Enums

User-defined enums lower to tagged tables. This is the language page; for a worked phase machine see State machines with enums.

Shapes

Rust	Lua
Color::Red	{ tag = "Red" }
Msg::Move(x, y)	{ tag = "Move", _1 = x, _2 = y }
Msg::Move { x, y }	{ tag = "Move", x = x, y = y }

enum Msg {
    Quit,
    Move(i64, i64),
    Say { text: String },
}

impl Msg {
    fn is_quit(&self) -> bool {
        matches!(self, Msg::Quit)
    }
}

Inherent methods share a table with unit variant constants, like structs.

match

match msg {
    Msg::Quit => {}
    Msg::Move(x, y) => println!("{x},{y}"),
    Msg::Say { text } => println!("{text}"),
}

Supported patterns include unit / tuple / named variants, guards, and or-patterns. matches!(expr, pat) / matches!(expr, pat if guard) is supported and desugars to a value match that yields true / false. Full pattern rules: Supported Rust -> match.

Not the same as API unions

Factorio literal unions (GuiDirection, …) stay Lua strings. Your enums are tagged tables. Prefer Identification constructors such as ForceID::Name("enemy") (they lower to the Factorio payload) - see API types.