Compound data

Here you will learn two fundamental "compound" data types in East - structs and variants.

Structs (or "structures") allow you to create objects out of multiple pieces of data, organized into named fields of given types. They represent an object that has some data AND some other data. For a real-world example, a car might consist of an engine AND some wheels. In East, a struct might contain both an integer AND a string.

Variants (or "sum types") are used when an object could be one of multiple different "kinds" of thing, organized into named cases of different types. A variant represents an object that is some thing OR some other thing. For a real-world example, a vehicle might be a car OR a motorcycle. In East, a variant might contain either an integer OR a string.

Structs and variants complement each other, and each is a kind of logical "dual" to the other (just as AND and OR are logically dual to each other). Using these two primitives it is possible to construct complex structured data for just about any situation imaginable. You will conclude with a segment on how different types in East are related via subtyping, a situation that occurs due to the inclusion of both flow typing and variants in East.