/**
 * Union type to wrap the original type T and allow Errors additionally
 */
export declare type Try<T, E extends Error = Error> = [T, null] | [null, E];
/**
 * tc wraps code that throws, and returns the result OR the error thrown
 *
 * it imitates the concept (though it's not a monad) of scala.util.Try — but try is a reserved keyword, so it's called tc
 */
export declare function tc<T, E extends Error = Error>(asyncBlock: () => PromiseLike<T>): PromiseLike<Try<T, E>>;
export declare function tc<T, E extends Error = Error>(block: () => T): Try<T, E>;
export declare function tc<T, E extends Error = Error>(promise: PromiseLike<T>): PromiseLike<Try<T, E>>;
export declare function isError(e: unknown): e is Error;