Move Fast And Build Things
A product-type is a generalized notion of having a bunch of things at the same physical locality (or proximity) – this and [also] that. This is what molecules are. A sum-type is a generalized abstract notion of having this-or-that (either-this-or-that, and NOT both). This is, among other things, a “fork” on a path – never both can be taken (except when backtracking). These notions are enough for everything and they are our basic building blocks. ...