BEGIN { use MooseX::Declare; class Foo { use feature qw(say); use Data::Dumper; use MooseX::MultiMethods; use MooseX::Types -declare => [qw(Bar MyStr MyNum)]; use MooseX::Types::Moose qw(Str Num); use MooseX::Types::Structured qw(Dict); BEGIN { subtype MyStr, as Str; subtype MyNum, as Num; subtype Bar, as Dict[ string => MyStr, number => MyNum, ], message { 'Invalid Foo struct' }; }; multi method baz(Bar $barrr) { say'Bar'; say Dumper $barrr } multi method baz(Str $string) { say 'Str'; say Dumper $string; } } } no Moose; no MooseX::Declare; 1; package main; my $foo = Foo->new; $foo->baz( { string => 'hello', number => 1.00, } ); $foo->baz( 'hello world' )