The Base and Core modules are essential to the Julia run time… but how are the different? e.g. I can see Complex being defined in Base but Int types are defined in Core…
Further, it seems that everything is “exposed” in Base:
Core is what’s defined in C as the very core of the language. There is very little there. It’s used to bootstrap the rest of the language by gradually defining more and more of Base in terms of what was defined before. Core is kind of an implementation detail that users should never need to interact with.