Well - but are such concerns related to using maps as the output? I do not
think so, and therefore I suggest to avoid mixing specific how-to's with
general challenges. By now you know the idiom how to construct maps
dynamically, as you had already known how to construct node trees dynamically.
I agree with Graydon - best to stick to specific questions. General questions
are also welcome, but they should be phrased very carefully, in order to enable
meaningful answers. A yardstick worth trying is to pose the question in the
form "How can I ..."? or "How should one ..."? If you try, for example, to
construct a question starting with "How can I" and then introducing referential
integrity, you may find it difficult to come up with a question making real
sense.
Graydon wrote: "Understanding the whole comes from understanding an
accumulation of parts and understanding the individual parts comes from making
specific mistakes"
Yes, but I would like to add something: PRINCIPLES. XQuery is a passionately
principled language, and it is of prime importance to grasp the principles - a
process that takes time, but one should be aware of it and welcome it. Most
important is to understand the "everything-is-an-expression principle", which
makes the language composable - expressions are defined in terms of operands
which are expressions. Another key principle is the Effectvie Boolean Value,
defined by a little mantra mapping value to boolean value. (With a couple of
nasty pitfalls!) And, of course, the underlying data model - XDM - with its
beautiful stream of consciousness "Information is a value. A value is a
sequence of items. An item is a node, or an atom, or a mapping. A node has one
of six kinds. An atom is a string plus a schema type. A mapping is a mapping of
values to value, can be a map, or an array, or a function item." The firmer
your understanding of the principles, the less your need to "try out" - you
know.
Kind regards,Hans-Jürgen
Am Freitag, 27. Mai 2022, 15:38:12 MESZ hat Markus Elfring
<markus.elfr...@web.de> Folgendes geschrieben:
> Gaps? First, to avoid a misunderstanding: whereas map keys must not be the
> empty sequence, map values may.
Special data sources might contain challenges for further clarification of
the desired referential integrity.
Regards,
Markus
