Generate random, balanced bracket strings

gen.pl

sub gen(Int $c = 6) {
    my @l = '[' xx $c;
    my @r = ']' xx $c;
    my $s = '';
    $s ~= @l == @r ?? @l.shift
                   !! (@l + @r).rand < @l
                   ?? @l.shift
                   !! @r.shift
        while @l || @r;

    $s;
}
say gen;