[xquery-talk] Global variables in XQuery
Jonathan Robie
jonathan.robie at datadirect.com
Wed Oct 4 12:51:23 PDT 2006
Liam Quin wrote:
> The "let" part of a FLWOR always creates new variables.
> Think of them as named constants if you prefer...
>
This is the key point. Variables in XQuery never vary, they are
constant. XQuery inherits this from other functional languages - but it
does take some getting used to if you have been using procedural
languages. On the plus side, it makes XQuery more declarative and
optimizable.
FWIW, there is some work being done on procedural extensions to XQuery,
which would allow the values of variables to be changed. But this is not
part of the current language. For instance, see this paper:
http://www.ximep-2006.org/papers/Paper-Chamberlin-Carey.pdf
Jonathan
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