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.
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!
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