Re: Functional program for "list sum"

    <xsl:param name="num" as="xs:integer" />


That means that the first argument must be an integer.

select="fn:listSum(null,(

That passes the first argument as the sequence of all element nodes with
name num, If there are no such elements  then this sequence will be
empty and you will get the  error that you show. perhaps you want to
start with 0

Also put version="2.0" on your stylesheet then you will not get
"Warning: Running an XSLT 1.0 stylesheet with an XSLT
2.0 processor


Despite calling your function Sum, it doesn't actually sum anything,
it just returns a sequence which is teh same as teh sequence supplied in
the second argument except that the first item has been replaced by the
integer supplied in the first argument.

fn:listSum(5,(1,2,3))  is (5,2,3)

David

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