The following program shows how a dependency handler might look in Perl 6. It showcases custom constructors, private and public attributes, methods and various aspects of signatures. It's not very much code, and yet the result is interesting and, at times, useful.

    class Task {
        has      &!callback;
        has Task @!dependencies;
        has Bool $.done;

        method new(&callback, Task *@dependencies) {
            return self.bless(*, :&callback, :@dependencies);
        }

        method add-dependency(Task $dependency) {
            push @!dependencies, $dependency;
        }

        method perform() {
            unless $!done {
                .perform() for @!dependencies;
                &!callback();
                $!done = True;
            }
        }
    }

    my $eat =
        Task.new({ say 'eating dinner. NOM!' },
            Task.new({ say 'making dinner' },
                Task.new({ say 'buying food' },
                    Task.new({ say 'making some money' }),
                    Task.new({ say 'going to the store' })
                ),
                Task.new({ say 'cleaning kitchen' })
            )
        );

    $eat.perform();