export class Err<T, U> {
	#inner: T;
	#exception?: U;

	constructor(inner: T, exception?: U) {
		this.#inner = inner;
		this.#exception = exception;
	}

	get inner(): T {
		return this.#inner;
	}

	get exception(): U | undefined {
		return this.#exception;
	}

	/**
	 * Type guard for `Ok`
	 * @returns `true` if `Ok`; `false` if `Err`
	 */
	isOk(): false {
		return false;
	}

	/**
	 * Type guard for `Err`
	 * @returns `true` if `Err`; `false` if `Ok`
	 */
	isErr(): this is Err<T, U> {
		return true;
	}

	/**
	 * Create an `Err`
	 * @param inner
	 * @returns `Err(inner)`
	 */
	static new<E, F>(inner: E, exception: F): Err<E, F> {
		return new Err<E, F>(inner, exception);
	}
}