@onrails/result

import { R as Result, U as UnexpectedError } from './types-BQ9vv0nD.js'; /** * @onrails/result internal — the single payload-extraction pair. * * `InferOk` / `InferErr` pull the success/error type out of a {@link Result} * (tagged union) or a {@link ResultAsync} (class carrier), resolving to * `never` for anything else. Every module that needs to extract a payload * type imports from here; do not redeclare local copies. * * Internal only: not listed in package.json `exports` or tsup entries. * The package index re-exports the pair under the same names. */ /** * Extracts the `Ok` value type from a {@link Result} or {@link ResultAsync}, * resolving to `never` for any other type. * * @example * ```ts * type T = InferOk<Result<number, string>>; // number * type U = InferOk<ResultAsync<User, AppError>>; // User * ``` */ type InferOk<R> = R extends { _tag: "Ok"; readonly value: infer T; } ? T : R extends ResultAsync<infer T, unknown> ? T : never; /** * Extracts the `Err` error type from a {@link Result} or {@link ResultAsync}, * resolving to `never` for any other type. Mirror of {@link InferOk}. * * @example * ```ts * type E = InferErr<Result<number, string>>; // string * type F = InferErr<ResultAsync<User, AppError>>; // AppError * ``` */ type InferErr<R> = R extends { _tag: "Err"; readonly error: infer E; } ? E : R extends ResultAsync<unknown, infer E> ? E : never; type PromiseFactory<T, E> = () => Promise<Result<T, E>>; type CombineTupleAsync<R extends readonly ResultAsync<unknown, unknown>[]> = ResultAsync<{ [K in keyof R]: InferOk<R[K]>; }, { [K in keyof R]: InferErr<R[K]>; }[number]>; /** * Async railway carrier. Wraps a deferred `Promise<Result<T, E>>` and exposes * the same dual-track transforms as the sync {@link Result} — `map`, `flatMap`, * `recover`, `tap`, `match`. The public API never surfaces `Promise<Result<…>>` * directly: `await` the instance (it is thenable) or call {@link resolve} / * {@link match} to settle it. * * Construct via the static factories ({@link ok}, {@link err}, {@link fromPromise}, * {@link defer}, …) rather than `new` — the constructor is `protected`. * * @typeParam T - the `Ok` value type * @typeParam E - the `Err` error type * * @example * ```ts * const user = ResultAsync.fromPromise(api.getUser(id), toAppError) * .map((u) => u.profile) * .recover(() => ResultAsync.ok(guestProfile)); * * const r = await user; // Result<Profile, AppError> * ``` */ declare class ResultAsync<T, E> { protected readonly run: PromiseFactory<T, E>; private promise; protected constructor(run: PromiseFactory<T, E>); /** * Lifts an already-settled sync {@link Result} into a {@link ResultAsync}. * * @example * ```ts * const ra = ResultAsync.fromResult(ok(42)); // ResultAsync<number, never> * ``` */ static fromResult<T, E>(result: Result<T, E>): ResultAsync<T, E>; /** * Wraps a `PromiseLike<T>` that may reject. Rejections pass through `onReject` * to become a typed `Err`; resolution becomes `Ok<T>`. * * @param promise - the promise to wrap * @param onReject - maps a rejection reason to the `Err` channel * * @example * ```ts * const body = ResultAsync.fromPromise( * fetch(url).then((r) => r.text()), * (e): NetError => ({ kind: "net", cause: String(e) }), * ); * ``` */ static fromPromise<T, E>(promise: PromiseLike<T>, onReject: (error: unknown) => E): ResultAsync<T, E>; /** * Wraps a `PromiseLike<T>` that is **guaranteed not to reject**, skipping the * `onReject` mapper. Use only when rejection is provably impossible. * * @example * ```ts * const now = ResultAsync.fromSafePromise(Promise.resolve(Date.now())); * ``` */ static fromSafePromise<T, E = never>(promise: PromiseLike<T>): ResultAsync<T, E>; /** * Defers work until {@link resolve}. Unlike {@link fromPromise}, the factory * does not run until the `ResultAsync` is resolved (e.g. by `combineTuple` / * `combineTupleParallel`). The factory runs at most once — `resolve` memoizes. * * @example * ```ts * const insert = ResultAsync.defer(() => db.orders.insert(row)); * // nothing has run yet * const r = await insert; // factory runs exactly once here * ``` */ static defer<T, E>(fn: () => Promise<Result<T, E>>): ResultAsync<T, E>; /** * Lifts a value into an `Ok` async result. * * @example * ```ts * const r = ResultAsync.ok(42); // ResultAsync<number, never> * ``` */ static ok<T>(value: T): ResultAsync<T, never>; static ok<T, E>(value: T): ResultAsync<T, E>; /** * Fantasy Land `pure` — alias of {@link ResultAsync.ok}. One lift name * shared across the trio (`of` / `Maybe.of` / `ResultAsync.of`). */ static of<T>(value: T): ResultAsync<T, never>; static of<T, E>(value: T): ResultAsync<T, E>; /** * Lifts an error into an `Err` async result. * * @example * ```ts * const r = ResultAsync.err({ kind: "not_found" as const }); * ``` */ static err<T = never, E = unknown>(error: E): ResultAsync<T, E>; /** * Lifts an existing `Promise<Result<T, E>>` (e.g. from interop code) into a * {@link ResultAsync}. A thrown defect is routed through `onDefect`, * defaulting to {@link UnexpectedError}. The `Ok` value passes through * verbatim — even when it happens to be Result-shaped. * * @param promise - a promise that already yields a `Result` * @param onDefect - maps an unexpected throw to the `Err` channel * @see {@link fromAsync} from `@onrails/result` */ static fromResultPromise<T, E>(promise: Promise<Result<T, E>>, onDefect?: (error: unknown) => E | UnexpectedError): ResultAsync<T, E | UnexpectedError>; /** * Combines a homogeneous array of async results into one. Resolves * **sequentially** in input order, short-circuiting on the first `Err`. * For heterogeneous tuples that preserve per-index types, use * {@link combineTuple}; for wall-clock overlap, {@link combineTupleParallel}. * * @example * ```ts * const all = ResultAsync.combine([loadA(), loadB(), loadC()]); * // ResultAsync<Item[], LoadError> * ``` */ static combine<T, E>(results: readonly ResultAsync<T, E>[]): ResultAsync<T[], E>; /** * Heterogeneous async tuple combine — resolves branches **sequentially** * (left-to-right), returning the first `Err` in input order. Preserves each * branch's `Ok` type by position, so the result destructures type-safely. * This is the canonical sequential async combine (replaces the former * `sequenceTupleAsync`). * * @example * ```ts * const combined = ResultAsync.combineTuple([loadCfg(), loadCatalog()] as const); * // ResultAsync<readonly [Cfg, Catalog], CfgError | CatalogError> * const r = await combined; * if (isOk(r)) { * const [cfg, catalog] = r.value; // typed per position * } * ``` */ static combineTuple<const R extends readonly ResultAsync<unknown, unknown>[]>(results: R): CombineTupleAsync<R>; /** * Like {@link combineTuple}, but starts every branch before awaiting (wall-clock * parallel for independent IO). On failure, returns the first `Err` in input order. * * @example * ```ts * // independent IO — overlap them * const combined = ResultAsync.combineTupleParallel([ * loadProfile(id), * loadMetrics(id), * ] as const); * ``` */ static combineTupleParallel<const R extends readonly ResultAsync<unknown, unknown>[]>(results: R): CombineTupleAsync<R>; /** * Transforms the `Ok` value, passing `Err` through unchanged. * * @example * ```ts * ResultAsync.ok(2).map((n) => n * 3); // ResultAsync<number> → Ok 6 * ``` */ map<U>(fn: (value: T) => U): ResultAsync<U, E>; /** * Transforms the `Err` value, passing `Ok` through unchanged — useful