use strict;
use warnings;

{
	package Cat;
	use Moose;
	
	has name => (
		is  => 'ro',
		isa => 'Str',
	);
	
	__PACKAGE__->meta->make_immutable;
}

{
	package Litter;
	use Moose;
	
	has cats => (
		is  => 'ro',
		isa => 'ArrayRef[Cat]',
	);
	
	__PACKAGE__->meta->make_immutable;
}

my $cat1   = Cat->new(name=>'Garfield');
my $cat2   = Cat->new(name=>'Felix');
my $litter = Litter->new(cats => [$cat1, $cat2, 1]);

##</code><code>##

use strict;
use warnings;

{
	package Cat;
	use Moo;
	use Types::Standard -types;
	
	has name => (
		is  => 'ro',
		isa => Str,
	);
}

{
	package Litter;
	use Moo;
	use Types::Standard -types;
	
	has cats => (
		is  => 'ro',
		isa => ArrayRef[InstanceOf['Cat']],
	);
}

my $cat1   = Cat->new(name=>'Garfield');
my $cat2   = Cat->new(name=>'Felix');
my $litter = Litter->new(cats => [$cat1, $cat2, 1]);

##</code><code>##

use Moops;

class Cat :ro {
	has name => (isa => Str);
}

class Litter :ro {
	has cats => (isa => ArrayRef[InstanceOf['Cat']]);
}

my $cat1   = Cat->new(name=>'Garfield');
my $cat2   = Cat->new(name=>'Felix');
my $litter = Litter->new(cats => [$cat1, $cat2, 1]);

##</code><code>##

use strict;
use warnings;
use Types::Standard -types;
use MooX::Struct Cat    => ['$name'];
use MooX::Struct Litter => ['@cats' => [ isa => ArrayRef[InstanceOf[Cat]] ]];

my $cat1   = Cat->new(name=>'Garfield');
my $cat2   = Cat->new(name=>'Felix');
my $litter = Litter->new(cats => [$cat1, $cat2, 1]);

##</code><code>##

use strict;
use warnings;
use MooseX::Struct;

immutable struct Cat => (
	name => { isa => 'Str' },
);

immutable struct Litter => (
	cats => { isa => 'ArrayRef[Cat]' },
);

my $cat1   = Cat->new(name=>'Garfield');
my $cat2   = Cat->new(name=>'Felix');
my $litter = Litter->new(cats => [$cat1, $cat2, 1]);