Thinking of TypeScript as a functional language that operates on sets

George

Future

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Think of TypeScript's type system as a functional language that operates over sets. Types can be considered as sets of literals they can construct. By resolving types into sets, intersections and unions become clearer. Primitives in TypeScript allow introspection and transformation of these sets. Mapped types and recursive logic enable advanced type manipulations. Viewing TypeScript through this lens helps to understand and utilize its advanced features better.

A different way to think about TypeScript

This is a nice article, but I felt that the difference about intersect (&amp;) and union (|) is not very clear… In case others thought as well, this is from the oficial Typescript doc:
<blockquote>
A union type describes a value that can be one of several types. We use the vertical bar (|) to separate each type, so number | string | boolean is the type of a value that can be a number, a string, or a boolean.
</blockquote>
<blockquote>
An intersection type combines multiple types into one. This allows you to add together existing types to get a single type that has all the features you need. For example, Person &amp; Serializable &amp; Loggable is a Person and Serializable and Loggable. That means an object of this type will have all members of all three types.
</blockquote>