Stream

Companion class Stream

object Stream extends StreamLowPriority

Source: Stream.scala

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StreamLowPriority, AnyRef, Any

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final class CompileOps[F[_], G[_], O] extends AnyRef
Projection of a Stream providing various ways to compile a Stream[F,O] to a G[...].
implicit final class FallibleOps[O] extends AnyVal
Provides syntax for fallible streams.
implicit final class IdOps[O] extends AnyVal
Provides syntax for pure pipes based on cats.Id.
implicit final class InvariantOps[F[_], O] extends AnyVal
A view of Stream that removes the variance from the type parameters.
A view of Stream that removes the variance from the type parameters. This allows defining syntax in which the type parameters appear in contravariant (i.e. input) position, which would fail to compile if defined as instance methods.
implicit final class NestedStreamOps[F[_], O] extends AnyVal
Provides syntax for streams of streams.
implicit final class NothingStreamOps[F[_]] extends AnyVal
implicit final class OptionStreamOps[F[_], O] extends AnyVal
final class PartiallyAppliedFromBlockingIterator[F[_]] extends AnyVal
final class PartiallyAppliedFromIterator[F[_]] extends AnyVal
implicit final class PipeOps[F[_], I, O] extends AnyVal
Provides operations on effectful pipes for syntactic convenience.
implicit final class PureOps[O] extends AnyVal
Provides syntax for pure streams.
implicit final class PurePipe2Ops[I, I2, O] extends AnyVal
Provides operations on pure pipes for syntactic convenience.
implicit final class PurePipeOps[I, O] extends AnyVal
Provides operations on pure pipes for syntactic convenience.
final class StepLeg[+F[_], +O] extends AnyRef
When merging multiple streams, this represents step of one leg.
When merging multiple streams, this represents step of one leg.
It is common to uncons, however unlike uncons, it keeps track of stream scope independently of the main scope of the stream.
This assures, that after each next stepLeg each Stream leg keeps its scope when interpreting.
Usual scenarios is to first invoke stream.pull.stepLeg and then consume whatever is available in leg.head. If the next step is required leg.stepLeg will yield next Leg.
Once the stream will stop to be interleaved (merged), then stream allows to return to normal stream invocation.
final class ToPull[F[_], O] extends AnyVal
Projection of a Stream providing various ways to get a Pull from the Stream.

Value Members

final def !=(arg0: Any): Boolean
Definition Classes
AnyRef → Any
final def ##: Int
Definition Classes
AnyRef → Any
final def ==(arg0: Any): Boolean
Definition Classes
AnyRef → Any

implicit def alignInstance[F[_]]: Align[[β$14$]Stream[F, β$14$]]

Align instance for Stream.

Align instance for Stream. * @example

scala> import cats.syntax.all._
scala> Stream(1,2,3).align(Stream("A","B","C","D","E")).toList
res0: List[cats.data.Ior[Int,String]] = List(Both(1,A), Both(2,B), Both(3,C), Right(D), Right(E))

