XML and especially XML schema are hugely complex and almost laughably difficult to bind to any mainstream programming language. It took Java over a decade to produce a binding that could (perhaps) handle an arbitrary schema. Types boil down to sums and products, I'm not convinced the designers of XML/XSD understood this. XML has so many overlapping concepts: elements, attributes, enumerations, choices, unions, sequences, lists, element/attribute groups, substitution groups, facets, simple types, complex types etc etc IMHO it's ad-hoc and ugly; we deserve better.