package Cat;
use Moo;
use MooX::Types::MooseLike::Base qw(:all);

has name => ( is  => 'ro', isa => Str );

1;

package Litter;
use Moo;
use MooX::Types::MooseLike::Base qw(:all);

has cats => ( is => 'ro', isa => ArrayRef );

1;

package main;

my $cat1 = Cat->new(name=>'Garfield');
my $cat2 = Cat->new(name=>'Felix');

my $litter = Litter->new(cats => [$cat1, $cat2]);

for (@{$litter->cats}) { 
    print $_->name . "\n"
}

##</code><code>##

isa => sub {
  my $param = shift;
  die "<<$param>> must be an array ref" unless ref $param eq 'ARRAY';
  foreach my $element ( @{$param} ) {
    die "<<$element>> isn't a Cat object"
      unless ref $element eq 'Cat';
  }
}

##</code><code>##

die "<<$element>> must have a name attribute"
  unless $element->can('name');

##</code><code>##

isa => ArrayRef[ InstanceOf['Cat'] ]

##</code><code>##

isa => ArrayRef[ HasMethods['name'] ]

##</code><code>##

package Cat;
use Moo;
use MooX::Types::MooseLike::Base 'Str';

has name => ( is => 'ro', isa => Str );

1;

package Litter;
use Moo;
use MooX::Types::MooseLike::Base qw( ArrayRef HasMethods );

has cats => ( is => 'ro', isa => ArrayRef [ HasMethods ['name'] ] );

1;

package main;

my @cat_names = qw( Garfield Felix );

my $litter = Litter->new(
  cats => [ map { Cat->new( name => $_ ) } @cat_names ]
);

print $_->name . "\n" for @{ $litter->cats };