Promise

A promise represents an asynchronous variable that can be set exactly once, with the ability for an arbitrary number of fibers to suspend (by calling get) and automatically resume when the variable is set.

Promises can be used for building primitive actions whose completions require the coordinated action of multiple fibers, and for building higher-level concurrent or asynchronous structures.

for {
  promise <- Promise.make[Nothing, Int]
  _       <- promise.complete(42).delay(1.second).fork
  value   <- promise.get // Resumes when forked fiber completes promise
} yield value

Linear Supertypes

AnyVal, Any

Value Members

final def !=(arg0: Any): Boolean

Definition Classes
Any
final def ##(): Int

Definition Classes
Any
final def ==(arg0: Any): Boolean

Definition Classes
Any
final def asInstanceOf[T0]: T0

Definition Classes
Any
final def await: IO[E, A]

Retrieves the value of the promise, suspending the fiber running the action until the result is available.
final def done(io: IO[E, A]): IO[Nothing, Boolean]

Completes the promise with the specified result.
Completes the promise with the specified result. If the specified promise has already been completed, the method will produce false.
final def fail(e: E): IO[Nothing, Boolean]

Fails the promise with the specified error, which will be propagated to all fibers waiting on the value of the promise.
def getClass(): Class[_ <: AnyVal]

Definition Classes
AnyVal → Any
final def interrupt: IO[Nothing, Boolean]

Completes the promise with interruption.
Completes the promise with interruption. This will interrupt all fibers waiting on the value of the promise.
final def isInstanceOf[T0]: Boolean

Definition Classes
Any
final def poll: IO[Nothing, Option[IO[E, A]]]

Completes immediately this promise and returns optionally it's result.
final def succeed(a: A): IO[Nothing, Boolean]

Completes the promise with the specified value.
def toString(): String

Definition Classes
Any

Related Docs: object Promise | package zio

final class Promise[E, A] extends AnyVal

Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: Any): Boolean

final def asInstanceOf[T0]: T0

final def await: IO[E, A]

final def done(io: IO[E, A]): IO[Nothing, Boolean]

final def fail(e: E): IO[Nothing, Boolean]

def getClass(): Class[_ <: AnyVal]

final def interrupt: IO[Nothing, Boolean]

final def isInstanceOf[T0]: Boolean

final def poll: IO[Nothing, Option[IO[E, A]]]

final def succeed(a: A): IO[Nothing, Boolean]

def toString(): String

Inherited from AnyVal

Inherited from Any

Ungrouped