I found a version that works. In the original version I must not have been using tail recursion correctly. Here is the version that works. Can anyone explain why the first version doesn't properly trigger tail recursion?

``` xquery version "3.1";

declare function local:get-random-numbers($how-many as xs:integer, $generator as map(*), $accumulator) { if ($how-many ge 1) then local:get-random-numbers($how-many - 1, $generator?next(), ($accumulator, $generator?number)) else $accumulator };

declare function local:get-random-numbers($how-many as xs:integer) { local:get-random-numbers($how-many, random-number-generator(), ()) };

let $n := 2000 return local:get-random-numbers($n) => count() ```

On Mon, May 11, 2020 at 5:20 PM Joe Wicentowski joewiz@gmail.com wrote:

Hi all,

I encountered a stack overflow error with the following code, which is designed to return as many random numbers as the user requests. BaseX's error suggested, "Try tail recursion?" I think I am already using tail recursion. Changing the $n variable from 1407 to 1406 or lower avoids the error. Any number 1407 or higher triggers the error.

Thank you for any hints! Joe

xquery version "3.1";

declare function local:get-random-numbers($how-many as xs:integer,
$generator as map(*)) {
    if ($how-many ge 1) then
        (
            $generator?number,
            local:get-random-numbers($how-many - 1, $generator?next())
        )
    else
        ()
};

declare function local:get-random-numbers($how-many as xs:integer) {
    local:get-random-numbers($how-many, random-number-generator())
};

let $n := 1407
return
    local:get-random-numbers($n) => count()