Structs

Karina uses Structs as primary data structures, allowing you to define custom data types with named fields. They are for now similar to Java classes, but with a more lightweight syntax.

Like in Java, struts are reference types, meaning they are stored in the heap and always passed by reference.

Structs define the following:

• Constants
• Fields
• Methods & Constructors
• Interfaces

Constants

The first thing that can be defined in a struct are constants. Constants are static fields that are immutable and can be used in the struct definition. They are defined using the const keyword.

struct Person {
    const MAX_AGE: int = 100
    const MIN_AGE: int = 0

    //...
}

Fields

Methods & Constructors

struct Person {
    name: mut string
    
    fn setName(self, name: string) {
        self.name = name
    }

}

Instance methods are defined using self as the first parameter.

Every method without self is a static method.

struct Person {
    name: string
    age: int

    fn default() -> Person = Person { name: "Karina", age: 25 }
}
let default_person = Person::default()

Each structs has a default constructor, for initializing all fields.

struct Person {
    name: string
    age: int
}
let person = Person {
    name: "Karina",
    age: 3
}

You can also define your own constructors

struct Person {
    name: string
    age: mut int
    fn (self, name: string) {
        self.name = name
        self.age = 0
    }
}
let person = Person {
    name: "Karina"
}
person.age = 4

Interfaces

Interfaces are the last parameter in the struct definition. They behave exactly like in Java

struct Person {
    name: string
    age: int

    impl Serializable 

    impl AutoCloseable {
        fn close(self) {
            // ...
        }
    }
}