use Modern::Perl;
use Regexp::Assemble;

open my $HAMLET_IN, '<', 'hamlet.txt' or die $!;
my $hamlet;
{
    local $/; # slurp mode
    $hamlet = <$HAMLET_IN>;
}

my $ra = Regexp::Assemble->new(file => 'names.txt')->re;

$hamlet =~ s/$ra/*****/g;

open my $HAMLET_OUT, '>', 'hamlet_new.txt' or die $!;
print $HAMLET_OUT $hamlet;