def apply[F[x] >: Pure[x], O](os: O*): Stream[F, O]
Creates a pure stream that emits the supplied values.
Creates a pure stream that emits the supplied values. To convert to an effectful stream, use covary.
final def asInstanceOf[T0]: T0
Definition Classes
Any
def attemptEval[F[_], O](fo: F[O]): Stream[F, Either[Throwable, O]]
Creates a single element stream that gets its value by evaluating the supplied effect.
Creates a single element stream that gets its value by evaluating the supplied effect. If the effect fails, a Left is emitted. Otherwise, a Right is emitted.
Use eval instead if a failure while evaluating the effect should fail the stream.
Example:
1. scala> import cats.effect.SyncIO scala> Stream.attemptEval(SyncIO(10)).compile.toVector.unsafeRunSync() res0: Vector[Either[Throwable,Int]] = Vector(Right(10)) scala> Stream.attemptEval(SyncIO(throw new RuntimeException)).compile.toVector.unsafeRunSync() res1: Vector[Either[Throwable,Nothing]] = Vector(Left(java.lang.RuntimeException))
def awakeDelay[F[_]](period: FiniteDuration)(implicit t: Temporal[F]): Stream[F, FiniteDuration]
Light weight alternative to awakeEvery that sleeps for duration d before each pulled element.
def awakeEvery[F[_]](period: FiniteDuration, dampen: Boolean)(implicit t: Temporal[F]): Stream[F, FiniteDuration]
Discrete stream that every d emits elapsed duration since the start time of stream consumption.
Discrete stream that every d emits elapsed duration since the start time of stream consumption.
For example: awakeEvery[IO](5 seconds) will return (approximately) 5s, 10s, 15s, and will lie dormant between emitted values.
period
duration between emits of the resulting stream
dampen
whether missed periods result in 1 emitted tick or 1 per missed period, see fixedRate for more info
def awakeEvery[F[_]](period: FiniteDuration)(implicit arg0: Temporal[F]): Stream[F, FiniteDuration]
Discrete stream that every d emits elapsed duration since the start time of stream consumption.
Discrete stream that every d emits elapsed duration since the start time of stream consumption.
Missed periods are dampened to a single tick.
For example: awakeEvery[IO](5 seconds) will return (approximately) 5s, 10s, 15s, and will lie dormant between emitted values.
period
duration between emits of the resulting stream
def bracket[F[_], R](acquire: F[R])(release: (R) => F[Unit]): Stream[F, R]
Creates a stream that emits a resource allocated by an effect, ensuring the resource is eventually released regardless of how the stream is used.
Creates a stream that emits a resource allocated by an effect, ensuring the resource is eventually released regardless of how the stream is used.
A typical use case for bracket is working with files or network sockets. The resource effect opens a file and returns a reference to it. One can then flatMap on the returned Stream to access the file, e.g to read bytes and transform them in to some stream of elements (e.g., bytes, strings, lines, etc.). The release action then closes the file once the result Stream terminates, even in case of interruption or errors.
acquire
resource to acquire at start of stream
release
function which returns an effect that releases the resource
def bracketCase[F[_], R](acquire: F[R])(release: (R, ExitCase) => F[Unit]): Stream[F, R]
Like bracket but the release action is passed an ExitCase[Throwable].
Like bracket but the release action is passed an ExitCase[Throwable].
ExitCase.Canceled is passed to the release action in the event of either stream interruption or overall compiled effect cancelation.
def bracketCaseWeak[F[_], R](acquire: F[R])(release: (R, ExitCase) => F[Unit]): Stream[F, R]
Like bracketCase but no scope is introduced, causing resource finalization to occur at the end of the current scope at the time of acquisition.
def bracketFull[F[_], R](acquire: (Poll[F]) => F[R])(release: (R, ExitCase) => F[Unit])(implicit F: MonadCancel[F, _]): Stream[F, R]
Like bracketCase but the acquire action may be canceled.
def bracketFullWeak[F[_], R](acquire: (Poll[F]) => F[R])(release: (R, ExitCase) => F[Unit])(implicit F: MonadCancel[F, _]): Stream[F, R]
