<K, A, E, XE extends E, XA extends A>(
key: K,
fiber: Fiber.Fiber<XA, XE>,
options?:
| {
readonly onlyIfMissing?: boolean | undefined
readonly propagateInterruption?: boolean | undefined
}
| undefined
): (self: FiberMap<K, A, E>) => void
<K, A, E, XE extends E, XA extends A>(
self: FiberMap<K, A, E>,
key: K,
fiber: Fiber.Fiber<XA, XE>,
options?:
| {
readonly onlyIfMissing?: boolean | undefined
readonly propagateInterruption?: boolean | undefined
}
| undefined
): voidAdds a fiber to the FiberMap under a key using a synchronous, unsafe
mutation.
When to use
Use when an existing forked fiber must be installed under a key immediately and synchronous interruption of the replaced fiber is acceptable.
Details
When the fiber completes, it is removed from the map. If the key already has
a fiber, that previous fiber is interrupted unless onlyIfMissing is set;
in that case the new fiber is interrupted and the existing entry is kept.
Example (Adding a fiber unsafely)
import { Deferred, Effect, Fiber, FiberMap } from "effect"
const program = Effect.gen(function*() {
const map = yield* FiberMap.make<string>()
const deferred = yield* Deferred.make<string>()
// Create a fiber and add it to the map
const fiber = yield* Effect.forkChild(Deferred.await(deferred))
FiberMap.setUnsafe(map, "greeting", fiber)
yield* Deferred.succeed(deferred, "Hello")
// Join the fiber to get its successful value
const result = yield* Fiber.join(fiber)
console.log(result) // "Hello"
})combinators
Source effect/FiberMap.ts:32764 lines
export const const setUnsafe: {
<K, A, E, XE extends E, XA extends A>(
key: K,
fiber: Fiber.Fiber<XA, XE>,
options?:
| {
readonly onlyIfMissing?:
| boolean
| undefined
readonly propagateInterruption?:
| boolean
| undefined
}
| undefined
): (self: FiberMap<K, A, E>) => void
<K, A, E, XE extends E, XA extends A>(
self: FiberMap<K, A, E>,
key: K,
fiber: Fiber.Fiber<XA, XE>,
options?:
| {
readonly onlyIfMissing?:
| boolean
| undefined
readonly propagateInterruption?:
| boolean
| undefined
}
| undefined
): void
}
Adds a fiber to the FiberMap under a key using a synchronous, unsafe
mutation.
When to use
Use when an existing forked fiber must be installed under a key immediately
and synchronous interruption of the replaced fiber is acceptable.
Details
When the fiber completes, it is removed from the map. If the key already has
a fiber, that previous fiber is interrupted unless onlyIfMissing is set;
in that case the new fiber is interrupted and the existing entry is kept.
Example (Adding a fiber unsafely)
import { Deferred, Effect, Fiber, FiberMap } from "effect"
const program = Effect.gen(function*() {
const map = yield* FiberMap.make<string>()
const deferred = yield* Deferred.make<string>()
// Create a fiber and add it to the map
const fiber = yield* Effect.forkChild(Deferred.await(deferred))
FiberMap.setUnsafe(map, "greeting", fiber)
yield* Deferred.succeed(deferred, "Hello")
// Join the fiber to get its successful value
const result = yield* Fiber.join(fiber)
console.log(result) // "Hello"
})
setUnsafe: {
<function (type parameter) K in <K, A, E, XE extends E, XA extends A>(key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): (self: FiberMap<K, A, E>) => void
function (type parameter) A in <K, A, E, XE extends E, XA extends A>(key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): (self: FiberMap<K, A, E>) => void
function (type parameter) E in <K, A, E, XE extends E, XA extends A>(key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): (self: FiberMap<K, A, E>) => void
function (type parameter) XE in <K, A, E, XE extends E, XA extends A>(key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): (self: FiberMap<K, A, E>) => void
function (type parameter) E in <K, A, E, XE extends E, XA extends A>(key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): (self: FiberMap<K, A, E>) => void
function (type parameter) XA in <K, A, E, XE extends E, XA extends A>(key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): (self: FiberMap<K, A, E>) => void
function (type parameter) A in <K, A, E, XE extends E, XA extends A>(key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): (self: FiberMap<K, A, E>) => void
key: Kkey: function (type parameter) K in <K, A, E, XE extends E, XA extends A>(key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): (self: FiberMap<K, A, E>) => void
fiber: Fiber.Fiber<XA, XE>(parameter) fiber: {
id: number;
currentOpCount: number;
getRef: <A>(ref: Context.Reference<A>) => A;
context: Context.Context<never>;
setContext: (context: Context.Context<never>) => void;
currentScheduler: Scheduler;
currentDispatcher: SchedulerDispatcher;
currentSpan: AnySpan | undefined;
currentLogLevel: LogLevel;
minimumLogLevel: LogLevel;
currentStackFrame: StackFrame | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
addObserver: (cb: (exit: Exit<A, E>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit<A, E> | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
import FiberFiber.interface Fiber<out A, out E = never>A runtime fiber is a lightweight thread that executes Effects. Fibers are
the unit of concurrency in Effect. They provide a way to run multiple
Effects concurrently while maintaining structured concurrency and
cancellation safety.
