Re: Returning item type of variable (problems with map

On 28 Mar 2014, at 16:21, Dimitre Novatchev <dnovatchev@xxxxxxxxx> wrote:

> On Fri, Mar 28, 2014 at 9:13 AM, Michael Kay <mike@xxxxxxxxxxxx> wrote:
>> Yes - but the challenge is to find out that a map is an instance of
map(xs:string, element(emp)) or whatever, if you want to know what kind of map
you have been given.
>
> Yes, we only have function-lookup() which uses the function name and
> arity -- not the exact signature. And anyway, it is to be used in
> "pull style" not in "push style".
>
> I gather that function-lookup() cannot be used for maps, although a
> map is a function. Is this right?
>

function-lookup() will only access named functions, a map is an anonymous
functions.

> Or probably there are new things coming in XPath 3.1?
>

There's no plan to do types-as-first-class-objects.

In Saxon there is an extension to access schema components including schema
types as functions -- see

http://www.saxonica.com/documentation/index.html#!functions/saxon/schema

It would be quite possible to use the same kind of model to represent item
types and sequence types.

Michael Kay
Saxonica