#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

use Data::Walk;

for my $arr ([ [1, 1], 2, [1, 1] ], # 10
             [ 1, [4, [6]]],        # 27
            ) {
    my $sum = 0;
    walk sub { ref $_ or $sum += $_ * ($Data::Walk::depth - 1) }, $arr;
    say $sum;
}