# ~/monks/1209129.t package MyTypes { use parent 'Type::Library'; use Type::Utils; use Types::Standard qw/ ArrayRef Dict Enum Str StrMatch /; my $MyArray = Type::Tiny->new( as => 'ArrayRef', name => 'ClientArray', constraint => sub { scalar @{ $_ } == 2 }, ); declare MyType => as Dict[ method => Enum['xxx'], backend => Dict[ client => StrMatch[qr/\d{3}/], pw => Str, ], clientArr => $MyArray, ]; # If you want to be able to use the new type independently by name: __PACKAGE__->meta->add_type($MyArray); __PACKAGE__->meta->make_immutable; }; package main { use Test::Most; use JSON; # normally, load as normal with `use MyTypes '+MyType'` MyTypes->import(qw/ +MyType /); while ( ) { my ( $label, $json ) = split / => /; chomp $json; my $data = from_json $json; if ( $. == 1 ) { ok eval { assert_MyType( $data ); 1 }, $label; } else { ok ! eval { assert_MyType( $data ); 1 }, $label; } } done_testing; }; __END__ Valid data => {"method":"xxx","backend":{"client":"mytest009","pw":"sdkjfhsfjhKJH87"},"clientArr":[{"num":"1"},{"num":"2"}]} Unknown key => {"method":"xxx","backend":{"client":"mytest009","pw":"sdkjfhsfjhKJH87"},"clientArr":[{"num":"1"},{"num":"2"}],"blah":"123"} Failed regexp => {"method":"xxx","backend":{"client":"mytest09","pw":"sdkjfhsfjhKJH87"},"clientArr":[{"num":"1"},{"num":"2"}]} Not an array => {"method":"xxx","backend":{"client":"mytest009","pw":"sdkjfhsfjhKJH87"},"clientArr":{"foo":{"num":"1"},"bar":{"num":"2"}}} Array too long => {"method":"xxx","backend":{"client":"mytest009","pw":"sdkjfhsfjhKJH87"},"clientArr":[{"num":"1"},{"num":"2"},{"num":"3"}]}