Fiber API Reference

Alternatives

orElse

Since v2.0.0

Returns a fiber that prefers this fiber, but falls back to the that one when this one fails. Interrupting the returned fiber will interrupt both fibers, sequentially, from left to right.

Signature

declare const orElse: {
  <A2, E2>(that: Fiber<A2, E2>): <A, E>(self: Fiber<A, E>) => Fiber<A2 | A, E2 | E>;
  <A, E, A2, E2>(self: Fiber<A, E>, that: Fiber<A2, E2>): Fiber<A | A2, E | E2>;
}

orElseEither

Since v2.0.0

Returns a fiber that prefers this fiber, but falls back to the that one when this one fails. Interrupting the returned fiber will interrupt both fibers, sequentially, from left to right.

Signature

declare const orElseEither: {
  <A2, E2>(that: Fiber<A2, E2>): <A, E>(self: Fiber<A, E>) => Fiber<Either<A2, A>, E2 | E>;
  <A, E, A2, E2>(self: Fiber<A, E>, that: Fiber<A2, E2>): Fiber<Either<A2, A>, E | E2>;
}

Constructors

all

Since v2.0.0

Collects all fibers into a single fiber producing an in-order list of the results.

Signature

declare const all: <A, E>(fibers: Iterable<Fiber<A, E>>) => Fiber<ReadonlyArray<A>, E>

done

Since v2.0.0

A fiber that is done with the specified Exit value.

Signature

declare const done: <A, E>(exit: Exit.Exit<A, E>) => Fiber<A, E>

fail

Since v2.0.0

A fiber that has already failed with the specified value.

Signature

declare const fail: <E>(error: E) => Fiber<never, E>

failCause

Since v2.0.0

Creates a Fiber that has already failed with the specified cause.

Signature

declare const failCause: <E>(cause: Cause.Cause<E>) => Fiber<never, E>

interrupted

Since v2.0.0

Constructrs a Fiber that is already interrupted.

Signature

declare const interrupted: (fiberId: FiberId.FiberId) => Fiber<never>

never

Since v2.0.0

A fiber that never fails or succeeds.

Signature

declare const never: Fiber<never>

roots

Since v2.0.0

Returns a chunk containing all root fibers.

Signature

declare const roots: Effect.Effect<Array<RuntimeFiber<any, any>>>

succeed

Since v2.0.0

Returns a fiber that has already succeeded with the specified value.

Signature

declare const succeed: <A>(value: A) => Fiber<A>

unsafeRoots

Since v2.0.0

Returns a chunk containing all root fibers.

Signature

declare const unsafeRoots: (_: void) => Array<RuntimeFiber<any, any>>

Conversions

fromEffect

Since v2.0.0

Lifts an Effect into a Fiber.

Signature

declare const fromEffect: <A, E>(effect: Effect.Effect<A, E>) => Effect.Effect<Fiber<A, E>>

Joins the fiber, which suspends the joining fiber until the result of the fiber has been determined. Attempting to join a fiber that has erred will result in a catchable error. Joining an interrupted fiber will result in an "inner interruption" of this fiber, unlike interruption triggered by another fiber, "inner interruption" can be caught and recovered.

Signature

declare const join: <A, E>(self: Fiber<A, E>) => Effect.Effect<A, E>

joinAll

Since v2.0.0

Joins all fibers, awaiting their successful completion. Attempting to join a fiber that has erred will result in a catchable error, if that error does not result from interruption.

Signature

declare const joinAll: <A, E>(fibers: Iterable<Fiber<A, E>>) => Effect.Effect<Array<A>, E>

pretty

Since v2.0.0

Pretty-prints a RuntimeFiber.

Signature

declare const pretty: <A, E>(self: RuntimeFiber<A, E>) => Effect.Effect<string>

scoped

Since v2.0.0

Converts this fiber into a scoped effect. The fiber is interrupted when the scope is closed.

Signature

declare const scoped: <A, E>(self: Fiber<A, E>) => Effect.Effect<Fiber<A, E>, never, Scope.Scope>

Folding

match

Since v2.0.0

Folds over the Fiber or RuntimeFiber.

Signature

declare const match: {
  <A, E, Z>(options: {
    readonly onFiber: (fiber: Fiber<A, E>) => Z;
    readonly onRuntimeFiber: (fiber: RuntimeFiber<A, E>) => Z;
  }): (self: Fiber<A, E>) => Z;
  <A, E, Z>(self: Fiber<A, E>, options: {
    readonly onFiber: (fiber: Fiber<A, E>) => Z;
    readonly onRuntimeFiber: (fiber: RuntimeFiber<A, E>) => Z;
  }): Z;
}

Getters

children

Since v2.0.0

Retrieves the immediate children of the fiber.

Signature

declare const children: <A, E>(self: Fiber<A, E>) => Effect.Effect<Array<RuntimeFiber<any, any>>>

id

Since v2.0.0

The identity of the fiber.

Signature

declare const id: <A, E>(self: Fiber<A, E>) => FiberId.FiberId

poll

Since v2.0.0

Tentatively observes the fiber, but returns immediately if it is not already done.

