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Comment by codedokode | Hacker News Reader

By the way I looked through the code, and had to read about metaprogramming in C++. I wonder why is it so complicated? For example, why constraints like std::is_integral are represented by structs. Doesn't make much sense to me. A function wouldn't be better here?

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

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"

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

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.

Practically, it's all through this `type_traits` header that (often) end up in unreadable messes. It's all possible because of the catchy acronym SFINAE. It doesn't make much sense to me either, so I avoid it :)

https://en.cppreference.com/w/cpp/language/sfinae

You don't really need to use sfinae anymore, concepts are cleaner and easier to follow, also this library appears to use concepts

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