2.1 Interfaces

Objects have types which are called interfaces. You can define an interface like this:

  interface Person {
    get_name : 1 -> string;
    get_age : 1 -> int;
    set_age : int -> 0;
  }

An interface is nothing more than alias for a record type. In particular the above is equivalent to

  typedef Person2 = (
    get_name : 1 -> string,
    get_age : 1 -> int,
    set_age : int -> 0
  );

Now, we can define a person with the interface:

  object person (name:string, var age: int) implements Person = {
    method fun get_name () => name; 
    method fun get_age () => age; 
    method proc set_age (x:int) { age = x; }
  };

Of course interfaces can be extended:

  interface WorkingPerson extends Person { 
    get_occupation: 1 -> string; 
  }