I think it's questionable what the sentences that use this term are really trying to say. As in, does the use of "functions" in those sentences actually mean "functions" in the core language sense? Perhaps. In which case, the sentence means that, with the wrapper functionality, core language functions act as, and can be made into, callable objects.

Agreed this needs fixing.

I think it's questionable what the sentences that use this term are really trying to say. As in, does the use of "functions" in those sentences actually mean "functions" in the core language sense?

Yes.

Perhaps. In which case, the sentence means that, with the wrapper functionality, core language functions act as, and can be made into, callable objects.

Right, which is true. ("Callable object" is defined by the library). But you can also turn a function into a callable object just by taking its address, as a function pointer is a callable object.

"First-class object" is a commonly used term in the field of programming languages, but we can remove it if it's a problem. The end of that sentence isn't adding anything. The point of move_only_function is type erasure, to hide the differences between different types of callable object with a given call signature. Creating first-class objects is not the main advantage.

"First-class object" is a commonly used term in the field of programming languages, but we can remove it if it's a problem. The end of that sentence isn't adding anything. The point of move_only_function is type erasure, to hide the differences between different types of callable object with a given call signature. Creating first-class objects is not the main advantage.

I'm not a fan of this alleged term at all. It ranks right up there with "safe" as a term that's unhelpful and nebulous and could easiy be replaced by a more appropriate term. How is a a first-class object different from any other kind of object? What other classes are there? Why not just "object"?

I would not shed a tear over losing this sentence entirely.

Obviously, a first-class object is an object that has bells, whistles, and skids, so let's get rid of that phrase.

It's a term that has its own Wikipedia page.

https://en.m.wikipedia.org/wiki/First-class_citizen

And given the existing but sightly different meaning of "object" in C++, maybe saying first-class citizen would have been better here. But removing it doesn't decrease the usefulness or correctness of those paragraphs so I agree with removing it.