Traits and Enums

A trait is a contract specifying what bindings an implementing class must provide. A class implements a trait with : TraitName and marks the overriding members with override:

trait Faculty {
  let firstName : string
  let lastName : string
  let age : i32

  let sayHello()
}

class Teacher(
  override firstName: string,
  override lastName: string,
  override age: int
) : Faculty {
  override sayHello() {
    print("Hello ${firstName} ${lastName}. I am a teacher.")
  }
}

Enums

Enums describe a fixed set of related values, where each case can carry its own data. match is the idiomatic way to branch on which case you have:

trait Person
enum People : Person {
  # object represents a single instance member of the enumeration.
  object Unnamed(let name = "unknown"),

  class Teacher(override name : string),
  class Student(override name : string)
}

let process(person: People) {
  match(person) {
    People.Teacher -> println("Teacher: ${person.name}")
    People.Student -> println("Student: ${person.name}")
    else -> raise RuntimeException("Unhandled person type")
  }
}

Enums​

Enums