ZIO

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

A symbolic alias for orDie.

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.

Sequentially zips this effect with the specified effect, combining the results into a tuple.

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.

Splits the environment, providing the first part to this effect and the second part to that effect.

A variant of flatMap that ignores the value produced by this effect.

Depending on provided environment, returns either this one or the other effect lifted in Left or Right, respectively.

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.

Sequences the specified effect after this effect, but ignores the value produced by the effect.

Alias for &&&.

A symbolic alias for orElseEither.

Operator alias for compose.

Operator alias for orElse.

A symbolic alias for raceEither.

Alias for flatMap.

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

Operator alias for andThen.

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

Attempts to convert defects into a failure, throwing away all information about the cause of the failure.

Attempts to convert defects into a failure, throwing away all information about the cause of the failure.

Maps the success value of this effect to the specified constant value.

Maps the success value of this effect to a service.

Maps the success value of this effect to an optional value.

Maps the error value of this effect to an optional value.

Returns a new effect that will not succeed with its value before first waiting for the end of all child fibers forked by the effect.

Shorthand for the uncurried version of ZIO.bracket.

Shorthand for the curried version of ZIO.bracket.

Like bracket, safely wraps a use and release of a resource. This resource will get automatically closed, because it implements AutoCloseable.

Shorthand for the uncurried version of ZIO.bracketExit.

Shorthand for the curried version of ZIO.bracketExit.

Executes the release effect only if there was an error.

A less powerful variant of bracket where the resource acquired by this effect is not needed.

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.

A version of catchAll that gives you the (optional) trace of the error.

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.

A version of catchSome that gives you the (optional) trace of the error.

Returns an effect that succeeds with the cause of failure of this effect, or Cause.empty if the effect did succeed.

Fail with e if the supplied PartialFunction does not match, otherwise succeed with the returned value.

Fail with e if the supplied PartialFunction does not match, otherwise continue with the returned value.

Taps the effect, printing the result of calling .toString on the value

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

Returns an effect that is delayed from this effect by the specified zio.duration.Duration.

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.

Acts on the children of this fiber (collected into a single fiber), guaranteeing the specified callback will be invoked, whether or not this effect succeeds.

Acts on the children of this fiber, guaranteeing the specified callback will be invoked, whether or not this effect succeeds.

Returns an effect that ignores errors and runs repeatedly until it eventually succeeds.

Maps this effect to the default exit codes.

Dies with specified Throwable if the predicate fails.

Dies with a java.lang.RuntimeException having the specified text message if the predicate fails.

Applies f if the predicate fails.

Supplies zio if the predicate fails.

Fails with e if the predicate fails.

Returns an effect that runs this effect and in case of failure, runs each of the specified effects in order until one of them succeeds.

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.

Unwraps the optional error, defaulting to the provided value.

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

Swaps the error/value parameters, applies the function f and flips the parameters back

Folds over the failure value or the success value to yield an effect that does not fail, but succeeds with the value returned by the left or right function passed to fold.

A more powerful version of fold that allows recovering from any kind of failure except interruptions.

A more powerful version of foldM that allows recovering from any kind of failure except interruptions.

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.

A version of foldM that gives you the (optional) trace of the error.

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 independent fiber, with the specified name.

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.

Forks an effect that will be executed on the specified ExecutionContext.

Like fork but handles an error with the provided handler.

Unwraps the optional success of this effect, but can fail with an None value.

Returns a successful effect with the head of the list if the list is non-empty or fails with the error None if the list is empty.

Returns a new effect that ignores the success or failure of this effect.

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.

Returns a new effect that will not succeed with its value before first interrupting all child fibers forked by the effect.

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 whether this effect is a failure.

Returns whether this effect is a success.

Joins this effect with the specified effect.

Returns a successful effect if the value is Left, or fails with the error None.

Returns a successful effect if the value is Left, or fails with the error e.

Returns a successful effect if the value is Left, or fails with a java.util.NoSuchElementException.

Returns a successful effect if the value is Left, or fails with the given error function 'e'.

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 whose success is mapped by the specified f function.

Returns an effect whose failure and success channels have been mapped by the specified pair of functions, f and g.

Returns an effect whose success is mapped by the specified side effecting f function, translating any thrown exceptions into typed failed effects.

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.

Returns an effect that, if evaluated, will return the lazily computed result of this effect.

Returns a new effect where the error channel has been merged into the success channel to their common combined type.

Returns a new effect where boolean value of this effect is negated.

Requires the option produced by this value to be None.

