Enums

An enum defines a type with a fixed set of variants:

enum State {
    Pending,
    Running,
    Finished,
}

var state = State.Pending;

Variants are accessed through the enum type.

Compare enum values

if state == State.Pending {
    state = State.Running;
}

if state != State.Finished {
    println("work remains");
}

Explicit values

Variants may specify integer values:

enum ExitCode {
    Success = 0,
    InvalidInput = 2,
    Unavailable = 69,
}

Convert an enum value explicitly when an integer is required:

var code: Int = ExitCode.InvalidInput as Int;

C-compatible enums

Use @repr("C") for an enum passed through a C ABI:

@repr("C")
enum Direction {
    Left,
    Right,
}

Match the values and representation expected by the C declaration.

Enum variants can also carry values. That separate feature is covered in Tagged unions. Error enums are covered in Error handling.