sub quicksort {
    return @_ unless @_ > 1;
    my $pivot = shift;
    return (
        quicksort( grep $_ < $pivot, @_ ),
        $pivot,
        quicksort( grep $_ >= $pivot, @_ ),
    );
}

##</code><code>##

sub quicksort_t {
    return @_ unless @_ > 1;
    my $pivot = shift;

    ## partition the data into 2 parts and run the standard recursive algorithm 
    ## on those two partitions in separate threads; return combined (joined) results
    my $t1 = asyncl sub{ quicksort( grep $_ <  $pivot, @_ ) }, @_;
    my $t2 = asyncl sub{ quicksort( grep $_ >= $pivot, @_ ) }, @_;
    return ( $t1->join, $pivot, $t2->join );
}

##</code><code>##

sub _quicksort_t {
    return @_ unless @_ > 1;
    my $pivot = shift;

    ## partition the data into 2 parts and run the standard recursive algorithm 
    ## on those two partitions in separate threads; return combined (joined) results
    my $t1 = asyncl sub{ quicksort( grep $_ <  $pivot, @_ ) }, @_;
    my $t2 = asyncl sub{ quicksort( grep $_ >= $pivot, @_ ) }, @_;
    return ( $t1->join, $pivot, $t2->join );
}

sub quicksort_t {
    return @_ unless @_ > 1;
    my $pivot = shift;

    ## Partition and thread to a thread helper function
    my $t1 = asyncl sub{ _quicksort_t( grep $_ <  $pivot, @_ ) }, @_;
    my $t2 = asyncl sub{ _quicksort_t( grep $_ >= $pivot, @_ ) }, @_;
    return ( $t1->join, $pivot, $t2->join );
}