Like bracketFull but no scope is introduced, causing resource finalization to occur at the end of the current scope at the time of acquisition.
def bracketWeak[F[_], R](acquire: F[R])(release: (R) => F[Unit]): Stream[F, R]
Like bracket but no scope is introduced, causing resource finalization to occur at the end of the current scope at the time of acquisition.
def chunk[F[x] >: Pure[x], O](os: Chunk[O]): Stream[F, O]
Creates a pure stream that emits the elements of the supplied chunk.
Creates a pure stream that emits the elements of the supplied chunk.
Example:
1. scala> Stream.chunk(Chunk(1,2,3)).toList res0: List[Int] = List(1, 2, 3)
def clone(): AnyRef
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.CloneNotSupportedException]) @IntrinsicCandidate() @native()
def constant[F[x] >: Pure[x], O](o: O, chunkSize: Int = 256): Stream[F, O]
Creates an infinite pure stream that always returns the supplied value.
Creates an infinite pure stream that always returns the supplied value.
Elements are emitted in finite chunks with chunkSize number of elements.
Example:
1. scala> Stream.constant(0).take(5).toList res0: List[Int] = List(0, 0, 0, 0, 0)
implicit def deferInstance[F[_]]: Defer[[β$26$]Stream[F, β$26$]]
Defer instance for Stream
def duration[F[_]](implicit F: Clock[F]): Stream[F, FiniteDuration]
A continuous stream of the elapsed time, computed using System.nanoTime.
A continuous stream of the elapsed time, computed using System.nanoTime. Note that the actual granularity of these elapsed times depends on the OS, for instance the OS may only update the current time every ten milliseconds or so.
def emit[F[x] >: Pure[x], O](o: O): Stream[F, O]
Creates a singleton pure stream that emits the supplied value.
Creates a singleton pure stream that emits the supplied value.
Example:
1. scala> Stream.emit(0).toList res0: List[Int] = List(0)
def emits[F[x] >: Pure[x], O](os: Seq[O]): Stream[F, O]
Creates a pure stream that emits the supplied values.
Creates a pure stream that emits the supplied values.
Example:
1. scala> Stream.emits(List(1, 2, 3)).toList res0: List[Int] = List(1, 2, 3)
val empty: Stream[Pure, Nothing]
Empty pure stream.
final def eq(arg0: AnyRef): Boolean
Definition Classes
AnyRef
def equals(arg0: AnyRef): Boolean
Definition Classes
AnyRef → Any
def eval[F[_], O](fo: F[O]): Stream[F, O]
Creates a single element stream that gets its value by evaluating the supplied effect.
Creates a single element stream that gets its value by evaluating the supplied effect. If the effect fails, the returned stream fails.
Use attemptEval instead if a failure while evaluating the effect should be emitted as a value.
Example:
1. scala> import cats.effect.SyncIO scala> Stream.eval(SyncIO(10)).compile.toVector.unsafeRunSync() res0: Vector[Int] = Vector(10) scala> Stream.eval(SyncIO(throw new RuntimeException)).covaryOutput[Int].compile.toVector.attempt.unsafeRunSync() res1: Either[Throwable,Vector[Int]] = Left(java.lang.RuntimeException)
def evalSeq[F[_], S[A] <: Seq[A], O](fo: F[S[O]]): Stream[F, O]
Like evals, but lifts any Seq in the effect.
def evalUnChunk[F[_], O](fo: F[Chunk[O]]): Stream[F, O]
Like eval but resulting chunk is flatten efficiently.
def evals[F[_], S[_], O](fo: F[S[O]])(implicit arg0: Foldable[S]): Stream[F, O]
Like eval, but lifts a foldable structure.
def every[F[_]](d: FiniteDuration)(implicit clock: Clock[F], F: Functor[F]): Stream[F, Boolean]
A continuous stream which is true after d, 2d, 3d... elapsed duration, and false otherwise.
A continuous stream which is true after d, 2d, 3d... elapsed duration, and false otherwise. If you'd like a 'discrete' stream that will actually block until d has elapsed, use awakeEvery instead.
def exec[F[_]](action: F[Unit]): Stream[F, Nothing]
As a result, the returned stream emits no elements and hence has output type Nothing.
As a result, the returned stream emits no elements and hence has output type Nothing.
Example:
1. scala> import cats.effect.SyncIO scala> Stream.exec(SyncIO(println("Ran"))).covaryOutput[Int].compile.toVector.unsafeRunSync() res0: Vector[Int] = Vector()
def fixedDelay[F[_]](period: FiniteDuration)(implicit t: Temporal[F]): Stream[F, Unit]
