#!env raku

multi combine (@a, $b) {
    if @a[0] ~~ Int and @a[1] ~~ Int {
        return [ @a, [@a[0], $b] ];
    }

    [|@a, [@a[0][0], $b]]
};

multi combine ($a, $b) {
    $[$a, $b];
};

(reduce &combine, 1..8).raku.say;