C++11: Compile Time Calculation of Array

Question

Suppose I have some constexpr function f:

constexpr int f(int x) { ... }

And I have some const int N known at compile time:

Either<

Answer 1

Here's a more concise answer where you explicitly declare the elements in the original sequence.

#include 

constexpr int f(int i) { return 2 * i; }

template 
struct sequence
{
    using result = sequence;
    static std::array apply() { return {{Ts...}}; }
};

using v1 = sequence<1, 2, 3, 4>;
using v2 = typename v1::result;

int main()
{
    auto x = v2::apply();
    return 0;
}