Objects

Draft uses records (also called structs) to define custom data structures.

Defining Records

record User
    name: String
    age: Int
    email: String
fin record.

Creating Instances

@user = User {
    name: "Alice",
    age: 30,
    email: "alice@example.com"
}

Accessing Fields

Use # for member access:

write(@user#name)   @// "Alice"
write(@user#age)    @// 30

Mutable Fields

Records are immutable by default. Use mut for mutable instances:

mut @user = User {
    name: "Alice",
    age: 30,
    email: "alice@example.com"
}

@user#age = 31  @// OK: user is mutable

Record Actions

Define actions on records:

record User
    name: String
    age: Int
    email: String
fin record.

impl User
    action greet(@self: User) -> String
        return "Hello, I'm " + @self#name
    fin action.

    action is_adult(@self: User) -> Boolean
        return @self#age >= 18
    fin action.

    action birthday(@self: mut User)
        @self#age = @self#age + 1
    fin action.
fin impl.

@user = User { name: "Alice", age: 30, email: "alice@example.com" }
write(@user#greet())       @// "Hello, I'm Alice"
write(@user#is_adult())    @// true

Constructor Pattern

Create a constructor function:

record User
    name: String
    age: Int
    email: String
fin record.

action new_user(@name: String, @age: Int, @email: String) -> User
    return User {
        name: @name,
        age: @age,
        email: @email
    }
fin action.

@user = new_user("Alice", 30, "alice@example.com")

Default Values

Provide default values for fields:

record Config
    host: String = "localhost"
    port: Int = 8080
    debug: Boolean = false
fin record.

@config = Config {}  @// Uses all defaults
@custom = Config { host: "0.0.0.0", port: 3000 }

Generic Records

Records can be generic:

record Pair<A, B>
    first: A
    second: B
fin record.

@pair = Pair<Int, String> { first: 1, second: "one" }

Record Inheritance

Records can extend other records:

record Shape
    x: Float
    y: Float
fin record.

record Circle
    extends Shape
    radius: Float
fin record.

@circle = Circle { x: 0.0, y: 0.0, radius: 5.0 }

Destructuring Records

{@name, @age} = @user
@// name = "Alice", age = 30

Record Equality

Records implement structural equality:

@a = User { name: "Alice", age: 30, email: "a@b.com" }
@b = User { name: "Alice", age: 30, email: "a@b.com" }
@a == @b  @// true

Record Cloning

@original = User { name: "Alice", age: 30, email: "a@b.com" }
@copy = @original#clone()

Singleton Objects

For singleton patterns:

singleton Logger
    action log(@message: String)
        write("[LOG] " + @message)
    fin action.
fin singleton.

@Logger#log("Hello")

Type Aliases for Records

type Point = { x: Float, y: Float }

Next Steps

Continue to Enums for enumerated types.