Thanks, Christian.

By the way, I found a workaround for my immediate need: putting all the function-lookup usage in module functions instead of a global variable.

Regards, Amanda

On Monday, August 12th, 2024 at 4:43 AM, Christian Grün christian.gruen@gmail.com wrote:

Hi Amanda,

It is high time to tackle an existing GitHub issue that most likely relates to the same bug [1].

Thanks for your observation, Christian

[1] https://github.com/BaseXdb/basex/issues/1095

On Fri, Aug 9, 2024 at 5:51 PM Amanda Galtman galtmana@proton.me wrote:

...

Hi, all.

I'm seeing an error in BaseX when I use function-lookup in both a global variable and a function, where the function relies on the variable. I reduced the situation to the following small query:

xquery version "3.1"; declare variable $local:lookup := function-lookup(QName("nonexistent", "nonexistent"), 1); declare function local:myfcn() { let $f := ($local:lookup, function-lookup(QName('http://www.w3.org/2005/xpath-functions%27,%27string'), 1))[1] return $f('a') }; local:myfcn()

When I run it with BaseX 11.1, I get [XQDY0054] Static variable depends on itself: $local:lookup

When I run it with Saxon-HE 12, I don't get this error.

Is there anything I can do in my code to avoid this error?

Thanks, Amanda

Christian, thanks very much.

I returned to my actual code, and it works with the latest snapshot dated today.

By the way, I also retried the variations I had created when trying to explore workarounds, and one of them still doesn't work with the latest snapshot. It's not blocking me, but in case it is helpful, I reduced it to another small query that reproduces the error with today's snapshot. I know you said you fixed part of the problem, so you might not be surprised that the following code still triggers the error.

xquery version "3.1";

declare variable $variant := if (exists(function-lookup(QName('nonexistent','nonexistent'), 0))) then ( (: not relevant :) ) else function-lookup(QName('http://www.w3.org/2005/xpath-functions%27,%27string'), 1);

declare variable $variant-fcns := $variant;

declare function local:fcn() { $variant-fcns('abc') };

local:fcn()

The levels of indirection (variable, variable, function, function call) seem to be relevant for the problem. If I make the code more direct, it works.

Regards, Amanda

On Monday, August 12th, 2024 at 5:16 AM, Christian Grün christian.gruen@gmail.com wrote:

I managed to fix a part of the dependency problem. Your query should now be executable with the latest snapshot [1]. – Christian

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

On Fri, Aug 9, 2024 at 5:51 PM Amanda Galtman galtmana@proton.me wrote:

...

Hi, all.

I'm seeing an error in BaseX when I use function-lookup in both a global variable and a function, where the function relies on the variable. I reduced the situation to the following small query:

xquery version "3.1"; declare variable $local:lookup := function-lookup(QName("nonexistent", "nonexistent"), 1); declare function local:myfcn() { let $f := ($local:lookup, function-lookup(QName('http://www.w3.org/2005/xpath-functions%27,%27string'), 1))[1] return $f('a') }; local:myfcn()

When I run it with BaseX 11.1, I get [XQDY0054] Static variable depends on itself: $local:lookup

When I run it with Saxon-HE 12, I don't get this error.

Is there anything I can do in my code to avoid this error?

Thanks, Amanda

Hi Amanda,

The last query you reported back to us is now evaluated successfully [1].

In addition, XQuery 4 will allow all of us to write self-referencing variable declarations (it’s already supported by the latest snapshot):

declare variable $factorial := fn($x) { if($x > 1) then $x + $factorial($x - 1) else $x }; $factorial(5)

All the best, Christian

[1] https://github.com/BaseXdb/basex/issues/2324#issuecomment-2288790599

On Wed, Aug 14, 2024 at 3:43 PM Christian Grün christian.gruen@gmail.com wrote:

…thanks. I already guessed it wasn’t that easy ;) I’ve added it to [1].

