Verwaltung von asynchronem Zustand mit diskriminierten Union-Typen

type AsyncState<T> =
  | { status: 'idle' }
  | { status: 'loading' }
  | { status: 'success'; data: T }
  | { status: 'error'; error: Error };
 
function renderState<T>(state: AsyncState<T>): string {
  switch (state.status) {
    case 'idle':
      return 'Waiting to start...';
    case 'loading':
      return 'Fetching data...';
    case 'success':
      return `Data loaded: ${JSON.stringify(state.data)}`;
    case 'error':
      return `Error occurred: ${state.error.message}`;
  }
}