Updating variables in xquery dating sites really work
We use the terminology of "non-updating" for simple expressions.
Because of their side effects, sequential expressions must be evaluated in evaluation order, as defined in this specification.
This requires a number of extensions to the XQuery 3.0 and XQUF processing model.
[A statement is a grammatical construct which does not return anything (no XDM, no PUL) but can have side-effects.
This extension is on in Zorba by default but can be turned off.
This specification defines an extension to XQuery 3.0 and XQuery Update Facility 1.0.
The XQUF specifications take care of forbidding such ambiguous updates.