in reply to AI::Genetic gives me strange warnings

There are two mechanisms by which you can get the sort arguments. One mechanism is to trust that package globals $a and $b (they're not lexicals) will be defined by perl for evaluation.

The other mechanism is to use a subroutine with a ($$) prototype; then the arguments $_[0] and $_[1] will be used instead.

Maybe the second mechanism is useful for a workaround in either the inner loop or outer loop?

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