use Algorithm::Combinatorics qw[ variations_with_repetition ];;
$i = variations_with_repetition( [ 'a'..'z' ], 3 );;
$" = ''; print "@$_" while $_ = $i->next;;
aaa
aab
aac
aad
...

##</code><code>##

$" = ''; $_ = join( '', @$_ ), m[[aeiouy]] and print while $_ = $i->next;;