An integer that identifies the term in the ZIO sum type to which this instance belongs (e.g. IO.Tags.Succeed).

Returns the logical conjunction of the Boolean value returned by this effect and the Boolean value returned by the specified effect. This operator has "short circuiting" behavior so if the value returned by this effect is false the specified effect will not be evaluated.

Returns an effect that executes both this effect and the specified effect, in parallel, returning result of provided effect. If either side fails, then the other side will be interrupted.

Returns an effect that executes both this effect and the specified effect, in parallel, this effect result returned. If either side fails, then the other side will be interrupted.

Returns an effect that executes both this effect and the specified effect, in parallel, combining their results into a tuple. If either side fails, then the other side will be interrupted.

Alias for flatMap.

val parsed = readFile("foo.txt") >>= parseFile

Returns an effect that submerges the error case of an Either into the ZIO. The inverse operation of ZIO.either.

Uncurried version. Doesn't offer curried syntax and has worse type-inference characteristics, but it doesn't allocate intermediate zio.ZIO.BracketAcquire_ and zio.ZIO.BracketRelease_ objects.

Returns an effect that, if evaluated, will return the cached result of this effect. Cached results will expire after timeToLive duration.

Returns an effect that, if evaluated, will return the cached result of this effect. Cached results will expire after timeToLive duration. In addition, returns an effect that can be used to invalidate the current cached value before the timeToLive duration expires.

Recovers from all errors.

openFile("config.json").catchAll(_ => IO.succeed(defaultConfig))

Recovers from all errors with provided Cause.

openFile("config.json").catchAllCause(_ => IO.succeed(defaultConfig))

Recovers from all defects with provided function.

effect.catchSomeDefect(_ => backup())

WARNING: There is no sensible way to recover from defects. This method should be used only at the boundary between ZIO and an external system, to transmit information on a defect for diagnostic or explanatory purposes.

Recovers from all NonFatal Throwables.

openFile("data.json").catchNonFatalOrDie(_ => openFile("backup.json"))

Recovers from some or all of the error cases.

openFile("data.json").catchSome {
  case _: FileNotFoundException => openFile("backup.json")
}

Recovers from some or all of the error cases with provided cause.

openFile("data.json").catchSomeCause {
  case c if (c.interrupted) => openFile("backup.json")
}

Recovers from some or all of the defects with provided partial function.

effect.catchSomeDefect {
  case _: SecurityException => backup()
}

WARNING: There is no sensible way to recover from defects. This method should be used only at the boundary between ZIO and an external system, to transmit information on a defect for diagnostic or explanatory purposes.

Taps the effect, printing the result of calling .toString on the value. Prefixes the output with the given message.

Returns an effect whose interruption will be disconnected from the fiber's own interruption, being performed in the background without slowing down the fiber's interruption.

This method is useful to create "fast interrupting" effects. For example, if you call this on a bracketed effect, then even if the effect is "stuck" in acquire or release, its interruption will return immediately, while the acquire / release are performed in the background.

See timeout and race for other applications.

Returns an effect whose failure and success have been lifted into an Either.The resulting effect cannot fail, because the failure case has been exposed as part of the Either success case.

This method is useful for recovering from ZIO effects that may fail.

The error parameter of the returned ZIO is Nothing, since it is guaranteed the ZIO effect does not model failure.

Returns an effect that, if this effect _starts_ execution, then the specified finalizer is guaranteed to begin execution, whether this effect succeeds, fails, or is interrupted.

For use cases that need access to the effect's result, see ZIO#onExit.

Finalizers offer very powerful guarantees, but they are low-level, and should generally not be used for releasing resources. For higher-level logic built on ensuring, see ZIO#bracket.

Returns an effect that models the execution of this effect, followed by the passing of its value to the specified continuation function k, followed by the effect that it returns.

val parsed = readFile("foo.txt").flatMap(file => parseFile(file))

Creates a composite effect that represents this effect followed by another one that may depend on the error produced by this one.

val parsed = readFile("foo.txt").flatMapError(error => logErrorToFile(error))

Returns an effect that performs the outer effect first, followed by the inner effect, yielding the value of the inner effect.

This method can be used to "flatten" nested effects.

