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

use Math::Combinatorics;

my $count = 0;
my $comb = 'Math::Combinatorics'->new(count => 4, data => [ 0 .. 9 ]);
++$count, say @$_ while @$_ = $comb->next_combination;
say $count;