I think that's it in a nutshell. You can't evaluate everything at compile time, even when you could theoretically. So you need some way to mark the subset of pu

I think that's it in a nutshell. You can't evaluate everything at compile time, even when you could theoretically. So you need some way to mark the subset of pure functions that can be evaluated at compile time, which is what const fn does. That way if a const fn only calls other const functions you know you can evaluate it. It's a convenient way of tagging functions.