it would seem that there's a typo/issue with the signature (and final example) for array:sort[1,2]. Shouldn't the signature for array:sort read:

array:sort(

  $array        as array(*),

  $collation   as xs:string?                                      := fn:default-collation(),

  $key           as fn(item()*) as xs:anyAtomicType* := fn:data#1

) as item()* 

(cribbed from the qt4cg.org specs[3])? Unless I'm misreading the signature... in which case, excuse me!

Additionally, the current signature for array:sort seems to be in approximate alignment with array:sort-by, which is missing from our lovely BaseX docs' array page. To further my confusion, it looks like the examples from the qt4cg.org array:sort-by[4] signature work generally in my BaseX 12.0. Could that be added, or is the function still waiting in the BaseX wings? :)

Best wishes,

Bridger

[1] https://docs.basex.org/main/Array_Functions#array:sort

[2] the example `array:sort( [ 1, 2, 3 ], keys := fn($n) { -$n })` throws an error in BaseX 12.0:

[XPST0017] array:sort(array[,collation,key]): Unknown keyword: keys. 

I'll update the example if I may please have access, otherwise, change `keys` to `key`, please. 

[3] https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-array-sort

[4] https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-array-sort-by