[mandarax8]

Because the only way to do metaprogramming in C++ is via the type system. Thismakes it so you need to implement 'functions' as types.

[nly]

While this is true, you can do so much these days with functions with 'auto' return types (function templates), constexpr functions/lambdas and "if constexpr"

[jstimpfle]

What does that mean, and is it even true, given template value parameters or constexpr for example?

[fc417fc802]

Sure, auto constexpr stuff can express some things. Not most things though, at least in my experience. Perhaps a skill issue on my part. Or things might have changed again. I'm "still" using C++20 after all.

> What does that mean

Have you ever noticed that the (compile time) "rules" for interacting with templated functions are somewhat different from those of non-templated functions? I don't know if "functions as types" is entirely fair but there is definitely some weirdness.