for * unifying heterogeneous failures into one app-level union. * * @example * ```ts * load(id).mapErr((e): AppError => ({ kind: "load", cause: e })); // ResultAsync<T, AppError> * ``` */ mapErr<F>(fn: (error: E) => F): ResultAsync<T, F>; /** * Canonical bind — chains a step that itself returns a `ResultAsync` or sync * `Result`, short-circuiting on `Err`. Error types accumulate (`E | F`). * * @example * ```ts * authenticate(req) * .flatMap((user) => loadProfile(user.id)) // ResultAsync * .flatMap((p) => validate(p)); // sync Result also accepted * ``` */ flatMap<U, F = E>(fn: (value: T) => ResultAsync<U, F> | Result<U, F>): ResultAsync<U, E | F>; /** * neverthrow-compat alias of {@link flatMap}. Kept as the documented compat * tier; prefer {@link flatMap} in new code. * * @example * ```ts * authenticate(req).andThen((user) => loadProfile(user.id)); * ``` */ andThen<U, F = E>(fn: (value: T) => ResultAsync<U, F> | Result<U, F>): ResultAsync<U, E | F>; /** * Error-channel bind — runs `fn` only on `Err`, swapping in a recovery * `ResultAsync` or sync `Result`. `Ok` passes through. The mirror of * {@link flatMap} on the error track. * * @example * ```ts * loadFromCache(id).recover(() => loadFromOrigin(id)); // ResultAsync<T, F> * ``` */ recover<F>(fn: (error: E) => ResultAsync<T, F> | Result<T, F>): ResultAsync<T, F>; /** * neverthrow-compat alias of {@link recover}. Kept as the documented compat * tier; prefer {@link recover} in new code. * * @example * ```ts * loadFromCache(id).orElse(() => loadFromOrigin(id)); * ``` */ orElse<F>(fn: (error: E) => ResultAsync<T, F> | Result<T, F>): ResultAsync<T, F>; /** * Runs a side effect on the `Ok` value and passes the result through * unchanged; a no-op on `Err`. Mirrors {@link tapErr}. * * @example * ```ts * saveUser(u).tap((saved) => analytics.track("user_saved", saved.id)); * ``` */ tap(fn: (value: T) => void): ResultAsync<T, E>; /** * Runs a side effect on the `Err` value and passes the result through * unchanged; a no-op on `Ok`. The error-track mirror of {@link tap}. * * @example * ```ts * saveUser(u).tapErr((e) => logger.warn("save failed", e)); * ``` */ tapErr(fn: (error: E) => void): ResultAsync<T, E>; /** * Settles to the `Ok` value, or `defaultValue` if `Err`. Terminal — returns a * plain `Promise`, not a `ResultAsync`. * * @example * ```ts * const profile = await loadProfile(id).unwrapOr(guestProfile); * ``` */ unwrapOr<U>(defaultValue: U): Promise<T | U>; /** * Terminal collapse — folds both tracks into a single awaited value. Returns * a plain `Promise`, settling the carrier exactly once. * * @param onOk - handles the `Ok` value * @param onErr - handles the `Err` value * * @example * ```ts * const status = await save(row).match( * () => 200, * (e) => (e.kind === "conflict" ? 409 : 500), * ); * ``` */ match<U1, U2 = U1>(onOk: (value: T) => U1, onErr: (error: E) => U2): Promise<U1 | U2>; /** * Settles the carrier to a bare sync {@link Result}, memoizing so the * underlying factory runs at most once. Prefer `await ra` (the thenable) or * {@link match} in app code; use `resolve` when you need the tagged union back. * * @example * ```ts * const r = await load(id).resolve(); // Result<Data, LoadError> * if (isOk(r)) use(r.value); * ``` */ resolve(): Promise<Result<T, E>>; /** * Thenable shim — `await ra` resolves to a bare tagged-union `Result<T, E>`. * Narrow with `isOk(r)` / `isErr(r)` to read `.value` / `.error`. */ then<R1 = Result<T, E>, R2 = never>(onfulfilled?: ((value: Result<T, E>) => R1 | PromiseLike<R1>) | undefined | null, onrejected?: ((reason: unknown) => R2 | PromiseLike<R2>) | undefined | null): Promise<R1 | R2>; } export { type InferErr as I, ResultAsync as R, type InferOk as a };