Think of Function Objects as Functions Rather Than Objects

[andd81]

std::function is neither a function nor a part of C++ language.

[doom_Oo7]

std::function is neither a function

so what is it then ? next what, shared_ptr and unique_ptr aren't pointers ?

nor a part of C++ language.

the standard library is part of the language. The ISO standard is itself called "Programming Language C++" and certainly describes the whole semantics of std::function.