The Enum Pattern in Luau

Programs are full of values drawn from a small, fixed set: an order is pending, shipped or delivered; a player faces up, down, left or right. Many languages have an enum keyword for this. Luau does not — and it doesn't need one, because two tools you already own cover the job.

Pattern 1: the constant table. A plain table maps meaningful names to values, replacing "magic numbers" scattered through the code:

local Status = {
    Pending = 1,
    Active = 2,
    Done = 3,
}

print(Status.Active) -- 2

This is a real runtime value: you can read Status.Active, compare against it, and pass it around — just like the tables you've used all along.

Pattern 2: the literal union. A type made of exact string values, using the literal types you met in the unions chapter:

type Color = "red" | "green" | "blue"
local favorite: Color = "green" -- ✓
local oops: Color = "yellow"    -- ✗ type error

The union exists only for the checker — zero runtime cost — but it guarantees a variable can hold nothing outside the set. The two patterns complement each other: the table gives you runtime values under one name; the union gives you a compile-time guarantee. Later in this chapter you'll also meet table.freeze, which protects a constant table from being modified at runtime.