In the

foreach my $n (0 .. @normal){
  if ($n%2){
    push @reverse, $normal[$n].$normal[$n+1];
  }
}
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loop, aren't you indexing beyond the end of the  @normal array? Won't this produce "Use of uninitialized value..." warnings if warnings are enabled? Shouldn't the loop range be  for my $n (0 .. $#normal-1) { ... } instead?

(And BTW: Aren't you losing an opportunity to avoid using a foreach-loop by not re-writing the loop as a map | void-context map statement? :)