gistfile1.pl

package A;
use Moo;
use Mouse::Util::TypeConstraints ();

sub mouse_isa ($) {
    my $t = Mouse::Util::TypeConstraints::find_or_create_isa_type_constraint($_[0]);
    return sub { $t->assert_valid($_[0]) };
}

has foo => (
    is  => 'rw',
    isa => mouse_isa('Int'),
);

has ua => (
    is  => 'rw',
    isa => mouse_isa('LWP::UserAgent'),
);