Light weight alternative to fixedRate that sleeps for duration d before each pulled element.
Light weight alternative to fixedRate that sleeps for duration d before each pulled element.
Behavior differs from fixedRate because the sleep between elements occurs after the next element is pulled whereas fixedRate accounts for the time it takes to process the emitted unit. This difference can roughly be thought of as the difference between scheduleWithFixedDelay and scheduleAtFixedRate in java.util.concurrent.Scheduler.
Alias for sleep(period).repeat.
def fixedRate[F[_]](period: FiniteDuration, dampen: Boolean)(implicit F: Temporal[F]): Stream[F, Unit]
Discrete stream that emits a unit every d.
Discrete stream that emits a unit every d.
See fixedDelay for an alternative that sleeps d between elements.
This operation differs in that the time between ticks should roughly be equal to the specified period, regardless of how much time it takes to process that tick downstream. For example, with a 1 second period and a task that takes 100ms, the task would run at timestamps, 1s, 2s, 3s, etc. when using fixedRate >> task whereas it would run at timestamps 1s, 2.1s, 3.2s, etc. when using fixedDelay >> task.
In the case where task processing takes longer than a single period, 1 or more ticks are immediately emitted to "catch-up". The dampen parameter controls whether a single tick is emitted or whether one per missed period is emitted.
period
period between emits of the resulting stream
dampen
true if a single unit should be emitted when multiple periods have passed since last execution, false if a unit for each period should be emitted
def fixedRate[F[_]](period: FiniteDuration)(implicit t: Temporal[F]): Stream[F, Unit]
Discrete stream that emits a unit every d, with missed period ticks dampened.
Discrete stream that emits a unit every d, with missed period ticks dampened.
See fixedDelay for an alternative that sleeps d between elements.
period
duration between emits of the resulting stream
def fixedRateStartImmediately[F[_]](period: FiniteDuration, dampen: Boolean)(implicit F: Temporal[F]): Stream[F, Unit]
Discrete stream that emits a unit every d.
Discrete stream that emits a unit every d.
Unlike fixedRate, it doesn't wait for d before emitting the first unit.
period
duration between emits of the resulting stream
dampen
true if a single unit should be emitted when multiple periods have passed since last execution, false if a unit for each period should be emitted
def fixedRateStartImmediately[F[_]](period: FiniteDuration)(implicit F: Temporal[F]): Stream[F, Unit]
Discrete stream that emits a unit every d, with missed period ticks dampened.
Discrete stream that emits a unit every d, with missed period ticks dampened.
Unlike fixedRate, it doesn't wait for d before emitting the first unit.
period
duration between emits of the resulting stream
def foldable[F[x] >: Pure[x], G[_], O](os: G[O])(implicit arg0: Foldable[G]): Stream[F, O]
Like emits, but works for any G that has a Foldable instance.
def force[F[_], A](f: F[Stream[F, A]]): Stream[F, A]
Lifts an effect that generates a stream in to a stream.
Lifts an effect that generates a stream in to a stream. Alias for eval(f).flatMap(_).
Example:
1. scala> import cats.effect.SyncIO scala> Stream.force(SyncIO(Stream(1,2,3).covary[SyncIO])).compile.toVector.unsafeRunSync() res0: Vector[Int] = Vector(1, 2, 3)
def fromAutoCloseable[F[_], O <: AutoCloseable](fo: F[O])(implicit arg0: Sync[F]): Stream[F, O]
Converts the supplied java.lang.AutoCloseable into a singleton stream.
def fromAutoCloseableWeak[F[_], O <: AutoCloseable](fo: F[O])(implicit arg0: Sync[F]): Stream[F, O]
Like fromAutoCloseable but does not introduce a scope, allowing finalization to occur after subsequent appends or other scope-preserving transformations.
Like fromAutoCloseable but does not introduce a scope, allowing finalization to occur after subsequent appends or other scope-preserving transformations.
Scopes can be manually introduced via Stream#scope if desired.
def fromBlockingIterator[F[_]]: PartiallyAppliedFromBlockingIterator[F]
Lifts an iterator into a Stream, shifting any interaction with the iterator to the blocking pool.

