Enums

An enum, also known as a sum type, is a type that consists of several variants where each variant is named and has a type.

Let's take a look at an example where we define an enum called Color with a few color variations.

{{#include ../../../code/language/built-ins/enums/src/basic_enum.sw:definition}}

We begin by using the enum keyword followed by the name for our enumeration. The variants are contained inside {} and they are ordered sequentially from top to bottom. Each variant has a name, such as the first Blue variant, and a type, which in this case is the unit type () for all variants.

The unit type is a type that does not contain any data however any type can be used.

{{#include ../../../code/language/built-ins/enums/src/basic_enum.sw:init}}

Enums of Structs

In order to demonstrate more complex data types we can define a struct and assign that struct as a data type for any of an enum's variants.

Here we have a struct Item and an enum MyEnum. The enum has one variant by the name Product and its type is declared to the right of : which in this case is our struct Item.

{{#include ../../../code/language/built-ins/enums/src/enum_of_structs.sw:content}}

Enums of Enums

Similar to structs we can use other enums as types for our variants.

{{#include ../../../code/language/built-ins/enums/src/enum_of_enums.sw:content}}