2.ts

interface FruitMap {
  'Apple': AppleFruit;
  'Banana': BananaFruit;
}

type FruitName = keyof FruitMap;

type Fruit = FruitMap[FruitName]

interface FruitBase<Type extends FruitName> {
  type: Type
}

interface AppleFruit extends FruitBase<'Apple'> {
  sliced: boolean;
  peeled: boolean;
}

interface BananaFruit extends FruitBase<'Banana'> {
  color: 'yellow' | 'green';
}

function createFruitOf<T extends FruitName>(type: T): FruitMap[T] {
  if (type === 'Apple') {
    const apple: AppleFruit = {
      peeled: false,
      sliced: false,
      type: 'Apple',
    };
    return apple as any;
  }

  if (type === 'Banana') {
    const banana: BananaFruit = {
      color: 'green',
      type: 'Banana',
    };
    return banana as any;
  }

  throw new Error(`Unknown type "${type}"`);
}

const apple = createFruitOf('Apple');
const banana = createFruitOf('Banana');