#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_, hana::make_set, hana::type_c, hana::find, hana::nothing;

struct a {};
struct b {};
struct c {};

auto allow_types = make_set(type_c<a>, type_c<b>);

template<typename T> concept inmap = requires {
 requires bool(find(allow_types, type_c<T>) != nothing);
};


void f(inmap auto) {
 fprintf(stderr, "inmap -> %s\n", __PRETTY_FUNCTION__);  
}

void f(auto) {
 fprintf(stderr, "none -> %s\n", __PRETTY_FUNCTION__);
}



int main() {
 inmap auto x = b{};
//   inmap auto x = c{};
 f(a{});
 f(b{});
 f(c{});
}