When to use
Use to observe, join, interrupt, or coordinate work that has already been
forked.
Details
A fiber exposes both safe Effect-based operations, such as
await
,
join
, and
interrupt
, and low-level runtime fields used by
the scheduler and runtime internals.
Gotchas
Prefer the exported functions in this module over calling interruptUnsafe
or pollUnsafe directly. The unsafe methods are immediate runtime hooks and
do not provide the same Effect-based sequencing guarantees.
Example (Awaiting a forked fiber)
import { Effect, Fiber } from "effect"
const program = Effect.gen(function*() {
// Fork an effect to run in a new fiber
const fiber = yield* Effect.forkChild(Effect.succeed(42))
// Wait for the fiber to complete and get its result
const result = yield* Fiber.await(fiber)
console.log(result) // Exit.succeed(42)
return result
})
The Fiber namespace contains utility types and functions for working with fibers.
It provides type-level utilities for fiber operations and variance encoding.
When to use
Use to reference type-level helpers associated with Fiber.
Details
The namespace currently exposes type-level support used by the Fiber
interface. Runtime operations are exported as module-level functions.
Example (Working with fiber types)
import { Effect, Fiber } from "effect"
const program = Effect.gen(function*() {
// Create a fiber
const fiber = yield* Effect.forkChild(Effect.succeed(42))
// Use namespace types for variance
const typedFiber: Fiber.Fiber<number, never> = fiber
// Access fiber properties
console.log(`Fiber ID: ${fiber.id}`)
// Join the fiber
const result = yield* Fiber.join(fiber)
return result // 42
})
Fiber<function (type parameter) XA in <K, A, E, XE extends E, XA extends A>(key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): (self: FiberMap<K, A, E>) => void
function (type parameter) XE in <K, A, E, XE extends E, XA extends A>(key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): (self: FiberMap<K, A, E>) => void
options: | {
readonly onlyIfMissing?: boolean | undefined
readonly propagateInterruption?:
| boolean
| undefined
}
| undefined
onlyIfMissing?: boolean | undefinedonlyIfMissing?: boolean | undefined
readonly propagateInterruption?: boolean | undefinedpropagateInterruption?: boolean | undefined
} | undefined
): (self: FiberMap<K, A, E>(parameter) self: {
deferred: Deferred.Deferred<void, unknown>;
state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" };
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
interface FiberMap<in out K, out A = unknown, out E = unknown>A FiberMap is a collection of fibers, indexed by a key. When the associated
Scope is closed, all fibers in the map will be interrupted. Fibers are
automatically removed from the map when they complete.
Example (Managing fibers in a map)
import { Effect, FiberMap } from "effect"
// Create a FiberMap with string keys
const program = Effect.gen(function*() {
const map = yield* FiberMap.make<string>()
// Add some fibers to the map
yield* FiberMap.run(map, "task1", Effect.never)
yield* FiberMap.run(map, "task2", Effect.never)
// Get the size of the map
const size = yield* FiberMap.size(map)
console.log(size) // 2
})
FiberMap<function (type parameter) K in <K, A, E, XE extends E, XA extends A>(key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): (self: FiberMap<K, A, E>) => void
function (type parameter) A in <K, A, E, XE extends E, XA extends A>(key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): (self: FiberMap<K, A, E>) => void
function (type parameter) E in <K, A, E, XE extends E, XA extends A>(key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): (self: FiberMap<K, A, E>) => void
function (type parameter) K in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) A in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) E in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) XE in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) E in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) XA in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) A in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
self: FiberMap<K, A, E>(parameter) self: {
deferred: Deferred.Deferred<void, unknown>;
state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" };
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
interface FiberMap<in out K, out A = unknown, out E = unknown>A FiberMap is a collection of fibers, indexed by a key. When the associated
Scope is closed, all fibers in the map will be interrupted. Fibers are
automatically removed from the map when they complete.
