variations_with_repetition in module Algorithm::Combinatorics also does what you want:

use strict;
use warnings;
use Algorithm::Combinatorics 'variations_with_repetition';

my @data = (0..9,'a'..'z');
my $iter = variations_with_repetition( \@data, 4 );
while( my $c = $iter->next ) {
    print "@$c\n";
}
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It does end though when it reaches 'zzzz'.