use v5.16;

package Local::App {
	use Zydeco;
	use List::Util 'sum';

	class Calc {
		method r ( $n ) = 1/$n;
		method a ( PositiveInt $n ) = 1 + $self->r($n);
		method S ( PositiveInt $n ) = sum( map $self->a($_), 1 .. $n );
		
		class +Rational {
			use Math::BigRat;
			method r ( $n ) = Math::BigRat->new("1/$n");
		}
	}
}

my $calc = Local::App->new_calc_rational;
say $calc->S(15);