Returns an effect that swaps the error/success cases. This allows you to use all methods on the error channel, possibly before flipping back.

Recovers from errors by accepting one effect to execute for the case of an error, and one effect to execute for the case of success.

This method has better performance than either since no intermediate value is allocated and does not require subsequent calls to flatMap to define the next effect.

The error parameter of the returned IO may be chosen arbitrarily, since it will depend on the IOs returned by the given continuations.

Repeats this effect forever (until the first error). For more sophisticated schedules, see the repeat method.

Returns an effect that forks this effect into its own separate fiber, returning the fiber immediately, without waiting for it to begin executing the effect.

You can use the fork method whenever you want to execute an effect in a new fiber, concurrently and without "blocking" the fiber executing other effects. Using fibers can be tricky, so instead of using this method directly, consider other higher-level methods, such as raceWith, zipPar, and so forth.

The fiber returned by this method has methods to interrupt the fiber and to wait for it to finish executing the effect. See zio.Fiber for more information.

Whenever you use this method to launch a new fiber, the new fiber is attached to the parent fiber's scope. This means when the parent fiber terminates, the child fiber will be terminated as well, ensuring that no fibers leak. This behavior is called "auto supervision", and if this behavior is not desired, you may use the forkDaemon or forkIn methods.

for {
  fiber <- subtask.fork
  // Do stuff...
  a <- fiber.join
} yield a

Forks the effect into a new fiber attached to the global scope. Because the new fiber is attached to the global scope, when the fiber executing the returned effect terminates, the forked fiber will continue running.

Forks an effect that will be executed without unhandled failures being reported. This is useful for implementing combinators that handle failures themselves.

Forks the fiber in a ZManaged. Using the ZManaged value will execute the effect in the fiber, while ensuring its interruption when the effect supplied to ZManaged#use completes.

Returns a new effect whose scope will be extended by the specified scope. This means any finalizers associated with the effect will not be executed until the specified scope is closed.

Switches the interrupt status for this effect. If true is used, then the effect becomes interruptible (the default), while if false is used, then the effect becomes uninterruptible. These changes are compositional, so they only affect regions of the effect.

Returns a new effect that performs the same operations as this effect, but interruptibly, even if composed inside of an uninterruptible region.

Note that effects are interruptible by default, so this function only has meaning if used within an uninterruptible region.

WARNING: This operator "punches holes" into effects, allowing them to be interrupted in unexpected places. Do not use this operator unless you know exactly what you are doing. Instead, you should use ZIO.uninterruptibleMask.

Returns an effect which is guaranteed to be executed on the specified executor. The specified effect will always run on the specified executor, even in the presence of asynchronous boundaries.

This is useful when an effect must be executed somewhere, for example: on a UI thread, inside a client library's thread pool, inside a blocking thread pool, inside a low-latency thread pool, or elsewhere.

The lock function composes with the innermost lock taking priority. Use of this method does not alter the execution semantics of other effects composed with this one, making it easy to compositionally reason about where effects are running.

Returns an effect with its error channel mapped using the specified function. This can be used to lift a "smaller" error into a "larger" error.

Returns an effect with its full cause of failure mapped using the specified function. This can be used to transform errors while preserving the original structure of Cause.

Runs the specified effect if this effect fails, providing the error to the effect if it exists. The provided effect will not be interrupted.

Returns this effect if environment is on the left, otherwise returns whatever is on the right unmodified. Note that the result is lifted in either.

Returns this effect if environment is on the right, otherwise returns whatever is on the left unmodified. Note that the result is lifted in either.

Provides the part of the environment that is not part of the ZEnv, leaving an effect that only depends on the ZEnv.

val loggingLayer: ZLayer[Any, Nothing, Logging] = ???

val zio: ZIO[ZEnv with Logging, Nothing, Unit] = ???

val zio2 = zio.provideCustomLayer(loggingLayer)

Provides some of the environment required to run this effect, leaving the remainder R0.

