◆ is_stan_scalar_or_eigen

template<typename T >

using stan::is_stan_scalar_or_eigen = typedef bool_constant<is_stan_scalar<std::decay_t<T> >::value || is_eigen<std::decay_t<T> >::value>

Extends std::true_type if all the provided types are either a Stan Scalar type or a type inheriting from EigenBase.