Function memoize_binary

include_all_in_one/include/fplus/fplus.hpp:1740–1750

        typename std::remove_reference<typename std::remove_const<FIn2>::type>::type>,
    typename MemoMap = std::unordered_map<ParamPair, FOut>>
std::function<FOut(FIn1, FIn2)> memoize_binary(F f)
{
    const auto unary_f = [f](const ParamPair& params) -> FOut {
        return internal::invoke(f, params.first, params.second);
    };
    auto unary_f_memoized = memoize<decltype(unary_f),
        ParamPair, FOut, std::map<ParamPair, FOut>>(unary_f);
    return [unary_f_memoized](FIn1 a, FIn2 b) mutable -> FOut {
        return unary_f_memoized(std::make_pair(a, b));
    };
}

// API search type: constructor_as_function : a -> b
// struct foo