def fromEither[F[_]]: PartiallyAppliedFromEither[F]

Lifts an Either[Throwable, A] to an effectful Stream.

Example:

scala> import cats.effect.SyncIO, scala.util.Try
scala> Stream.fromEither[SyncIO](Right(42)).compile.toList.unsafeRunSync()
res0: List[Int] = List(42)
scala> Try(Stream.fromEither[SyncIO](Left(new RuntimeException)).compile.toList.unsafeRunSync())
res1: Try[List[Nothing]] = Failure(java.lang.RuntimeException)

def fromIterator[F[_]]: PartiallyAppliedFromIterator[F]
Lifts an iterator into a Stream.

def fromOption[F[_]]: PartiallyAppliedFromOption[F]

Lifts an Option[A] to an effectful Stream.

Example:

scala> import cats.effect.SyncIO
scala> Stream.fromOption[SyncIO](Some(42)).compile.toList.unsafeRunSync()
res0: List[Int] = List(42)
scala> Stream.fromOption[SyncIO](None).compile.toList.unsafeRunSync()
res1: List[Nothing] = List()

def fromQueueNoneTerminated[F[_], A](queue: Queue[F, Option[A]], limit: Int)(implicit arg0: Functor[F]): Stream[F, A]
Returns a stream of elements from the supplied queue.
Returns a stream of elements from the supplied queue.
The stream terminates upon dequeuing a None.
All elements that are available, up to the specified limit, are dequeued and emitted as a single chunk.
def fromQueueNoneTerminated[F[_], A](queue: QueueSource[F, Option[A]], limit: Int = Int.MaxValue)(implicit arg0: Functor[F]): Stream[F, A]
Returns a stream of elements from the supplied queue.
Returns a stream of elements from the supplied queue.
The stream terminates upon dequeuing a None.
All elements that are available, up to the specified limit, are dequeued and emitted as a single chunk.
Annotations
@nowarn()
def fromQueueNoneTerminatedChunk[F[_], A](queue: Queue[F, Option[Chunk[A]]], limit: Int): Stream[F, A]
Returns a stream of elements from the supplied queue.
Returns a stream of elements from the supplied queue.
The stream terminates upon dequeuing a None.
All elements that are available, up to the specified limit, are dequeued and emitted as a single chunk.
def fromQueueNoneTerminatedChunk[F[_], A](queue: QueueSource[F, Option[Chunk[A]]], limit: Int = Int.MaxValue): Stream[F, A]
Returns a stream of elements from the supplied queue.
Returns a stream of elements from the supplied queue.
The stream terminates upon dequeuing a None.
All elements that are available, up to the specified limit, are dequeued and emitted as a single chunk.
def fromQueueUnterminated[F[_], A](queue: Queue[F, A], limit: Int)(implicit arg0: Functor[F]): Stream[F, A]
Returns a stream of elements from the supplied queue.
Returns a stream of elements from the supplied queue.
All elements that are available, up to the specified limit, are dequeued and emitted as a single chunk.
def fromQueueUnterminated[F[_], A](queue: QueueSource[F, A], limit: Int = Int.MaxValue)(implicit F: Functor[F]): Stream[F, A]
Returns a stream of elements from the supplied queue.
Returns a stream of elements from the supplied queue.
All elements that are available, up to the specified limit, are dequeued and emitted as a single chunk.
def fromQueueUnterminatedChunk[F[_], A](queue: Queue[F, Chunk[A]], limit: Int)(implicit arg0: Functor[F]): Stream[F, A]
Returns a stream of elements from the supplied queue.
Returns a stream of elements from the supplied queue.
All elements that are available, up to the specified limit, are dequeued and emitted as a single chunk.
def fromQueueUnterminatedChunk[F[_], A](queue: QueueSource[F, Chunk[A]], limit: Int = Int.MaxValue)(implicit arg0: Functor[F]): Stream[F, A]
Returns a stream of elements from the supplied queue.
Returns a stream of elements from the supplied queue.
All elements that are available, up to the specified limit, are dequeued and emitted as a single chunk.
implicit def functionKInstance[F[_]]: ~>[F, [β$22$]Stream[F, β$22$]]
FunctionK instance for F ~> Stream[F, *]
FunctionK instance for F ~> Stream[F, *]
Example:
1. scala> import cats.Id scala> Stream.functionKInstance[Id](42).compile.toList res0: cats.Id[List[Int]] = List(42)

implicit def functorFilterInstance[F[_]]: FunctorFilter[[β$18$]Stream[F, β$18$]]

FunctorFilter instance for Stream.