In general, I hope we could get completely rid of self-dependency checks. It was only defined for variables, not for functions, and I cannot see why we still need it today. We are currently discussing this topic for version 4.0 [2].

Best, Christian

[1] https://github.com/BaseXdb/basex/issues/2324 [2] https://github.com/qt4cg/qtspecs/issues/1379

On Wed, Aug 14, 2024 at 1:02 PM Amanda Galtman galtmana@proton.me wrote:

...

Christian, thanks very much.

I returned to my actual code, and it works with the latest snapshot dated today.

By the way, I also retried the variations I had created when trying to explore workarounds, and one of them still doesn't work with the latest snapshot. It's not blocking me, but in case it is helpful, I reduced it to another small query that reproduces the error with today's snapshot. I know you said you fixed part of the problem, so you might not be surprised that the following code still triggers the error.

xquery version "3.1";

declare variable $variant := if (exists(function-lookup(QName('nonexistent','nonexistent'), 0))) then ( (: not relevant :) ) else function-lookup(QName(' http://www.w3.org/2005/xpath-functions%27,%27string'), 1);

declare variable $variant-fcns := $variant;

declare function local:fcn() { $variant-fcns('abc') };

local:fcn()

The levels of indirection (variable, variable, function, function call) seem to be relevant for the problem. If I make the code more direct, it works.

Regards, Amanda

On Monday, August 12th, 2024 at 5:16 AM, Christian Grün < christian.gruen@gmail.com> wrote:

I managed to fix a part of the dependency problem. Your query should now be executable with the latest snapshot [1]. – Christian

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

On Fri, Aug 9, 2024 at 5:51 PM Amanda Galtman galtmana@proton.me wrote:

...

Hi, all.

I'm seeing an error in BaseX when I use function-lookup in both a global variable and a function, where the function relies on the variable. I reduced the situation to the following small query:

xquery version "3.1"; declare variable $local:lookup := function-lookup(QName("nonexistent", "nonexistent"), 1); declare function local:myfcn() { let $f := ($local:lookup, function-lookup(QName(' http://www.w3.org/2005/xpath-functions%27,%27string'), 1))[1] return $f('a') }; local:myfcn()

When I run it with BaseX 11.1, I get [XQDY0054] Static variable depends on itself: $local:lookup

When I run it with Saxon-HE 12, I don't get this error.

Is there anything I can do in my code to avoid this error?

Thanks, Amanda

On Wed, 2024-09-18 at 13:08 +0200, Christian Grün wrote:

In addition, XQuery 4 will allow all of us to write self-referencing variable declarations (it’s already supported by the latest snapshot):

declare variable $factorial := fn($x) {   if($x > 1) then $x + $factorial($x - 1) else $x }; $factorial(5)

Hmm, what if there's a $factorial in scope already? (this is a technique i teach for taking advantage of closures to hide data)

...

On Thu, 2024-09-19 at 09:01 -0400, Liam R. E. Quin wrote:

\ Hmm, what if there's a $factorial in scope already? (this is a technique i teach for taking advantage of closures to hide data)

Many thanks to Christian for taking the time to explain to me this isn’t a problem - the change provided a meaning for something that had previously been an error, and also only affecs XQuery.

...

If I use $x * $factorial($x - 1)

True, it should have been multiplication; thanks.

I get an out-of-range error as of $factorial(21).

Integers in BaseX are limited to 64bit (that’s something the spec allows). You can use decimals to work with greater numbers:

declare variable $factorial := fn($x) { if($x > 1) then $x * $factorial($x - 1) else $x }; $factorial(1000.0)

If you need even larger results, you can use a tail-call-optimized variant…

declare variable $factorial := fn($x, $result) { if($x > 1) then $factorial($x - 1, $x * $result) else $result }; $factorial(100000.0, 1)

…or fold-left:

fold-left(1 to 100000, 1.0, op('*'))

Hope this helps, Christian