Anonymous Recursion in C++

anonymous_rec.cpp

// $ g++-4.9 -std=c++1y anonymous_rec.cpp
#include <iostream>

template<typename Func>
struct fixed {
    Func f;

    template<typename... Args>
    auto operator()(Args... args) {
        return f(fix(f), args...);
    }
};

template<typename Func>
fixed<Func> fix(Func f) {
    return { f };
}

int main()
{
    // fib(4) => 5
    std::cout << (fix([](auto self, int n) -> int {
        return n <= 1 ? 1 : self(n-1) + self(n-2);
    }))(4) << std::endl;

    // gcd(15, 9) => 3
    std::cout << (fix([](auto self, int a, int b) -> int {
        return b == 0 ? a : self(b, a % b);
    }))(15, 9) << std::endl;
    return 0;
}