Signature

declare const poll: <A, E>(self: Fiber<A, E>) => Effect.Effect<Option.Option<Exit.Exit<A, E>>>

status

Since v2.0.0

Returns the FiberStatus of a RuntimeFiber.

Signature

declare const status: <A, E>(self: RuntimeFiber<A, E>) => Effect.Effect<FiberStatus.FiberStatus>

Instances

Order

Since v2.0.0

Signature

declare const Order: order.Order<RuntimeFiber<unknown, unknown>>

Interruption

interrupt

Since v2.0.0

Interrupts the fiber from whichever fiber is calling this method. If the fiber has already exited, the returned effect will resume immediately. Otherwise, the effect will resume when the fiber exits.

Signature

declare const interrupt: <A, E>(self: Fiber<A, E>) => Effect.Effect<Exit.Exit<A, E>>

interruptAll

Since v2.0.0

Interrupts all fibers, awaiting their interruption.

Signature

declare const interruptAll: (fibers: Iterable<Fiber<any, any>>) => Effect.Effect<void>

interruptAllAs

Since v2.0.0

Interrupts all fibers as by the specified fiber, awaiting their interruption.

Signature

declare const interruptAllAs: {
  (fiberId: FiberId): (fibers: Iterable<Fiber<any, any>>) => Effect<void>;
  (fibers: Iterable<Fiber<any, any>>, fiberId: FiberId): Effect<void>;
}

interruptAs

Since v2.0.0

Interrupts the fiber as if interrupted from the specified fiber. If the fiber has already exited, the returned effect will resume immediately. Otherwise, the effect will resume when the fiber exits.

Signature

declare const interruptAs: {
  (fiberId: FiberId): <A, E>(self: Fiber<A, E>) => Effect<Exit<A, E>>;
  <A, E>(self: Fiber<A, E>, fiberId: FiberId): Effect<Exit<A, E>>;
}

interruptAsFork

Since v2.0.0

Interrupts the fiber as if interrupted from the specified fiber. If the fiber has already exited, the returned effect will resume immediately. Otherwise, the effect will resume when the fiber exits.

Signature

declare const interruptAsFork: {
  (fiberId: FiberId): <A, E>(self: Fiber<A, E>) => Effect<void>;
  <A, E>(self: Fiber<A, E>, fiberId: FiberId): Effect<void>;
}

interruptFork

Since v2.0.0

Interrupts the fiber from whichever fiber is calling this method. The interruption will happen in a separate daemon fiber, and the returned effect will always resume immediately without waiting.

Signature

declare const interruptFork: <A, E>(self: Fiber<A, E>) => Effect.Effect<void>

Mapping

map

Since v2.0.0

Maps over the value the Fiber computes.

Signature

declare const map: {
  <A, B>(f: (a: A) => B): <E>(self: Fiber<A, E>) => Fiber<B, E>;
  <A, E, B>(self: Fiber<A, E>, f: (a: A) => B): Fiber<B, E>;
}

mapEffect

Since v2.0.0

Effectually maps over the value the fiber computes.

Signature

declare const mapEffect: {
  <A, A2, E2>(f: (a: A) => Effect<A2, E2>): <E>(self: Fiber<A, E>) => Fiber<A2, E2 | E>;
  <A, E, A2, E2>(self: Fiber<A, E>, f: (a: A) => Effect<A2, E2>): Fiber<A2, E | E2>;
}

mapFiber

Since v2.0.0

Passes the success of this fiber to the specified callback, and continues with the fiber that it returns.

Signature

declare const mapFiber: {
  <E, E2, A, B>(f: (a: A) => Fiber<B, E2>): (self: Fiber<A, E>) => Effect<Fiber<B, E | E2>>;
  <A, E, E2, B>(self: Fiber<A, E>, f: (a: A) => Fiber<B, E2>): Effect<Fiber<B, E | E2>>;
}

Models

Fiber

interface

Since v2.0.0

A fiber is a lightweight thread of execution that never consumes more than a whole thread (but may consume much less, depending on contention and asynchronicity). Fibers are spawned by forking effects, which run concurrently with the parent effect.

Fibers can be joined, yielding their result to other fibers, or interrupted, which terminates the fiber, safely releasing all resources.

Signature

interface Fiber<out A, out E = never> extends Effect<A, E>, Variance<A, E> {
  readonly [ignoreSymbol]?: FiberUnifyIgnore;
  readonly [typeSymbol]?: unknown;
  readonly [unifySymbol]?: FiberUnify<Fiber<A, E>>;
  readonly await: Effect<Exit<A, E>>;
  readonly children: Effect<Array<Runtime<any, any>>>;
  readonly inheritAll: Effect<void>;
  readonly poll: Effect<Option<Exit<A, E>>>;
  id(): FiberId;
  interruptAsFork(fiberId: FiberId): Effect<void>;
}

FiberUnify

interface

Since v3.8.0

Signature

interface FiberUnify<A extends {
  [typeSymbol]?: any;
}> extends EffectUnify<A> {
  Fiber?: () => A[typeof typeSymbol] extends Fiber<A0, E0> | _ ? Fiber<A0, E0> : never;
}

FiberUnifyIgnore

interface

Since v3.8.0

Signature

interface FiberUnifyIgnore extends EffectUnifyIgnore {
  Effect?: true;
}

RuntimeFiber

interface

Since v2.0.0

A runtime fiber that is executing an effect. Runtime fibers have an identity and a trace.

