Template metaprogramming isn't really suited for this task, the prime sieve here serves only as a proof of concept, meant to show the capabilities of this style. But there are cases where `constexpr` is not applicable, especially when involving type manipulations.

On the other hand, C++ template metaprogramming, as an esolang, is fun to tame and experiment with.

Is there a clearer example where constexpr wouldn't work?

> On the other hand, C++ template metaprogramming, as an esolang, is fun to tame and experiment with.

Is it an esolang at this point? I feel old.