If your environment has the type Has[_], please see zio.ZIO.provideSomeLayer

val effect: ZIO[Console with Logging, Nothing, Unit] = ???

effect.provideSome[Console](env =>
  new Console with Logging {
    val console = env.console
    val logging = new Logging.Service[Any] {
      def log(line: String) = console.putStrLn(line)
    }
  }
)

Splits the environment into two parts, providing one part using the specified layer and leaving the remainder R0.

val clockLayer: ZLayer[Any, Nothing, Clock] = ???

val zio: ZIO[Clock with Random, Nothing, Unit] = ???

val zio2 = zio.provideSomeLayer[Random](clockLayer)

Returns an effect that races this effect with the specified effect, returning the first successful A from the faster side. If one effect succeeds, the other will be interrupted. If neither succeeds, then the effect will fail with some error.

WARNING: The raced effect will safely interrupt the "loser", but will not resume until the loser has been cleanly terminated. If early return is desired, then instead of performing l race r, perform l.disconnect race r.disconnect, which disconnects left and right interruption signals, allowing a fast return, with interruption performed in the background.

Note that if the race is embedded into an uninterruptible region, then because the loser cannot be interrupted, it will be allowed to continue executing in the background, without delaying the return of the race.

Returns an effect that races this effect with all the specified effects, yielding the value of the first effect to succeed with a value. Losers of the race will be interrupted immediately

Returns an effect that races this effect with the specified effect, yielding the first result to succeed. If neither effect succeeds, then the composed effect will fail with some error.

WARNING: The raced effect will safely interrupt the "loser", but will not resume until the loser has been cleanly terminated. If early return is desired, then instead of performing l raceEither r, perform l.disconnect raceEither r.disconnect, which disconnects left and right interrupt signal, allowing the earliest possible return.

Returns an effect that races this effect with the specified effect, yielding the first result to complete, whether by success or failure. If neither effect completes, then the composed effect will not complete.

WARNING: The raced effect will safely interrupt the "loser", but will not resume until the loser has been cleanly terminated. If early return is desired, then instead of performing l raceFirst r, perform l.disconnect raceFirst r.disconnect, which disconnects left and right interrupt signal, allowing a fast return, with interruption performed in the background.

Attach a wrapping trace pointing to this location in case of error.

Useful when joining fibers to make the resulting trace mention the join point, otherwise only the traces of joined fibers are included.

for {
  badFiber <- UIO(1 / 0).fork
  _ <- badFiber.join.refailWithTrace
} yield ()

Returns a new effect that repeats this effect according to the specified schedule or until the first failure. Scheduled recurrences are in addition to the first execution, so that io.repeat(Schedule.once) yields an effect that executes io, and then if that succeeds, executes io an additional time.

Returns a new effect that repeats this effect according to the specified schedule or until the first failure, at which point, the failure value and schedule output are passed to the specified handler.

Scheduled recurrences are in addition to the first execution, so that io.repeat(Schedule.once) yields an effect that executes io, and then if that succeeds, executes io an additional time.

Returns a new effect that repeats this effect according to the specified schedule or until the first failure, at which point, the failure value and schedule output are passed to the specified handler.

Scheduled recurrences are in addition to the first execution, so that io.repeat(Schedule.once) yields an effect that executes io, and then if that succeeds, executes io an additional time.

Unearth the unchecked failure of the effect. (opposite of orDie)

val f0: Task[Unit] = ZIO.fail(new Exception("failing")).unit
val f1: UIO[Unit]  = f0.orDie
val f2: Task[Unit] = f1.resurrect

Retries with the specified retry policy. Retries are done following the failure of the original io (up to a fixed maximum with once or recurs for example), so that that io.retry(Schedule.once) means "execute io and in case of failure, try again once".

Exposes the full cause of failure of this effect.

final case class DomainError()

val veryBadIO: IO[DomainError, Unit] =
  IO.effectTotal(5 / 0) *> IO.fail(DomainError())

val caught: IO[DomainError, Unit] =
  veryBadIO.sandbox.mapError(_.untraced).catchAll {
    case Cause.Die(_: ArithmeticException) =>
      // Caught defect: divided by zero!
      IO.unit
    case Cause.Fail(_) =>
      // Caught error: DomainError!
      IO.unit
    case cause =>
      // Caught unknown defects, shouldn't recover!
      IO.halt(cause)
  }

Companion helper to sandbox. Allows recovery, and partial recovery, from errors and defects alike, as in:

case class DomainError()

val veryBadIO: IO[DomainError, Unit] =
  IO.effectTotal(5 / 0) *> IO.fail(DomainError())

val caught: IO[DomainError, Unit] =
  veryBadIO.sandboxWith(_.catchSome {
    case Cause.Die(_: ArithmeticException)=>
      // Caught defect: divided by zero!
      IO.succeed(0)
  })

Using sandboxWith with catchSome is better than using io.sandbox.catchAll with a partial match, because in the latter, if the match fails, the original defects will be lost and replaced by a MatchError

Runs this effect according to the specified schedule.