Signature

interface RuntimeFiber<out A, out E = never> extends Fiber<A, E>, RuntimeVariance<A, E> {
  readonly [ignoreSymbol]?: RuntimeFiberUnifyIgnore;
  readonly [typeSymbol]?: unknown;
  readonly [unifySymbol]?: RuntimeFiberUnify<RuntimeFiber<A, E>>;
  readonly runtimeFlags: Effect<RuntimeFlags>;
  readonly status: Effect<FiberStatus>;
  currentContext: Context<never>;
  currentDefaultServices: Context<DefaultServices>;
  currentOpCount: number;
  currentScheduler: Scheduler;
  currentSpan: AnySpan | undefined;
  currentSupervisor: Supervisor<unknown>;
  currentTracer: Tracer;
  addObserver(observer: (exit: Exit<A, E>) => void): void;
  getFiberRef<X>(fiberRef: FiberRef<X>): X;
  getFiberRefs(): FiberRefs;
  id(): Runtime;
  removeObserver(observer: (exit: Exit<A, E>) => void): void;
  unsafeInterruptAsFork(fiberId: FiberId): void;
  unsafePoll(): Exit<A, E> | null;
}

RuntimeFiberUnify

interface

Since v3.8.0

Signature

interface RuntimeFiberUnify<A extends {
  [typeSymbol]?: any;
}> extends FiberUnify<A> {
  RuntimeFiber?: () => A[typeof typeSymbol] extends RuntimeFiber<A0, E0> | _ ? RuntimeFiber<A0, E0> : never;
}

RuntimeFiberUnifyIgnore

interface

Since v3.8.0

Signature

interface RuntimeFiberUnifyIgnore extends FiberUnifyIgnore {
  Fiber?: true;
}

Other

await

Signature

declare const await: <A, E>(self: Fiber<A, E>) => Effect.Effect<Exit.Exit<A, E>>

Fiber

Since v2.0.0

void

Signature

declare const void: Fiber<void>

Refinements

isFiber

Since v2.0.0

Returns true if the specified value is a Fiber, false otherwise.

Signature

declare const isFiber: (u: unknown) => u is Fiber<unknown, unknown>

isRuntimeFiber

Since v2.0.0

Returns true if the specified Fiber is a RuntimeFiber, false otherwise.

Signature

declare const isRuntimeFiber: <A, E>(self: Fiber<A, E>) => self is RuntimeFiber<A, E>

Symbols

FiberTypeId

Since v2.0.0

Signature

declare const FiberTypeId: unique symbol

FiberTypeId

type

Since v2.0.0

Signature

type FiberTypeId = typeof FiberTypeId

RuntimeFiberTypeId

Since v2.0.0

Signature

declare const RuntimeFiberTypeId: unique symbol

RuntimeFiberTypeId

type

Since v2.0.0

Signature

type RuntimeFiberTypeId = typeof RuntimeFiberTypeId

Utilities

getCurrentFiber

Since v2.0.0

Gets the current fiber if one is running.

Signature

declare const getCurrentFiber: () => Option.Option<RuntimeFiber<any, any>>

Zipping

zip

Since v2.0.0

Zips this fiber and the specified fiber together, producing a tuple of their output.

Signature

declare const zip: {
  <A2, E2>(that: Fiber<A2, E2>): <A, E>(self: Fiber<A, E>) => Fiber<[A, A2], E2 | E>;
  <A, E, A2, E2>(self: Fiber<A, E>, that: Fiber<A2, E2>): Fiber<[A, A2], E | E2>;
}

zipLeft

Since v2.0.0

Same as zip but discards the output of that Fiber.

Signature

declare const zipLeft: {
  <A2, E2>(that: Fiber<A2, E2>): <A, E>(self: Fiber<A, E>) => Fiber<A, E2 | E>;
  <A, E, A2, E2>(self: Fiber<A, E>, that: Fiber<A2, E2>): Fiber<A, E | E2>;
}

zipRight

Since v2.0.0

Same as zip but discards the output of this Fiber.

Signature

declare const zipRight: {
  <A2, E2>(that: Fiber<A2, E2>): <A, E>(self: Fiber<A, E>) => Fiber<A2, E2 | E>;
  <A, E, A2, E2>(self: Fiber<A, E>, that: Fiber<A2, E2>): Fiber<A2, E | E2>;
}

zipWith

Since v2.0.0

Zips this fiber with the specified fiber, combining their results using the specified combiner function. Both joins and interruptions are performed in sequential order from left to right.

Signature

declare const zipWith: {
  <B, E2, A, C>(that: Fiber<B, E2>, f: (a: A, b: B) => C): <E>(self: Fiber<A, E>) => Fiber<C, E2 | E>;
  <A, E, B, E2, C>(self: Fiber<A, E>, that: Fiber<B, E2>, f: (a: A, b: B) => C): Fiber<C, E | E2>;
}