gistfile1.PL

#!perl -w
use Any::Moose;
use Any::Moose '::Util::TypeConstraints';
use Math::BigInt;

subtype 'BigInt', as 'Math::BigInt';
coerce 'BigInt',
    from 'Int', via { Math::BigInt->new($_) };

has value => (
    is => "rw",
    isa => "BigInt",
    coerce => 1,
);
warn __PACKAGE__->new(value => "1" . ("0"x100));
warn __PACKAGE__->new(value => 10e100);
__END__