A little note:

let $_DEBUG := trace(count($node), '#node: ') return name($node)}

With XQuery 4, you can use fn:message to avoid unused variables (the official successor of prof:dump) [1]:

message(count($node), '#node: '), name($node)}

[1] https://docs.basex.org/12/Standard_Functions#fn:message

On Wed, Apr 9, 2025 at 11:18 PM Hans-Juergen Rennau hrennau@yahoo.de wrote:

Simply phantastic! Simply ... BaseX!

Thank you, greetings - Hans-Jürgen

Am Mittwoch, 9. April 2025 um 21:44:11 MESZ hat Christian Grün < christian.gruen@gmail.com> Folgendes geschrieben:

Hi Hans-Jürgen,

Thanks for the observation. A simplified version of your query is:

let $a := 'x' let $b := if($a) then (<a/>, <b/>) else error() return $b/name()

The problem has been fixed in the latest snapshot [1].

Best, Christian

[1] https://files.basex.org/releases/latest/

On Wed, Apr 9, 2025 at 8:29 PM Hans-Juergen Rennau hrennau@yahoo.de wrote:

Dear BaseX people,

I have encountered a bug (?). Please consider this code:

= = = = = = = = = begin = = =

declare namespace f="http://weatherreport.org/heavyweather";

declare function f:relatedNames($node, $relationship) as xs:string* { let $fnName := function($node) { let $_DEBUG := trace(count($node), '#node: ') return name($node)}

let $items :=
    switch($relationship)
    case 'child' return $node/*
    default return error()
return
    $items/$fnName(.) => distinct-values() => sort() => string-join(',

') };

let $doc := <doc><a/><b/><c/></doc> return f:relatedNames($doc, 'child')

= = = = = = = = = end = = =

= = = = = = = = = output = = = #node: 3 Stopped at C:/projects/foxpath-examples/pre-balisage/problem-basex2.xq, 15/25: [XPTY0004] Item expected, sequence found: (<a/>, <b/>, <c/>). = = = = = = = = = = = = = = = =

The call $fnName(.) receives a single item, but three items arrive at the function item!

With kind regards, Hans-Jürgen

PS: The funny switch() seems to play a part in the game, when I removed it, the issue vanished. PPS: BaseX 11.8 [Standalone]