suspend.ts

type SuspendStatus = "pending" | "success" | "error";
export function suspend<T>(promise: Promise<T>) {
    let result: T;
    let error: Error;
    let status: SuspendStatus = "pending";

    let suspender = promise.then(
        (r) => {
            status = "success";
            result = r;
        },
        (e) => {
            status = "error";
            error = e;
        },
    );

    return {
        read() {
            switch (status) {
                case "pending":
                    throw suspender;
                case "error":
                    throw error;
                default:
                    return result;
            }
        },
    };
}