Thanks for the advertisement. :)

I'll also point out that /^\d+$/ isn't a great integer check. \d allows more characters than the digits 0 to 9. It also allows a whole bunch of other Unicode digit characters, which 99% of the time, you probably didn't really intend to allow. So use /^[0-9]+$/ which is barely any more typing.

I'll also just give a quick demo of:

package Person;
use Moo;
use Types::Standard 'Int';
 
has name => (is => 'rw');
has age  => (is => 'rw', isa => Int->where(q{ $_ > 0 }));
 
1;
[download]

... as a simple way to prohibit negative integers. Or even:

package Person;
use Moo;
use Types::Common::Numeric 'PositiveInt';
 
has name => (is => 'rw');
has age  => (is => 'rw', isa => PositiveInt);
 
1;
[download]

Or:

package Person;
use Moo;
use Types::Common::Numeric 'IntRange';
 
has name => (is => 'rw');
has age  => (is => 'rw', isa => IntRange[0,200]);  # 200 is a realisti
+c age limit
 
1;
[download]