use strict;
use warnings;
use Template;

my @rows = (
   { foo => 1, bar => 1, baz => 1 },
   { foo => 2, bar => 2, baz => 2 },
   { foo => 3, bar => 3, baz => 3 },
   { foo => 4, bar => 4, baz => 4 },
);

my @titles = sort keys %{$rows[0]};

my $t = Template->new();
$t->process(\*DATA, { rows => \@rows, titles => \@titles });

__END__
<table>
   <tr>
   [%- FOREACH title = titles %]
      <th>[% title %]</th>
   [%- END %]
   </tr>
   [%- FOREACH terms = rows %]
   <tr>
      [%- FOREACH term = terms.keys.sort %]
      <td>[% terms.$term %]</td>
      [%- END %]
   </tr>
   [%- END %]
</table>