I was more pointing in the direction of "sets" in general. Sets as such are mathematical entities. (Isn't there even a category of sets where sets are objects)

I was more pointing in the direction of "sets" in general. Sets as such are mathematical entities. (Isn't there even a category of sets where sets are objects)? But apparently not everybody agree as this got down votes; or someone don't see the parallels between sets and types? Strange.