#define BOOST_HANA_CONFIG_ENABLE_STRING_UDL


namespace hana = boost::hana;

using namespace hana::literals;

using hana::make_map, hana::insert, hana::make_pair, hana::_, hana::always, hana::traits::is_same, hana::decltype_;


int main() {
 auto foo = insert(insert(make_map(), make_pair("a"_s, _ + 1)), make_pair("b"_s, always("co")));
 
 
 auto call = [=](auto name, auto ... args) {
   return foo[name](args...);
 };
 
 auto reta = call("a"_s, 1);
 auto retb = call("b"_s);
 
 static_assert(is_same(decltype_(reta), decltype_(2)));
 static_assert(is_same(decltype_(retb), hana::type_c<const char *>));
}