Packages

  • package root
    Definition Classes
    root
  • package h8io
    Definition Classes
    root
  • package stages
    Definition Classes
    h8io
  • package base

    Type aliases used throughout the lib module for describing stage transformations.

    Type aliases used throughout the lib module for describing stage transformations.

    // A decorator is a stage itself: it wraps a Stage[I, O, E] and is one:
val myDecorator: Decorator[String, Int, Nothing] = CompleteIfNone(stage)

// A decoration is the function building it; an alteration is the same with the types free to change:
val myDecoration: Decoration[String, Int, Nothing] = CompleteIfNone(_)
val myAlteration: Alteration[Stage[String, Int, Nothing], Stage[String, Option[Int], Nothing]] = Lift(_)
    Definition Classes
    stages
  • package cats
    Definition Classes
    stages
  • package cycles
    Definition Classes
    stages
  • package operators
    Definition Classes
    stages
  • package projections
    Definition Classes
    stages
  • package std
    Definition Classes
    stages
  • Evolution
  • Stage
  • Status
  • Yield

trait Stage[-I, +O, +E] extends (I) ⇒ Yield[I, O, E]

A single processing unit of a pipeline: a function from an input value to a Yield — an optional output, a Status, and an Evolution that decides what the pipeline looks like for the next run.

Lifecycle

Every stage instance takes exactly one of three paths per pipeline run:

  • applied — apply receives an input value and returns a Yield. It may perform side effects and produce any output, status and evolution it likes.
  • skipped — skip returns the evolution the stage would have returned had it run, without consuming an input. Any stage that takes part in a run but does not process the current input takes this path.
  • failed — apply throws. No Yield, and therefore no Evolution, reaches the caller.

Resource cleanup belongs to the Evolution returned by either of the first two: Evolution.dispose is the exclusive release point, and the stage is permanently unusable afterwards. The failed path is the one case where nobody outside can release anything — there is no evolution to dispose — so a stage that throws must release its own resources before letting the exception escape. The core takes no other part in exception handling; the lib module offers h8io.stages.operators.Safe as a crutch for the simplest, stateless cases. Fatal exceptions are outside this contract.

Composition

~> builds a pipeline out of two stages. When the upstream yields an output, it becomes the downstream's input and the two yields are merged; when it yields nothing, the downstream is not applied for this input — it is skipped and its evolution composed in, so it still evolves in step with the rest of the pipeline.

I

the input type (contravariant)

O

the output type (covariant)

E

the error type (covariant)

Linear Supertypes
(I) ⇒ Yield[I, O, E], AnyRef, Any
Known Subclasses
Alterator, BinaryOperator, Fn, Fruitful, FruitfulStaticStage, LeftProjection, Projection, RightProjection, SAMStage, SafeStage, StaticStage, IOr, Left, Right, Invalid, Valid, Fold, Loop, Reduce, Repeat, And, CompleteIfNone, IAnd, Lift, LocalSoftDeadline, Or, Safe, Left, Right, Left, Right, Unlift, Coalesce, Complete, Const, Countdown, DeadEnd, DeadEnd, GlobalSoftDeadline, Identity, Scan, Swap
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Inherited
  1. Stage
  2. Function1
  3. AnyRef
  4. Any
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Visibility
  1. Public
  2. All

Abstract Value Members

  1. abstract def apply(in: I): Yield[I, O, E]

    Processes in and returns the Yield carrying the optional output, the status and the continuation.

    Processes in and returns the Yield carrying the optional output, the status and the continuation.

    A stage that throws from here must have released its own resources first — see the Lifecycle section above.

    Definition Classes
    Stage → Function1
  2. abstract def skip(): Evolution[I, O, E]

    Returns this stage's Evolution without consuming an input.

    Returns this stage's Evolution without consuming an input.

    Called instead of apply whenever the stage takes part in a run but has nothing to process: the upstream yielded no output, or a binary operator excluded this branch. The evolution must be the one the stage would have returned had it run. Like apply, skip() may perform side effects — a decorator, for instance, may advance or release the inner stage it owns.

Concrete Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##(): Int
    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  4. def andThen[A](g: (Yield[I, O, E]) ⇒ A): (I) ⇒ A
    Definition Classes
    Function1
    Annotations
    @unspecialized()
  5. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  6. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native() @IntrinsicCandidate()
  7. def compose[A](g: (A) ⇒ I): (A) ⇒ Yield[I, O, E]
    Definition Classes
    Function1
    Annotations
    @unspecialized()
  8. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  9. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  10. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
    Annotations
    @native() @IntrinsicCandidate()
  11. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native() @IntrinsicCandidate()
  12. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  13. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  14. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native() @IntrinsicCandidate()
  15. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native() @IntrinsicCandidate()
  16. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  17. def toString(): String
    Definition Classes
    Function1 → AnyRef → Any
  18. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  19. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()
  20. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  21. final def ~>[_O, _E >: E](that: Stage[O, _O, _E]): Stage[I, _O, _E]

    Composes this stage with that, feeding this stage's output into it.

    Composes this stage with that, feeding this stage's output into it. See the Composition section above for what happens when there is no output to feed.

    Annotations
    @inline()

Deprecated Value Members

  1. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] ) @Deprecated
    Deprecated

Inherited from (I) ⇒ Yield[I, O, E]

Inherited from AnyRef

Inherited from Any

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