Example:

scala> import cats.syntax.all._, scala.util._
scala> Stream("1", "2", "NaN").mapFilter(s => Try(s.toInt).toOption).toList
res0: List[Int] = List(1, 2)

final def getClass(): Class[_ <: AnyRef]
Definition Classes
AnyRef → Any
Annotations
@IntrinsicCandidate() @native()
def hashCode(): Int
Definition Classes
AnyRef → Any
Annotations
@IntrinsicCandidate() @native()
final def isInstanceOf[T0]: Boolean
Definition Classes
Any
def iterable[F[x] >: Pure[x], A](os: Iterable[A]): Stream[F, A]
Like emits, but works for any class that extends Iterable
def iterate[F[x] >: Pure[x], A](start: A)(f: (A) => A): Stream[F, A]
An infinite Stream that repeatedly applies a given function to a start value.
An infinite Stream that repeatedly applies a given function to a start value. start is the first value emitted, followed by f(start), then f(f(start)), and so on.
Example:
1. scala> Stream.iterate(0)(_ + 1).take(10).toList res0: List[Int] = List(0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
def iterateEval[F[_], A](start: A)(f: (A) => F[A]): Stream[F, A]
Like iterate, but takes an effectful function for producing the next state.
Like iterate, but takes an effectful function for producing the next state. start is the first value emitted.
Example:
1. scala> import cats.effect.SyncIO scala> Stream.iterateEval(0)(i => SyncIO(i + 1)).take(10).compile.toVector.unsafeRunSync() res0: Vector[Int] = Vector(0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
implicit def monadErrorInstance[F[_]](implicit ev: ApplicativeError[F, Throwable]): MonadError[[β$12$]Stream[F, β$12$], Throwable]
MonadError instance for Stream.
MonadError instance for Stream.
Example:
1. scala> import cats.syntax.all._ scala> Stream(1, -2, 3).fproduct(_.abs).toList res0: List[(Int, Int)] = List((1,1), (-2,2), (3,3))
implicit def monadInstance[F[_]]: Monad[[β$28$]Stream[F, β$28$]]
Definition Classes
StreamLowPriority
implicit def monoidInstance[F[_], O]: Monoid[Stream[F, O]]
Monoid instance for Stream.
implicit def monoidKInstance[F[_]]: MonoidK[[β$24$]Stream[F, β$24$]]
final def ne(arg0: AnyRef): Boolean
Definition Classes
AnyRef
def never[F[_]](implicit F: Spawn[F]): Stream[F, Nothing]
A stream that never emits and never terminates.
final def notify(): Unit
Definition Classes
AnyRef
Annotations
@IntrinsicCandidate() @native()
final def notifyAll(): Unit
Definition Classes
AnyRef
Annotations
@IntrinsicCandidate() @native()

def raiseError[F[_]](e: Throwable)(implicit arg0: RaiseThrowable[F]): Stream[F, Nothing]

Creates a stream that, when run, fails with the supplied exception.

The F type must be explicitly provided (e.g., via raiseError[IO] or raiseError[Fallible]).

Example:

scala> import cats.effect.SyncIO
scala> Stream.raiseError[Fallible](new RuntimeException).toList
res0: Either[Throwable,List[Nothing]] = Left(java.lang.RuntimeException)
scala> Stream.raiseError[SyncIO](new RuntimeException).covaryOutput[Int].compile.drain.attempt.unsafeRunSync()
res0: Either[Throwable,Unit] = Left(java.lang.RuntimeException)

