> And, obviously, it would be far more efficient to write the iteration:

Indeed. :-/ But it seems to work. :)

Many thanks and sorry for the slow communication, but job is very demanding at the moment.

( I should have checked CPAN for "scope" and I'm not a big fan of XS dependencies but after I saw that dave_the_m is one of the maintainers, it might be canonical. ;-)

I'll certainly have a closer look into it and will come back to it later... :)