I've found that proposition to introduce tuples and maps to xslt/xquery type system has not found a support:

At the joint meeting of the XSL and XQuery Working groups 2008-06-23 it was decided that a change of this nature would be too large for the next "point" release of the Recommendations. The request for new functionality will be considered for a future "main" release.

Boor> *****!

Pessimist> Ah, there won't be tuples and maps in xslt/xquery...

Optimist> Wow, chances are good to see this addition by the year 2018!