Re: XQuery (and XML) vs LISP

dawn wrote:
> Jan Hidders wrote:
>

>>dawn wrote:
>>
>>>Jan Hidders wrote:
>>>
>>>
>>>>I think the answer is, vaguely, yes. :-) You can think of the tree is a
>>>>binary relation, and if you want access to all descendants the system
>>>>could provide conceptually the transitive closure to you (so for the
>>>>binary table R you could for example use R* as the notation for its
>>>>transitive closure) and from there you could specify your queries as
>>>>usual. Most XPath queries would then translatie to simple
>>>>SELECT-FROM-WHERE queres.
>>>
>>>If they are not nested relations but nested ordered lists, as possible
>>>with XML documents, then you would lose information this way, right?
>>
>>Right. But you could add an extra binary relation that defines the order.

That depends of course upon the tools, and note we were talking about a hypothetical extension of relational tools.

> I keep meaning to look at XQuery
> to see if it handles output as in the old pizza example with multiple
> multivalues, such as the following output (sorry for dots in effort to
> get good enough spacing)

Please use a fixed-with font if you want dependable spacing.

> PizzaName.....Crust.........Meats...............Veggies.........Cheeses
> ================================================
> OurFamous.....DeepDish...Pepperoni.........Mushrooms....Parmesan
> .......................................Sausage................................Moz
> .......................................Ham
>
> Everything.......Thick.........Pepperoni.........Olivies...........Moz
> .......................................Ham.................Onions..........Provolone
> ...............................................................Peppers

Provided you reformulate it such that the output is in XML the answer is "that is what it was designed to do".

• Jan Hidders