ZManaged

A scope in which resources can be safely preallocated. Passing a ZManaged to the apply method will create (inside an effect) a managed resource which is already acquired and cannot fail.

A ReleaseMap represents the finalizers associated with a scope.

The design of ReleaseMap is inspired by ResourceT, written by Michael Snoyman @snoyberg. (https://github.com/snoyberg/conduit/blob/master/resourcet/Control/Monad/Trans/Resource/Internal.hs)

A scope in which ZManaged values can be safely allocated. Passing a managed resource to the apply method will return an effect that allocates the resource and returns it with an early-release handle.

A ZManagedConstructor[Input] knows how to construct a ZManaged value from an input of type Input. This allows the type of the ZManaged value constructed to depend on Input.

A finalizer used in a ReleaseMap. The Exit value passed to it is the result of executing ZManaged#use or an arbitrary value passed into ReleaseMap#release.

Submerges the error case of an Either into the ZManaged. The inverse operation of ZManaged.either.

Lifts a ZIO[R, E, A] into ZManaged[R, E, A] with a release action that does not need access to the resource. The acquire and release actions will be performed uninterruptibly.

Lifts a synchronous effect into ZManaged[R, Throwable, A] with a release action that does not need access to the resource. The acquire and release actions will be performed uninterruptibly.

Lifts a synchronous effect into ZManaged[R, Throwable, A] with a release action. The acquire and release actions will be performed uninterruptibly.

Lifts a ZIO[R, E, A] into ZManaged[R, E, A] with a release action that does not need access to the resource but handles Exit. The acquire and release actions will be performed uninterruptibly.

Lifts a ZIO[R, E, A] into ZManaged[R, E, A] with a release action that handles Exit. The acquire and release actions will be performed uninterruptibly.

Lifts a ZIO[R, E, A] into ZManaged[R, E, A] with a release action that does not require access to the resource. The acquire action will be performed interruptibly, while release will be performed uninterruptibly.

Lifts a ZIO[R, E, A] into ZManaged[R, E, A] with a release action. The acquire action will be performed interruptibly, while release will be performed uninterruptibly.

Lifts a synchronous effect that does not throw exceptions into a ZManaged[Any, Nothing, A] with a release action that does not need access to the resource. The acquire and release actions will be performed uninterruptibly.

Lifts a synchronous effect that does not throw exceptions into a ZManaged[Any, Nothing, A] with a release action. The acquire and release actions will be performed uninterruptibly.

Lifts a ZIO[R, E, A] into ZManaged[R, E, A] with a release action. The acquire and release actions will be performed uninterruptibly.

Creates new ZManaged from a ZIO value that uses a ReleaseMap and returns a resource and a finalizer.

The correct usage of this constructor consists of:

• Properly registering a finalizer in the ReleaseMap as part of the ZIO value;
• Managing interruption safety - take care to use ZIO.uninterruptible or ZIO.uninterruptibleMask to verify that the finalizer is registered in the ReleaseMap after acquiring the value;
• Returning the finalizer returned from ReleaseMap#add. This is important to prevent double-finalization.

Lifts a synchronous side-effect into a ZManaged[R, Throwable, A], translating any thrown exceptions into typed failed effects.

Evaluate each effect in the structure from left to right, collecting the the successful values and discarding the empty cases. For a parallel version, see collectPar.

Evaluate each effect in the structure from left to right, and collect the results. For a parallel version, see collectAllPar.

Evaluate each effect in the structure from left to right, and discard the results. For a parallel version, see collectAllParDiscard.

Evaluate each effect in the structure in parallel, and collect the results. For a sequential version, see collectAll.

Evaluate each effect in the structure in parallel, and discard the results. For a sequential version, see collectAllDiscard.

Collects the first element of the Iterable[A] for which the effectual function f returns Some.

Evaluate each effect in the structure in parallel, collecting the the successful values and discarding the empty cases.

Similar to Either.cond, evaluate the predicate, return the given A as success if predicate returns true, and the given E as error otherwise

Returns an effect that dies with the specified Throwable. This method can be used for terminating a fiber because a defect has been detected in the code.

