• Here is the output from the script that tries to broaden this result, 4.tthtml.pl:

  <table>
  <tr><td>a</td><td>b</td><td>c</td><td>d</td><td>e</td><td>f</td></tr>
  <tbody>
  <tr><td>a</td><td>q</td><td>c</td><td>d</td><td>e</td><td>f</td></tr>
  <tr><td>a</td><td>b</td><td>c</td><td>d</td><td>e</td><td>&#x2588;</td
  +></tr>
  <tr><td>&#x2588;</td><td>b</td><td>c</td><td>d</td><td>e</td><td>f</td
  +></tr>
  </tbody>
  </table>
  
  -------
  -------
  
  <style>
  table {
    border:0;
    border-collapse:collapse;
  }
  td {
    font-weight:700;
    text-align:center;
    line-height:200%;
    font-size: 150%;
    border:2px solid black;
    width:2em;
    height:2em
  }
  td.fill {
    background-color:black;
  }
  </style><table>
  <tr><td>a</td><td>b</td><td>c</td><td>d</td><td>e</td><td>f</td></tr>
  <tbody>
  <tr><td>a</td><td>q</td><td>c</td><td>d</td><td>e</td><td>f</td></tr>
  <tr><td>a</td><td>b</td><td>c</td><td>d</td><td>e</td><td>&#x2588;</td
  +></tr>
  <tr><td>&#x2588;</td><td>b</td><td>c</td><td>d</td><td>e</td><td>f</td
  +></tr>
  </tbody>
  </table>
  [download]

• Here is the source:

  #!/usr/bin/env perl
  use 5.16.0;
  use utf8;
  use strictures;
  binmode STDOUT, 'utf8';
  use open OUT => ':utf8';
  
  my $out_string = '
  <style>
  table {
    border:0;
    border-collapse:collapse;
  }
  td {
    font-weight:700;
    text-align:center;
    line-height:200%;
    font-size: 150%;
    border:2px solid black;
    width:2em;
    height:2em
  }
  td.fill {
    background-color:black;
  }
  </style>';
  
  
  use Text::Table::HTML;
  
  my $rows =   [
    [ "a" .. "f" ],
    [ "a",        "q", "c" .. "f" ],
    [ "a" .. "e", "\x{2588}" ],
    [ "\x{2588}", "b" .. "f" ],
    ];
  
  my $string = Text::Table::HTML::table(rows => $rows);
  say "$string";
  
  say "-------";
  $out_string .= $string;
  say "-------";
  say "$out_string";
  
  $
  [download]

  Do I have a string here, or is it something that isn't a string and I'm trying to shoehorn it into one?

• When I try to take the ascii example and put it in a place where it will get spliced into my script, I get:

  ------------string inserted
  "<table>\n<tr><td>a</td><td>b</td><td>c</td><td>d</td><td>e</td><td>f<
  +/td></tr>\n<tbody>\n<tr><td>a</td><td>q</td><td>c</td><td>d</td><td>e
  +</td><td>f</td></tr>\n<tr><td>a</td><td>b</td><td>c</td><td>d</td><td
  +>e</td><td>&#x2588;</td></tr>\n<tr><td>&#x2588;</td><td>b</td><td>c</
  +td><td>d</td><td>e</td><td>f</td></tr>\n</tbody>\n</table>\n"
  ------------string to be inserted ^^^
  Can't use string ("<table>
  <tr><td>a</td><td>b</td>"...) as a SCALAR ref while "strict refs" in u
  +se at template_stuff/html9.pm line 150.
  $
  [download]

  from:

  say "------------string inserted";
    use Text::Table::HTML;
    use Data::Dump;
  
    my $rows = [
      [ "a" .. "f" ],
      [ "a",        "q", "c" .. "f" ],
      [ "a" .. "e", "\x{2588}" ],
      [ "\x{2588}", "b" .. "f" ],
    ];
  
    my $string = Text::Table::HTML::table( rows => $rows );
  
    #say "$string";
    dd $string;
    say "------------string to be inserted ^^^";
  
    print $fh $$string;
  [download]

It looks like a string coming from Data::Dump, does it not?