When you need loops nested arbitrarily deep, think of Algorithm::Loops's NestedLoops.

If you just need the transformed values:

use Algorithm::Loops qw( NestedLoops );

my $i = NestedLoops(\@arr);
while (my @vals = $i->()) {
   print(join(' ', @vals), "\n");
}
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If you need the indexes and transformed values:

use Algorithm::Loops qw( NestedLoops );

my $i = NestedLoops([
   map { [ 0..$#$_ ] } @arr
]);
while (my @idx = $i->()) {
   my @vals = map { $arr[$_][$idx[$_]] } 0..$#idx;
   print('(', join(',', @idx), ') --> ', join(' ', @vals), "\n");
}
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