function composition in C++ / C++11

Question

I am currently coding some cryptographic algorithms in C++11 that require a lot of function compositions. There are 2 types of composition I have to deal with :

Answer 1

Here is a simple c++14 solution (it may probably be re-written to c++11):

#include 

// base condition
template 
auto compose(F&& f)
{
    return [a = std::move(f)](auto&&... args){
        return a(std::move(args)...);
    };
}

// recursive composition
// from compose(a, b, c...) to compose(ab, c...)
template 
auto compose(F1&& f1, F2&& f2, Fs&&... fs)
{
    return compose(
        [first = std::move(f1), second = std::move(f2)]
        (auto&&... args){
            return second(first(std::move(args)...));
        },
        std::move(fs)...
    );
}

Possible usage:

int main()
{
const auto f = compose(
  [](const auto n){return n * n;},
  [](const auto n){return n + 2;},
  [](const auto n){return n + 2;}
);
std::cout << f(10) << std::endl; // outputs 104
}

Here is a link to the repo with a few more examples: https://github.com/nestoroprysk/FunctionComposition