use DateTime;
use DateTime::Format::Strptime;
my $p = DateTime::Format::Strptime->new(on_error=>'croak',
    pattern => '%Y-%m-%d');
my $dt = $p->parse_datetime('1988-12-13');
print $dt, " -> ", $dt->epoch, "\n";
__END__
1988-12-13T00:00:00 -> 597974400