use strict;
use Data::Dumper;


# The HoA below may come in varying
# sizes: from "key1" to "key 50"

my $hash = {
    'key1' => [ 1,   2,   3, 4 ],
    'key2' => [ 10,  20,  30 ],
    'key3' => [ 100, 200, 300 ],
};


# My code below is "hard-coded"
# How can I change it to accomodate
# dinamycally changing hash size above?

my @val1 = @{$hash->{'key1'}};
my @val2 = @{$hash->{'key2'}};
my @val3 = @{$hash->{'key3'}};

foreach my $val1 (@val1) {

    foreach my $val2 (@val2) {

        foreach my $val3 (@val3) {
            print "$val1 - $val2 - $val3\n";
        }
    }
}



##</code><code>##

1 - 10 - 100
1 - 10 - 200
1 - 10 - 300
1 - 20 - 100
1 - 20 - 200
1 - 20 - 300
1 - 30 - 100
1 - 30 - 200
1 - 30 - 300
2 - 10 - 100
2 - 10 - 200
2 - 10 - 300
2 - 20 - 100
2 - 20 - 200
2 - 20 - 300
2 - 30 - 100
2 - 30 - 200
2 - 30 - 300
3 - 10 - 100
3 - 10 - 200
3 - 10 - 300
3 - 20 - 100
3 - 20 - 200
3 - 20 - 300
3 - 30 - 100
3 - 30 - 200
3 - 30 - 300
4 - 10 - 100
4 - 10 - 200
4 - 10 - 300
4 - 20 - 100
4 - 20 - 200
4 - 20 - 300
4 - 30 - 100
4 - 30 - 200
4 - 30 - 300