Example (Managing fibers in a map)
import { Effect, FiberMap } from "effect"
// Create a FiberMap with string keys
const program = Effect.gen(function*() {
const map = yield* FiberMap.make<string>()
// Add some fibers to the map
yield* FiberMap.run(map, "task1", Effect.never)
yield* FiberMap.run(map, "task2", Effect.never)
// Get the size of the map
const size = yield* FiberMap.size(map)
console.log(size) // 2
})
FiberMap<function (type parameter) K in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) A in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) E in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
key: Kkey: function (type parameter) K in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
fiber: Fiber.Fiber<XA, XE>(parameter) fiber: {
id: number;
currentOpCount: number;
getRef: <A>(ref: Context.Reference<A>) => A;
context: Context.Context<never>;
setContext: (context: Context.Context<never>) => void;
currentScheduler: Scheduler;
currentDispatcher: SchedulerDispatcher;
currentSpan: AnySpan | undefined;
currentLogLevel: LogLevel;
minimumLogLevel: LogLevel;
currentStackFrame: StackFrame | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
addObserver: (cb: (exit: Exit<A, E>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit<A, E> | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
import FiberFiber.interface Fiber<out A, out E = never>A runtime fiber is a lightweight thread that executes Effects. Fibers are
the unit of concurrency in Effect. They provide a way to run multiple
Effects concurrently while maintaining structured concurrency and
cancellation safety.
When to use
Use to observe, join, interrupt, or coordinate work that has already been
forked.
Details
A fiber exposes both safe Effect-based operations, such as
await
,
join
, and
interrupt
, and low-level runtime fields used by
the scheduler and runtime internals.
Gotchas
Prefer the exported functions in this module over calling interruptUnsafe
or pollUnsafe directly. The unsafe methods are immediate runtime hooks and
do not provide the same Effect-based sequencing guarantees.
Example (Awaiting a forked fiber)
import { Effect, Fiber } from "effect"
const program = Effect.gen(function*() {
// Fork an effect to run in a new fiber
const fiber = yield* Effect.forkChild(Effect.succeed(42))
// Wait for the fiber to complete and get its result
const result = yield* Fiber.await(fiber)
console.log(result) // Exit.succeed(42)
return result
})
The Fiber namespace contains utility types and functions for working with fibers.
It provides type-level utilities for fiber operations and variance encoding.
When to use
Use to reference type-level helpers associated with Fiber.
Details
The namespace currently exposes type-level support used by the Fiber
interface. Runtime operations are exported as module-level functions.
Example (Working with fiber types)
import { Effect, Fiber } from "effect"
const program = Effect.gen(function*() {
// Create a fiber
const fiber = yield* Effect.forkChild(Effect.succeed(42))
// Use namespace types for variance
const typedFiber: Fiber.Fiber<number, never> = fiber
// Access fiber properties
console.log(`Fiber ID: ${fiber.id}`)
// Join the fiber
const result = yield* Fiber.join(fiber)
return result // 42
})
Fiber<function (type parameter) XA in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) XE in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
options: | {
readonly onlyIfMissing?: boolean | undefined
readonly propagateInterruption?:
| boolean
| undefined
}
| undefined
onlyIfMissing?: boolean | undefinedonlyIfMissing?: boolean | undefined
readonly propagateInterruption?: boolean | undefinedpropagateInterruption?: boolean | undefined
} | undefined
): void
} = dual<(...args: Array<any>) => any, <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined) => void>(isDataFirst: (args: IArguments) => boolean, body: <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined) => void): ((...args: Array<any>) => any) & (<K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined) => void) (+1 overload)
Creates a function that can be called in data-first style or data-last
(pipe-friendly) style.
When to use
Use to expose one implementation through both direct and pipe-friendly
call styles.
Details
Pass either the arity of the uncurried function or a predicate that decides
whether the current call is data-first. Arity is the common case. Use a
predicate when optional arguments make arity ambiguous.
Example (Selecting data-first or data-last style by arity)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(2, (self, that) => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Defining overloads with call signatures)
import { Function, pipe } from "effect"
const sum: {
(that: number): (self: number) => number
(self: number, that: number): number
} = Function.dual(2, (self: number, that: number): number => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Selecting data-first or data-last style with a predicate)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(
(args) => args.length === 2,
(self, that) => self + that
)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
dual((args: IArgumentsargs) => const isFiberMap: (
u: unknown
) => u is FiberMap<unknown>
Returns true if a value is a FiberMap.
Details
This is a type guard that checks for the FiberMap runtime marker.
