Enums

Enums represent a fixed set of distinct constant values. In Autolang, enums can declare methods and dispatch states cleanly with the when expression.

Declaring Enums & Methods

Declare enum constants separated by commas, terminated with a semicolon if methods are declared inside the enum. Inside an enum method, this refers to the active enum constant.

enum OrderStatus {
    PENDING, PROCESSING, SHIPPED, DELIVERED, CANCELLED;

    fun isTerminal(): Bool = when (this) {
        DELIVERED -> true
        CANCELLED -> true
        else      -> false
    }

    fun label(): String = when (this) {
        PENDING    -> "Order Pending"
        PROCESSING -> "Processing Warehouse"
        SHIPPED    -> "In Transit"
        DELIVERED  -> "Delivered Successfully"
        CANCELLED  -> "Order Cancelled"
        else       -> "Unknown"
    }
}

val currentStatus = OrderStatus.PROCESSING
println("Current label: " + currentStatus.label())
println("Is terminal state? " + currentStatus.isTerminal())

Comparing Enum Values

Enum values are compared directly with == and !=. They can also be passed into functions or stored in collections.

enum OrderStatus {
    PENDING, PROCESSING, SHIPPED, DELIVERED, CANCELLED;
}
val requiredState = OrderStatus.SHIPPED
val actualState = OrderStatus.SHIPPED

println("States match: " + (requiredState == actualState)) // true
println("Not pending: " + (requiredState != OrderStatus.PENDING)) // true

val allowedTransitions = [OrderStatus.PENDING, OrderStatus.PROCESSING]
if (OrderStatus.PENDING in allowedTransitions) {
    println("Status eligible for modification")
}