promise

Documentation

Index

• func New[T any]() (Resolver[T], Promise[T])
• type Promise
  • func Map[A, B any](p Promise[A], transform func(A) B) Promise[B]
  • func MapError[A any](p Promise[A], transform func(error) error) Promise[A]
• type Resolver

Functions

func New

func New[T any]() (Resolver[T], Promise[T])

New creates a new promise for value T. Returns a resolver and the promise.

Types

type Promise

type Promise[T any] interface {
	// Await blocks until the value is resolved or rejected.
	Await(context.Context) (T, error)
}

A promise for a future value.

func Map

func Map[A, B any](p Promise[A], transform func(A) B) Promise[B]

Map transforms the value of a promise with the provided function.

func MapError

func MapError[A any](p Promise[A], transform func(error) error) Promise[A]

MapError transforms the error of a rejected promise with the provided function.

type Resolver

type Resolver[T any] interface {
	// Resolve a promise. Unblocks all Await()s. Future calls of Await()
	// return the resolved value immediately.
	//
	// Only the first call to resolve (or reject) has an effect and
	// further calls are ignored.
	Resolve(T)

	// Reject a promise with an error.
	Reject(error)
}

Resolver can resolve or reject a promise. These methods are separate from 'Promise' to make it clear where the promise is resolved from.