Class ResultAsync<T, E>

A PromiseLike<Result<T, E>> that is directly await-able and supports chainable map / mapErr / andThen operators.

Example

const result = await ResultAsync.fromPromise(fetch('/api'), networkError)
  .andThen((res) =>
    ResultAsync.fromPromise(res.json() as Promise<unknown>, networkError)
  )

Type Parameters

Hierarchy (View Summary)

ResultAsync
- PaginatedResultAsync

Implements

PromiseLike<Result<T, E>>

Index

Constructors

constructor

Methods

andThen map mapErr match then unwrapOr fromPromise fromResult

Constructors

constructor

new ResultAsync<T, E>(promise: Promise<Result<T, E>>): ResultAsync<T, E>
Type Parameters
- T
- E
Parameters
- promise: Promise<Result<T, E>>
Returns ResultAsync<T, E>
- Defined in packages/core/src/result.ts:165

Methods

andThen

andThen<U, F>(
fn: (value: T) => ResultAsync<U, F> | Result<U, F>,
): ResultAsync<U, E | F>
Chains another async operation that may fail.

If the inner result is Err, fn is not called.
Type Parameters
- U
- F
Parameters
- fn: (value: T) => ResultAsync<U, F> | Result<U, F>
 Async mapper that returns a ResultAsync<U, F>
Returns ResultAsync<U, E | F>
- Defined in packages/core/src/result.ts:244

map

map(fn: (value: T) => U): ResultAsync<U, E>
Transforms the success value.

If the inner result is Err, fn is not called.
Type Parameters
- U
Parameters
- fn: (value: T) => U
 Synchronous mapper
Returns ResultAsync<U, E>
- Defined in packages/core/src/result.ts:217

mapErr

mapErr<F>(fn: (error: E) => F): ResultAsync<T, F>
Transforms the error value.

If the inner result is Ok, fn is not called.
Type Parameters
- F
Parameters
- fn: (error: E) => F
 Synchronous error mapper
Returns ResultAsync<T, F>
- Defined in packages/core/src/result.ts:231

match

match(
onOk: (value: T) => U | Promise,
onErr: (error: E) => U | Promise,
): Promise
Pattern-matches on success / failure.
Type Parameters
- U
Parameters
- onOk: (value: T) => U | Promise
 Called with the success value
- onErr: (error: E) => U | Promise
 Called with the error value
Returns Promise
A Promise
- Defined in packages/core/src/result.ts:266

then

then<TResult1 = Result<T, E>, TResult2 = never>(
 onfulfilled?:
 | ((value: Result<T, E>) => TResult1 | PromiseLike<TResult1>)
 | null,
 onrejected?: ((reason: unknown) => TResult2 | PromiseLike<TResult2>) | null,
): PromiseLike<TResult1 | TResult2>
Attaches callbacks for the resolution and/or rejection of the Promise.
Type Parameters
- TResult1 = Result<T, E>
- TResult2 = never
Parameters
- Optionalonfulfilled: ((value: Result<T, E>) => TResult1 | PromiseLike<TResult1>) | null
 The callback to execute when the Promise is resolved.
- Optionalonrejected: ((reason: unknown) => TResult2 | PromiseLike<TResult2>) | null
 The callback to execute when the Promise is rejected.
Returns PromiseLike<TResult1 | TResult2>
A Promise for the completion of which ever callback is executed.
Implementation of PromiseLike.then
- Defined in packages/core/src/result.ts:171

unwrapOr

unwrapOr(fallback: T): Promise<T>
Returns the success value, or fallback if the result is Err.
Parameters
- fallback: T
 The fallback value
Returns Promise<T>
- Defined in packages/core/src/result.ts:280

`Static`fromPromise

fromPromise<T, E>(
promise: Promise<T>,
onError: (reason: unknown) => E,
): ResultAsync<T, E>
Wraps a Promise<T> into a ResultAsync<T, E>.

If the promise rejects, onError maps the rejection reason to E.
Type Parameters
- T
- E
Parameters
- promise: Promise<T>
 The promise to wrap
- onError: (reason: unknown) => E
 Error mapper
Returns ResultAsync<T, E>
- Defined in packages/core/src/result.ts:189

`Static`fromResult

fromResult<T, E>(result: Result<T, E>): ResultAsync<T, E>
Wraps an already-resolved Result<T, E> into a ResultAsync<T, E>.
Type Parameters
- T
- E
Parameters
- result: Result<T, E>
 The result to wrap
Returns ResultAsync<T, E>
- Defined in packages/core/src/result.ts:206

Class ResultAsync<T, E>

Example

Type Parameters

Hierarchy (View Summary)

Implements

Index

Constructors

Methods

Constructors

constructor

Type Parameters

Parameters

Returns ResultAsync<T, E>

Methods

andThen

Type Parameters

Parameters

Returns ResultAsync<U, E | F>

map

Type Parameters

Parameters

Returns ResultAsync<U, E>

mapErr

Type Parameters

Parameters

Returns ResultAsync<T, F>

match

Type Parameters

Parameters

Returns Promise<U>

then

Type Parameters

Parameters

Returns PromiseLike<TResult1 | TResult2>

unwrapOr

Parameters

Returns Promise<T>

StaticfromPromise

Type Parameters

Parameters

Returns ResultAsync<T, E>

StaticfromResult

Type Parameters

Parameters

Returns ResultAsync<T, E>

Settings

On This Page

`Static`fromPromise

`Static`fromResult