Returns an effect that dies with a java.lang.RuntimeException having the specified text message. This method can be used for terminating a fiber because a defect has been detected in the code.

Returns an effect from a lazily evaluated zio.Exit value.

Accesses the whole environment of the effect.

Create a managed that accesses the environment.

Create a managed that accesses the environment.

Create a managed that accesses the environment.

Determines whether any element of the Iterable[A] satisfies the effectual predicate f.

Returns an effect that models failure with the specified error. The moral equivalent of throw for pure code.

Returns an effect that models failure with the specified Cause.

Returns an effect that succeeds with the FiberId of the caller.

Creates an effect that only executes the provided finalizer as its release action.

Creates an effect that only executes the provided function as its release action.

Creates an effect that executes a finalizer stored in a Ref. The Ref is yielded as the result of the effect, allowing for control flows that require mutating finalizers.

Returns a managed resource that attempts to acquire the first managed resource and in case of failure, attempts to acquire each of the specified managed resources in order until one of them is successfully acquired, ensuring that the acquired resource is properly released after being used.

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 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.

Folds an Iterable[A] using an effectual function f, working sequentially from left to right.

Determines whether all elements of the Iterable[A] satisfy the effectual predicate f.

Applies the function f to each element of the Collection[A] and returns the results in a new Collection[B].

For a parallel version of this method, see foreachPar. If you do not need the results, see foreachDiscard for a more efficient implementation.

Applies the function f if the argument is non-empty and returns the results in a new Option[A2].

Applies the function f to each element of the Iterable[A] and runs produced effects sequentially.

Equivalent to foreach(as)(f).unit, but without the cost of building the list of results.

Applies the function f to each element of the Collection[A] and returns the result in a new Collection[B] using the specified execution strategy.

Applies the function f to each element of the Collection[A] in parallel, and returns the results in a new Collection[B].

For a sequential version of this method, see foreach.

Applies the function f to each element of the Iterable[A] and runs produced effects in parallel, discarding the results.

For a sequential version of this method, see foreachDiscard.

Constructs a ZManaged value of the appropriate type for the specified input.

Creates a ZManaged from an AutoCloseable resource. The resource's close method will be used as the release action.

Lifts an Either into a ZManaged value.

Lifts an Option into a ZManaged but preserves the error as an option in the error channel, making it easier to compose in some scenarios.

Lifts a pure Reservation[R, E, A] into ZManaged[R, E, A]. The acquisition step is performed interruptibly.

Creates a ZManaged from a Reservation produced by an effect. Evaluating the effect that produces the reservation will be performed uninterruptibly, while the acquisition step of the reservation will be performed interruptibly. The release step will be performed uninterruptibly as usual.

This two-phase acquisition allows for resource acquisition flows that can be safely interrupted and released.

Lifts a Try into a ZManaged.

Lifts a ZIO[R, E, A] into ZManaged[R, E, A] with no release action. The effect will be performed interruptibly.

Lifts a ZIO[R, E, A] into ZManaged[R, E, A] with no release action. The effect will be performed uninterruptibly. You usually want the ZManaged.fromZIO variant.

Runs onTrue if the result of b is true and onFalse otherwise.

Returns an effect that is interrupted as if by the fiber calling this method.

Returns an effect that is interrupted as if by the specified fiber.

Iterates with the specified effectual function. The moral equivalent of:

var s = initial

while (cont(s)) {
 s = body(s)
}

s

Returns a managed effect that describes shifting to the specified executor as the acquire action and shifting back to the original executor as the release action.

Logs the specified message at the current log level.

Annotates each log in managed effects composed after this.

Retrieves current log annotations.

Logs the specified message at the debug log level.

Logs the specified message at the error log level.

Logs the specified cause as an error.

Logs the specified message at the fatal log level.

Logs the specified message at the informational log level.

Sets the log level for managed effects composed after this.

Adjusts the label for the logging span for managed effects composed after this.

Logs the specified message at the trace log level.

Logs the specified message at the warning log level.

