sub meld_columns {
  my ($arrays, @arrNames) = @_;
  my ($maxIdx) = sort { $b<=>$a } map {$#$_} @{$arrays}{@arrNames};
  my @outarray = map {
    my $i = $_;  # keep track of the current "row" to use in inner map block
    # get the respective element from each array.
    # If we're beyond the individual array length, just use "\t".
    # Also glue all cols together w/a "\t"
    join "\t", map { $i <= $#$_ ? $_->[$i] : "\t" } @{$arrays}{@arrNames}
  } 0..$maxIdx;
}
my %arrayHolder = map { $_ => [] } 'a' .. 'z';   # build the initial data structure (instead of named arrays)
my @out = meld_columns( \%arrayHolder, 'a' .. 'h' );  # meld just A through H
my @out = meld_columns( \%arrayHolder, 'f', 'a', 'c' );  # meld just F A C, in that order.