Executes the effect on the specified ExecutionContext and then shifts back to the default one.

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

Ensures that a cleanup functions runs, whether this effect succeeds, fails, or is interrupted.

Propagates the success value to the first element of a tuple, but passes the effect input R along unmodified as the second element of the tuple.

Runs the specified effect if this effect is interrupted.

Calls the specified function, and runs the effect it returns, if this effect is 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.

Propagates the success value to the second element of a tuple, but passes the effect input R along unmodified as the first element of the tuple.

Runs the specified effect if this effect is terminated, either because of a defect or because of interruption.

Returns an effect that will be executed at most once, even if it is evaluated multiple times.

Executes this effect, skipping the error but returning optionally the success.

Converts an option on errors into an option on values.

Translates effect failure into death of the fiber, making all failures unchecked and not a part of the type of the effect.

Keeps none of the errors, and terminates the fiber with them, using the specified function to convert the E into a Throwable.

Executes this effect and returns its value, if it succeeds, but otherwise executes the specified effect.

Returns an effect that will produce the value of this effect, unless it fails, in which case, it will produce the value of the specified effect.

Executes this effect and returns its value, if it succeeds, but otherwise fails with the specified error.

Returns an effect that will produce the value of this effect, unless it fails with the None value, in which case it will produce the value of the specified effect.

Executes this effect and returns its value, if it succeeds, but otherwise succeeds with the specified value.

Returns a new effect that will utilize the specified scope to supervise any fibers forked within the original effect.

Exposes all parallel errors in a single call

Provides the ZIO effect with its required environment, which eliminates its dependency on R.

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 a layer to the ZIO effect, which translates it to another level.

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.

Returns an effect that races this effect with the specified effect, calling the specified finisher as soon as one result or the other has been computed.

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 ()

Keeps some of the errors, and terminates the fiber with the rest

Keeps some of the errors, and terminates the fiber with the rest, using the specified function to convert the E into a Throwable.

Keeps some of the errors, and terminates the fiber with the rest.

Fail with the returned value if the PartialFunction matches, otherwise continue with our held value.

Continue with the returned computation if the PartialFunction matches, translating the successful match into a failure, otherwise continue with our held value.

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.

Repeats this effect the specified number of times.

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.

Repeats this effect until its value satisfies the specified predicate or until the first failure.

Repeats this effect until its value is equal to the specified value or until the first failure.

Repeats this effect until its value satisfies the specified effectful predicate or until the first failure.

Repeats this effect while its value satisfies the specified predicate or until the first failure.

Repeats this effect for as long as its value is equal to the specified value or until the first failure.

Repeats this effect while its value satisfies the specified effectful predicate or until the first failure.

Performs this effect the specified number of times and collects the results.

Performs this effect the specified number of times, discarding the results.

Returns a new effect that will utilize the default scope (fiber scope) to supervise any fibers forked within the original effect.

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".

Retries this effect the specified number of times.

Retries with the specified schedule, until it fails, and then both the value produced by the schedule together with the last error are passed to the recovery function.

Returns an effect that retries this effect with the specified schedule when it fails, until the schedule is done, then both the value produced by the schedule together with the last error are passed to the specified recovery function.

Retries this effect until its error satisfies the specified predicate.

Retries this effect until its error is equal to the specified error.

Retries this effect until its error satisfies the specified effectful predicate.

Retries this effect while its error satisfies the specified predicate.

Retries this effect for as long as its error is equal to the specified error.

Retries this effect while its error satisfies the specified effectful predicate.

Returns a successful effect if the value is Right, or fails with the error None.

Returns a successful effect if the value is Right, or fails with the given error 'e'.

Returns a successful effect if the value is Right, or fails with a java.util.NoSuchElementException.

Returns a successful effect if the value is Right, or fails with the given error function 'e'.

Returns an effect that semantically runs the effect on a fiber, producing an zio.Exit for the completion value of the fiber.

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.

Runs this effect according to the specified schedule starting from the specified input value.

Converts an option on values into an option on errors.

Extracts the optional value, or returns the given 'default'.

Extracts the optional value, or executes the effect 'default'.

Extracts the optional value, or fails with the given error 'e'.

Extracts the optional value, or fails with a java.util.NoSuchElementException

Summarizes a effect by computing some value before and after execution, and then combining the values to produce a summary, together with the result of execution.

Returns an effect with the behavior of this one, but where all child fibers forked in the effect are reported to the specified supervisor.

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 effectually "peeks" at the defect of this effect.