通过递归类型减少TypeScript类型的可能性

type BinaryTree<T> = {
  value: T;
  left?: BinaryTree<T>;
  right?: BinaryTree<T>;
};

type Expression =
  | number
  | { type: 'add'; left: Expression; right: Expression }
  | { type: 'subtract'; left: Expression; right: Expression }
  | { type: 'multiply'; left: Expression; right: Expression }
  | { type: 'divide'; left: Expression; right: Expression };

type JSONValue = string | number | boolean | null | JSONObject | JSONArray;
interface JSONObject {
  [key: string]: JSONValue;
}
interface JSONArray extends Array<JSONValue> {}

function parseJSON<T extends JSONValue>(json: string): T {
  return JSON.parse(json) as T;
}

function toJSON(value: JSONValue): string {
  return JSON.stringify(value);
}