def range[F[x] >: Pure[x], O](start: O, stopExclusive: O, step: O)(implicit arg0: Numeric[O]): Stream[F, O]
Lazily produce the sequence [start, start + step, start + 2 * step, ..., stopExclusive).
Lazily produce the sequence [start, start + step, start + 2 * step, ..., stopExclusive). If you want to produce the sequence in one chunk, instead of lazily, use emits(start until stopExclusive by step).
Example:
1. scala> Stream.range(10, 20, 2).toList res0: List[Int] = List(10, 12, 14, 16, 18)
def range[F[x] >: Pure[x], O](start: O, stopExclusive: O)(implicit arg0: Numeric[O]): Stream[F, O]
Lazily produces the sequence [start, start + 1, start + 2, ..., stopExclusive).
Lazily produces the sequence [start, start + 1, start + 2, ..., stopExclusive). If you want to produce the sequence in one chunk, instead of lazily, use emits(start until stopExclusive).
Example:
1. scala> Stream.range(10, 20).toList res0: List[Int] = List(10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
def ranges[F[x] >: Pure[x]](start: Int, stopExclusive: Int, size: Int): Stream[F, (Int, Int)]
Lazily produce a sequence of nonoverlapping ranges, where each range contains size integers, assuming the upper bound is exclusive.
Lazily produce a sequence of nonoverlapping ranges, where each range contains size integers, assuming the upper bound is exclusive. Example: ranges(0, 1000, 10) results in the pairs (0, 10), (10, 20), (20, 30) ... (990, 1000)
Note: The last emitted range may be truncated at stopExclusive. For instance, ranges(0,5,4) results in (0,4), (4,5).
Example:
1. scala> Stream.ranges(0, 20, 5).toList res0: List[(Int,Int)] = List((0,5), (5,10), (10,15), (15,20))
Exceptions thrown
IllegalArgumentException if size <= 0
def repeatEval[F[_], O](fo: F[O]): Stream[F, O]
Alias for eval(fo).repeat.
def resource[F[_], O](r: Resource[F, O])(implicit F: MonadCancel[F, _]): Stream[F, O]
Converts the supplied resource into a singleton stream.
def resourceK[F[_]](implicit F: MonadCancel[F, _]): ~>[[β$0$]Resource[F, β$0$], [β$1$]Stream[F, β$1$]]
Same as resource, but expressed as a FunctionK.
def resourceWeak[F[_], O](r: Resource[F, O])(implicit F: MonadCancel[F, _]): Stream[F, O]
Like resource but does not introduce a scope, allowing finalization to occur after subsequent appends or other scope-preserving transformations.
Like resource but does not introduce a scope, allowing finalization to occur after subsequent appends or other scope-preserving transformations.
Scopes can be manually introduced via Stream#scope if desired.
def resourceWeakK[F[_]](implicit F: MonadCancel[F, _]): ~>[[β$4$]Resource[F, β$4$], [β$5$]Stream[F, β$5$]]
Same as resourceWeak, but expressed as a FunctionK.
def retry[F[_], O](fo: F[O], delay: FiniteDuration, nextDelay: (FiniteDuration) => FiniteDuration, maxAttempts: Int, retriable: (Throwable) => Boolean = scala.util.control.NonFatal.apply)(implicit arg0: Temporal[F], arg1: RaiseThrowable[F]): Stream[F, O]
Retries fo on failure, returning a singleton stream with the result of fo as soon as it succeeds.
Retries fo on failure, returning a singleton stream with the result of fo as soon as it succeeds.
delay
Duration of delay before the first retry
nextDelay
Applied to the previous delay to compute the next, e.g. to implement exponential backoff
maxAttempts
Number of attempts before failing with the latest error, if fo never succeeds
retriable
Function to determine whether a failure is retriable or not, defaults to retry every NonFatal. A failed stream is immediately returned when a non-retriable failure is encountered
def sleep[F[_]](d: FiniteDuration)(implicit t: Temporal[F]): Stream[F, Unit]
A single-element Stream that waits for the duration d before emitting unit.
def sleep_[F[_]](d: FiniteDuration)(implicit t: Temporal[F]): Stream[F, Nothing]
Alias for sleep(d).drain.
Alias for sleep(d).drain. Often used in conjunction with ++ (i.e., sleep_(..) ++ s) as a more performant version of sleep(..) >> s.
def supervise[F[_], A](fa: F[A])(implicit F: Spawn[F]): Stream[F, Fiber[F, Throwable, A]]
Starts the supplied task and cancels it as finalization of the returned stream.
def suspend[F[_], O](s: => Stream[F, O]): Stream[F, O]
