Classes and Objects

A class defines a data structure you can instantiate:

class MyClass

let instance = MyClass()

Constructor parameters as fields

Marking a constructor parameter with let or var makes it a stored field — immutable or mutable, respectively. This is a very common pattern in Nylon:

class Person(
  let firstName: string,
  let lastName: string,
  let age: i32
) {
  let sayHello() {
    print("Hello ${firstName} ${lastName}")
  }
}

entrypoint main() {
  let person = Person("firstName", "lastName", 25)
  person.sayHello()
}

If you need more control over construction, you can write the constructor explicitly:

class Person {
  let first : string
  let last : string
  let age : int

  public operator new(first: string, last: string, age: int) {
    self.first = first
    self.last = last
    self.age = age
  }
}

Data classes

Marking a class data automatically generates equality and hashing, so instances can be used as map keys:

data class Person(firstName: string, lastName: string)

Singletons

object Singleton {
  let function() { ... }
}