compile time function use Nim metaprogramming feature

[mardiyah]

How do we have function on metaprogramming to get a value from an input value, 
just like C++ equivalent one e.g.
    
    
    template<int N>
    constexpr int fac()
    {
       return N∗fac<N−1>();
    }
    
    template<>
    constexpr int fac<1>() {
       return 1;
    }
    
    constexpr int x5 = fac<5>();
    
    
    Run

as on Nim it's macro, thanks in advance