XQuery from the Experts: A Guide to the W3C XML Query Language

Types in XQuery

Up to now, we have not spent much time discussing types, but the type system of XQuery is one of the most eclectic, unusual, and useful aspects of the language. XML documents contain a wide range of type information, from very loosely typed information without even a DTD, to rigidly structured data corresponding to relational data or objects. A language designed for processing XML must be able to deal with this fact gracefully; it must avoid imposing assumptions on what is allowed that conflict with what is actually found in the data, allow data to be managed without forcing the programmer to cast values frequently, and allow the programmer to focus on the documents being processed and the task to be performed rather than the ...