Explizite In/Out-Varianz-Annotationen für typsichere Subtyp-Kompatibilität

type Animal = { name: string };
type Dog = Animal & { breed: string };
 
interface Container<out T> {
  get(): T;
}
 
interface Writer<in T> {
  put(item: T): void;
}
 
function processProducer(c: Container<Animal>): string {
  return c.get().name;
}
 
const dogContainer: Container<Dog> = { get: () => ({ name: "Rex", breed: "Shepherd" }) };
const name = processProducer(dogContainer);