Naming of TypeScript's union and intersection types

Question

I can\'t understand the logic behind the terms union types and intersection types in TypeScript.

Pragmatically, if the properties of different type

Answer 1

I also had the same question and couldn't understand how could it be seen in the opposite way. After reading the answers, I think I could explain it in the linguistic aspect providing different meanings of the two words and giving a room for the opposite naming approaches.

Compare the following meanings of word intersect:

The orbit of this comet intersects the orbit of the Earth.

In this sentence intersect means to cross at a point or set of points. Think of two things having something common (e.g. a point), and otherwise different. That's what is called intersection in math and SQL.

We need to pinpoint the place where maximum achievable conservation intersects with the highest potential financial return.

Here intersect means to come together and have an effect on each other, like two things becoming components of one new cool thing. That's the meaning of the word in TypeScript.

In a similar way you can think of union as an act of joining different things together in a loose sense - that is the meaning of union in math and SQL; but it can mean not just joining but joining together with a common interest or purpose which corresponds to the meaning of union in TypeScript.

Inspired (don't ask me why) by different translations of intersect into Russian: пересекать (also to cross) and скрещивать (also to crossbreed).