Factorial macro example in C++23 metaprogramming,
#include <iostream>
consteval long factorial (int n) {
if (n == 0) return 1;
return n * factorial(n - 1);
}
int main() {
std::cout << factorial(7) << std::endl;
}
Exercise for the reader if using VC++ or clang/ninja, use
import std instead.
-- https://godbolt.org/z/TWe11hM6j
Nicely put 5040 in ESI register at compile time.
Granted, C++ isn't Lisp, but already has quite a room for creativity at compile time, and C++26 might finally have compile time reflection as well.
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