Namaran

visit_pair.cpp

#include <iostream>
#include <variant>

template <class... Fs>
struct overloaded : Fs... { using Fs::operator()...; };
template <class... Fs>
overloaded(Fs...) -> overloaded<Fs...>;

int main() {
    std::variant<int, char> a = 3;
    std::variant<int, char> b = 'A';

    int result = std::visit(overloaded{
        [](int x, int y) { return x + y; },
        [](int x, char y) { return x * y; },
        [](char x, int y) { return x - y; },
        [](char x, char y) { return x + y; },
    }, a, b);

    std::cout << result << '\n';
}