Gegenseitige Ausschluss-Typen mittels distributiver bedingter Filterung

type Without<T, U> = { [P in Exclude<keyof T, keyof U>]?: never };
 
type XOR<T, U> = (T | U) extends object
  ? (Without<T, U> & U) | (Without<U, T> & T)
  : T | U;
 
interface CreditCardPayment {
  cardNumber: string;
  cvv: string;
}
 
interface PayPalPayment {
  paypalEmail: string;
  authToken: string;
}
 
type PaymentMethod = XOR<CreditCardPayment, PayPalPayment>;
 
function processPayment(payment: PaymentMethod): void {
  if ('cardNumber' in payment) {
    console.log(`Processing card ${payment.cardNumber}`);
  } else {
    console.log(`Processing PayPal ${payment.paypalEmail}`);
  }
}