See scheduleFrom for a variant that allows the schedule's decision to depend on the result of this effect.

Returns an effect that effectfully "peeks" at the success of this effect.

readFile("data.json").tap(putStrLn)

Returns an effect that effectfully "peeks" at the failure or success of this effect.

readFile("data.json").tapBoth(logError(_), logData(_))

Returns an effect that effectually "peeks" at the cause of the failure of this effect.

readFile("data.json").tapCause(logCause(_))

Returns an effect that effectfully "peeks" at the result of this effect.

readFile("data.json").tapEither(result => log(result.fold("Error: " + _, "Success: " + _)))

Returns an effect that effectfully "peeks" at the failure of this effect.

readFile("data.json").tapError(logError(_))

Returns an effect that effectfully "peeks" at the success of this effect. If the partial function isn't defined at the input, the result is equivalent to the original effect.

readFile("data.json").tapSome {
  case content if content.nonEmpty => putStrLn(content)
}

Returns an effect that will timeout this effect, returning None if the timeout elapses before the effect has produced a value; and returning Some of the produced value otherwise.

If the timeout elapses without producing a value, the running effect will be safely interrupted.

WARNING: The effect returned by this method will not itself return until the underlying effect is actually interrupted. This leads to more predictable resource utilization. If early return is desired, then instead of using effect.timeout(d), use effect.disconnect.timeout(d), which first disconnects the effect's interruption signal before performing the timeout, resulting in earliest possible return, before an underlying effect has been successfully interrupted.

Returns an effect that will timeout this effect, returning either the default value if the timeout elapses before the effect has produced a value; and or returning the result of applying the function f to the success value of the effect.

If the timeout elapses without producing a value, the running effect will be safely interrupted

IO.succeed(1).timeoutTo(None)(Some(_))(1.second)

Returns an effect that keeps or breaks a promise based on the result of this effect. Synchronizes interruption, so if this effect is interrupted, the specified promise will be interrupted, too.

Converts this ZIO to zio.Managed. This ZIO and the provided release action will be performed uninterruptibly.

Converts this ZIO to zio.ZManaged with no release action. It will be performed interruptibly.

Enables ZIO tracing for this effect. Because this is the default, this operation only has an additional meaning if the effect is located within an untraced section, or the current fiber has been spawned by a parent inside an untraced section.

Toggles ZIO tracing support for this effect. If true is used, then the effect will accumulate traces, while if false is used, then tracing is disabled. These changes are compositional, so they only affect regions of the effect.

When this effect succeeds with a cause, then this method returns a new effect that either fails with the cause that this effect succeeded with, or succeeds with unit, depending on whether the cause is empty.

This operation is the opposite of cause.

Performs this effect uninterruptibly. This will prevent the effect from being terminated externally, but the effect may fail for internal reasons (e.g. an uncaught error) or terminate due to defect.

Uninterruptible effects may recover from all failure causes (including interruption of an inner effect that has been made interruptible).

The inverse operation to sandbox. Submerges the full cause of failure.

Disables ZIO tracing facilities for the duration of the effect.

Note: ZIO tracing is cached, as such after the first iteration it has a negligible effect on performance of hot-spots (Additional hash map lookup per flatMap). As such, using untraced sections is not guaranteed to result in a noticeable performance increase.

Sequentially zips the this result with the specified result. Combines both Cause[E1] when both effects fail.

Returns an effect that executes both this effect and the specified effect, in parallel. Combines both Cause[E1] when both effects fail.

Sequentially zips this effect with the specified effect using the specified combiner function. Combines the causes in case both effect fail.

Returns an effect that executes both this effect and the specified effect, in parallel, combining their results with the specified f function. If both sides fail, then the cause will be combined.