A property where a midpoint always exists (a < c < b). More...

Concept definition

template<typename T>
concept dedekind::order::IsDense = 
    IsTotallyOrdered<T> && !IsDiscrete<T> && requires(const T a, const T b) {
      { (a + b) / T{2} } -> std::convertible_to<T>;
    }

Detailed Description

A property where a midpoint always exists (a < c < b).

The midpoint is computed as (a + b) / T{2} rather than (a + b) / 2 so that the carrier itself supplies the value 2 (via the T{2} structural constructor), rather than relying on mixed-type T-vs-int arithmetic. This matters for variant exact carriers (SignedExtensionalCardinal<>, Rational<...> over such) which do not implicitly inter-operate with literal int — forcing the carrier to construct its own 2 keeps the concept honest across both built-in (int, double) and exact carriers.