one_of_gen.cpp

template<typename Finalizer, typename Generator, typename... Generators>
auto one_of_gen(Finalizer finalizer, Generator head, Generators... tail)
{
   using Out = decltype(finalizer(head(std::declval<std::mt19937&>())));
   std::vector<std::function<Out(std::mt19937&)>> gens{
      transform_gen(finalizer, head),
      transform_gen(finalizer, tail)...
   };

   return [=](std::mt19937& bit_gen)
   {
      std::uniform_int_distribution<int> distribution(0, gens.size() - 1);
      return gens[distribution(bit_gen)](bit_gen);
   };
}