correct way of expressing the desired XPath?

/Roger