@qt4cg statuses

I want to revive Mike’s idea of introducing a trace clause (#111):

Despite the recent spec including fn:message, it remains cumbersome to output intermediate results or provide progress information inside FLWOR expressions. I think that a message clause with one expression and an optional label expression…

for $item in //items
message $item/@id, 'ID: '
return string($item)

…would be a good drop-in replacement for clumsy temporary let clauses…

for $item in //items
let $_ := message($item/@id, 'ID: ')
return string($item)

The clause would be evaluated once for every tuple reaching that clause. It seems sensible to me to stick with the value/label structure, as existing trace code can build on it without further changes.

Since the evaluated value is swallowed, I have chosen message as keyword, but trace may work similarly well.

PS: I promise I’ll hold off on sharing new ideas for the upcoming weeks…

Fix #2668

Fix #2669

Given the debates we've been having about empty entries in a record versus absent entries, it would be useful to have an option on the deep-equal function to treat these as equivalent.

Perhaps "empty-as-absent" - treats map entries whose value is an empty sequence as if the entry were absent. Default false.

In the past, the number-parser option was added to fn:parse-json and fn:json-to-xml. It has been removed from fn:parse-json again (and replaced by number-format), and I think we should also remove it from fn:json-to-xml:

• In the XML representation, the original JSON representation is adopted 1:1, so the result will be lossless (which is why number-format was not introduced for this function). If really needed, it can be changed in a post-processing step.
• It seems much too specific to me, and we don’t have corresponding parser functions for other data types (null, booleans, etc.)

If we keep it, we should fix a typo (“convered”).

Fix #2458

This proposal introduces two changes, which taken together, replace the use of get(expr) in axis steps.

For JNodes, with an expression E1/E2, if E1 selects JNodes and E2 selects atomic values, then the atomic values are matched against the jkey properties of the child JNodes.

More generally, axis::{expr} (for example descendant::{$name} selects nodes on the relevant axis whose name/jkey is equal to the result of evaluating expr.