RosettaCodeData/Task/Permutations-by-swapping/Perl-6/permutations-by-swapping.pl6

sub insert($x, @xs) { ([flat @xs[0 ..^ $_], $x, @xs[$_ .. *]] for 0 .. +@xs) }
sub order($sg, @xs) { $sg > 0 ?? @xs !! @xs.reverse }

multi perms([]) {
    [] => +1
}

multi perms([$x, *@xs]) {
    perms(@xs).map({ |order($_.value, insert($x, $_.key)) }) Z=> |(+1,-1) xx *
}

.say for perms([0..2]);