Loops with the specified effectual function, collecting the results into a list. The moral equivalent of:

var s  = initial
var as = List.empty[A]

while (cont(s)) {
 as = body(s) :: as
 s  = inc(s)
}

as.reverse

Loops with the specified effectual function purely for its effects. The moral equivalent of:

var s = initial

while (cont(s)) {
 body(s)
 s = inc(s)
}

Returns a memoized version of the specified resourceful function in the context of a managed scope. Each time the memoized function is evaluated a new resource will be acquired, if the function has not already been evaluated with that input, or else the previously acquired resource will be returned. All resources acquired by evaluating the function will be released at the end of the scope.

Merges an Iterable[ZManaged] to a single ZManaged, working sequentially.

Merges an Iterable[ZManaged] to a single ZManaged, working in parallel.

Due to the parallel nature of this combinator, f must be both:

• commutative: f(a, b) == f(b, a)
• associative: f(a, f(b, c)) == f(f(a, b), c)

Returns a ZManaged that never acquires a resource.

Returns a managed effect that describes shifting to the specified executor as the acquire action and shifting back to the original executor as the release action.

Retrieves the maximum number of fibers for parallel operators or None if it is unbounded.

Creates a scope in which resources can be safely preallocated.

Reduces an Iterable[IO] to a single IO, working sequentially.

Reduces an Iterable[IO] to a single IO, working in parallel.

Provides access to the entire map of resources allocated by this ZManaged.

Returns an ZManaged that accesses the runtime, which can be used to (unsafely) execute tasks. This is useful for integration with legacy code that must call back into ZIO code.

Creates a scope in which resources can be safely allocated into together with a release action.

Accesses the specified service in the environment of the effect.

Accesses the service corresponding to the specified key in the environment.

Accesses the specified service in the environment of the effect.

def foo(int: Int) = ZManaged.serviceWith[Foo](_.foo(int))

Effectfully accesses the specified managed service in the environment of the effect .

Especially useful for creating "accessor" methods on Services' companion objects accessing managed resources.

trait Foo {
 def start(): ZManaged[Any, Nothing, Unit]
}

def start: ZManaged[Foo, Nothing, Unit] =
 ZManaged.serviceWithManaged[Foo](_.start())

Effectfully accesses the specified service in the environment of the effect.

def foo(int: Int) = ZManaged.serviceWith[Foo](_.foo(int))

Returns a managed effect that describes shifting to the specified executor as the acquire action with no release action.

Returns an effect with the optional value.

Lifts a lazy, pure value into a Managed.

Returns a lazily constructed Managed.

Returns a ZManaged value that represents a managed resource that can be safely swapped within the scope of the ZManaged. The function provided inside the ZManaged can be used to switch the resource currently in use.

When the resource is switched, the finalizer for the previous finalizer will be executed uninterruptibly. If the effect executing inside the ZManaged#use is interrupted, the finalizer for the resource currently in use is guaranteed to execute.

This constructor can be used to create an expressive control flow that uses several instances of a managed resource. For example:

def makeWriter: Task[FileWriter]
trait FileWriter {
 def write(data: Int): Task[Unit]
 def close: UIO[Unit]
}

val elements = List(1, 2, 3, 4)
val writingProgram =
 ZManaged.switchable[Any, Throwable, FileWriter].use { switchWriter =>
   ZIO.foreachDiscard(elements) { element =>
     for {
       writer <- switchWriter(makeWriter.toManaged(_.close))
       _      <- writer.write(element)
     } yield ()
   }
 }

The moral equivalent of if (!p) exp

The moral equivalent of if (!p) exp when p has side-effects

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

Unwraps a ZManaged that is inside a ZIO.

The moral equivalent of if (p) exp

Runs an effect when the supplied PartialFunction matches for the given value, otherwise does nothing.

Runs an effect when the supplied PartialFunction matches for the given effectful value, otherwise does nothing.

The moral equivalent of if (p) exp when p has side-effects

Locally installs a supervisor and an effect that succeeds with all the children that have been forked in the returned effect.

Returns a managed effect that describes setting the specified maximum number of fibers for parallel operators as the acquire action and setting it back to the original value as the release action.

Returns a managed effect that describes setting an unbounded maximum number of fibers for parallel operators as the acquire action and setting it back to the original value as the release action.

Returns a ZManaged with the empty value.

Returns the effect resulting from mapping the success of this effect to unit.