dedekind::category::IsBinaryRelation Concept Reference

A type R is a binary relation A × B → bool if it is callable on A and B and yields a boolean. More...

Concept definition

template<typename R, typename A, typename B, typename Ω bool>
concept dedekind::category::IsBinaryRelation = 
    IsTruthObject<Ω> && requires(R const& r, A const& a, B const& b) {
      { r(a, b) } -> std::convertible_to<Ω>;
    }

Detailed Description

A type R is a binary relation A × B → bool if it is callable on A and B and yields a boolean.

Callable-indicator reading of R ⊆ A × B (the predicate is the membership-of-pair indicator). Sibling to the value-level relational::Relation<T1, T2, L, P> alias, which models the relation as a Set of pairs. The two readings are isomorphic.