Returns a stream that evaluates the supplied by-name each time the stream is used, allowing use of a mutable value in stream computations.
Returns a stream that evaluates the supplied by-name each time the stream is used, allowing use of a mutable value in stream computations.
Note: it's generally easier to reason about such computations using effectful values. That is, allocate the mutable value in an effect and then use Stream.eval(fa).flatMap { a => ??? }.
Example:
1. scala> Stream.suspend { | val digest = java.security.MessageDigest.getInstance("SHA-256") | val bytes: Stream[Pure,Byte] = ??? | bytes.chunks.fold(digest) { (d,c) => d.update(c.toBytes.values); d } | }
final def synchronized[T0](arg0: => T0): T0
Definition Classes
AnyRef
def toString(): String
Definition Classes
AnyRef → Any
def unfold[F[x] >: Pure[x], S, O](s: S)(f: (S) => Option[(O, S)]): Stream[F, O]
Creates a stream by successively applying f until a None is returned, emitting each output O and using each output S as input to the next invocation of f.
Creates a stream by successively applying f until a None is returned, emitting each output O and using each output S as input to the next invocation of f.
Example:
1. scala> Stream.unfold(0)(i => if (i < 5) Some(i -> (i+1)) else None).toList res0: List[Int] = List(0, 1, 2, 3, 4)
def unfoldChunk[F[x] >: Pure[x], S, O](s: S)(f: (S) => Option[(Chunk[O], S)]): Stream[F, O]
Like unfold but each invocation of f provides a chunk of output.
Like unfold but each invocation of f provides a chunk of output.
Example:
1. scala> Stream.unfoldChunk(0)(i => if (i < 5) Some(Chunk.from(List.fill(i)(i)) -> (i+1)) else None).toList res0: List[Int] = List(1, 2, 2, 3, 3, 3, 4, 4, 4, 4)
def unfoldChunkEval[F[_], S, O](s: S)(f: (S) => F[Option[(Chunk[O], S)]]): Stream[F, O]
Like unfoldChunk, but takes an effectful function.
def unfoldEval[F[_], S, O](s: S)(f: (S) => F[Option[(O, S)]]): Stream[F, O]
Like unfold, but takes an effectful function.
def unfoldLoop[F[x] <: Pure[x], S, O](start: S)(f: (S) => (O, Option[S])): Stream[F, O]
Creates a stream by successively applying f to a S, emitting each output O and using each output S as input to the next invocation of f if it is Some, or terminating on None
Creates a stream by successively applying f to a S, emitting each output O and using each output S as input to the next invocation of f if it is Some, or terminating on None
Example:
1. scala> Stream.unfoldLoop(0)(i => (i, if (i < 5) Some(i+1) else None)).toList res0: List[Int] = List(0, 1, 2, 3, 4, 5)
def unfoldLoopEval[F[_], S, O](start: S)(f: (S) => F[(O, Option[S])]): Stream[F, O]
Like unfoldLoop, but takes an effectful function.
val unit: Stream[Pure, Unit]
A pure stream that just emits the unit value once and ends.
final def wait(arg0: Long, arg1: Int): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
final def wait(arg0: Long): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException]) @native()
final def wait(): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
object PartiallyAppliedFromIterator extends PartiallyAppliedFromBlockingIteratorCrossCompat

Deprecated Value Members

def eval_[F[_], A](fa: F[A]): Stream[F, Nothing]
Creates a stream that evaluates the supplied fa for its effect, discarding the output value.
Creates a stream that evaluates the supplied fa for its effect, discarding the output value. As a result, the returned stream emits no elements and hence has output type Nothing.
Alias for eval(fa).drain.
Annotations
@deprecated
Deprecated
(Since version 2.5.0) Use exec if passing an F[Unit] or eval(fa).drain if passing an F[A]
def finalize(): Unit
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.Throwable]) @Deprecated
Deprecated
(Since version 9)

Packages

Stream

Companion class Stream

object Stream extends StreamLowPriority

Type Members

Value Members

Deprecated Value Members

Inherited from StreamLowPriority

Inherited from AnyRef

Inherited from Any

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Packages

Stream

Companion class Stream

object Stream extends StreamLowPriority

Type Members

Value Members

Deprecated Value Members

Inherited from StreamLowPriority

Inherited from AnyRef

Inherited from Any

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Stream