gistfile1.pl

use 5.14.1;
use charnames ':full';
binmode(STDOUT, 'encoding(utf-8)');

my $i = 0;
my %digit = map { $i++ => $_ }
  qw(ZERO ONE TWO THREE FOUR FIVE SIX SEVEN EIGHT NINE);

my $str = $ARGV[0] || die "usage: bold 'string to bold-ify'\n";

$str =~ s<([a-z0-9])><
  my $name = $1 ge 'a' && $1 le 'z' ? "MATHEMATICAL BOLD SMALL \U$1"
           : $1 ge 'A' && $1 le 'Z' ? "MATHEMATICAL BOLD CAPITAL $1"
           : $1 ge '0' && $1 le '9' ? "MATHEMATICAL BOLD DIGIT $digit{$1}"
           : undef;
  $name ? charnames::string_vianame($name) : $1;
>gei;

say $str;