Discriminated unions?

[ivnsch]

I was trying to switch ("match style") over enum cases with fields, but this seems not to be possible. Example (src):

type AppEvent =
  | { kind: "click"; x: number; y: number }
  | { kind: "keypress"; key: string; code: number }
  | { kind: "focus"; element: HTMLElement };

function handleEvent(event: AppEvent) {
  switch (event.kind) {
    case "click":
      // We know it is a mouse click, so we can access `x` and `y` now
      console.log(`Mouse clicked at (${event.x}, ${event.y})`);
      break;
    case "keypress":
      // We know it is a key press, so we can access `key` and `code` now
      console.log(`Key pressed: (key=${event.key}, code=${event.code})`);
      break;
    case "focus":
      // We know it is a focus event, so we can access `element`
      console.log(`Focused element: ${event.element.tagName}`);
      break;
  }
}

Potential feature request, or maybe it's already possible and I'm missing something?