Example (Checking if a value is a FiberMap)
import { Effect, FiberMap } from "effect"
const program = Effect.gen(function*() {
const map = yield* FiberMap.make<string>()
console.log(FiberMap.isFiberMap(map)) // true
console.log(FiberMap.isFiberMap({})) // false
console.log(FiberMap.isFiberMap(null)) // false
})
isFiberMap(args: IArgumentsargs[0]), <function (type parameter) K in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) A in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) E in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) XE in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) E in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) XA in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) A in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
self: FiberMap<K, A, E>(parameter) self: {
deferred: Deferred.Deferred<void, unknown>;
state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" };
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
interface FiberMap<in out K, out A = unknown, out E = unknown>A FiberMap is a collection of fibers, indexed by a key. When the associated
Scope is closed, all fibers in the map will be interrupted. Fibers are
automatically removed from the map when they complete.
Example (Managing fibers in a map)
import { Effect, FiberMap } from "effect"
// Create a FiberMap with string keys
const program = Effect.gen(function*() {
const map = yield* FiberMap.make<string>()
// Add some fibers to the map
yield* FiberMap.run(map, "task1", Effect.never)
yield* FiberMap.run(map, "task2", Effect.never)
// Get the size of the map
const size = yield* FiberMap.size(map)
console.log(size) // 2
})
FiberMap<function (type parameter) K in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) A in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) E in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
key: Kkey: function (type parameter) K in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
fiber: Fiber.Fiber<XA, XE>(parameter) fiber: {
id: number;
currentOpCount: number;
getRef: <A>(ref: Context.Reference<A>) => A;
context: Context.Context<never>;
setContext: (context: Context.Context<never>) => void;
currentScheduler: Scheduler;
currentDispatcher: SchedulerDispatcher;
currentSpan: AnySpan | undefined;
currentLogLevel: LogLevel;
minimumLogLevel: LogLevel;
currentStackFrame: StackFrame | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
addObserver: (cb: (exit: Exit<A, E>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit<A, E> | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
import FiberFiber.interface Fiber<out A, out E = never>A runtime fiber is a lightweight thread that executes Effects. Fibers are
the unit of concurrency in Effect. They provide a way to run multiple
Effects concurrently while maintaining structured concurrency and
cancellation safety.
When to use
Use to observe, join, interrupt, or coordinate work that has already been
forked.
Details
A fiber exposes both safe Effect-based operations, such as
await
,
join
, and
interrupt
, and low-level runtime fields used by
the scheduler and runtime internals.
Gotchas
Prefer the exported functions in this module over calling interruptUnsafe
or pollUnsafe directly. The unsafe methods are immediate runtime hooks and
do not provide the same Effect-based sequencing guarantees.
Example (Awaiting a forked fiber)
import { Effect, Fiber } from "effect"
const program = Effect.gen(function*() {
// Fork an effect to run in a new fiber
const fiber = yield* Effect.forkChild(Effect.succeed(42))
// Wait for the fiber to complete and get its result
const result = yield* Fiber.await(fiber)
console.log(result) // Exit.succeed(42)
return result
})
The Fiber namespace contains utility types and functions for working with fibers.
It provides type-level utilities for fiber operations and variance encoding.
When to use
Use to reference type-level helpers associated with Fiber.
Details
The namespace currently exposes type-level support used by the Fiber
interface. Runtime operations are exported as module-level functions.
Example (Working with fiber types)
import { Effect, Fiber } from "effect"
const program = Effect.gen(function*() {
// Create a fiber
const fiber = yield* Effect.forkChild(Effect.succeed(42))
// Use namespace types for variance
const typedFiber: Fiber.Fiber<number, never> = fiber
// Access fiber properties
console.log(`Fiber ID: ${fiber.id}`)
// Join the fiber
const result = yield* Fiber.join(fiber)
return result // 42
})
Fiber<function (type parameter) XA in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
function (type parameter) XE in <K, A, E, XE extends E, XA extends A>(self: FiberMap<K, A, E>, key: K, fiber: Fiber.Fiber<XA, XE>, options?: {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
} | undefined): void
options: | {
readonly onlyIfMissing?: boolean | undefined
readonly propagateInterruption?:
| boolean
| undefined
}
| undefined
onlyIfMissing?: boolean | undefinedonlyIfMissing?: boolean | undefined
readonly propagateInterruption?: boolean | undefinedpropagateInterruption?: boolean | undefined
} | undefined
): void => {
if (self: FiberMap<K, A, E>(parameter) self: {
deferred: Deferred.Deferred<void, unknown>;
state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" };
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
FiberMap<K, A, E>.state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" }state._tag: "Open" | "Closed"_tag === "Closed") {
fiber: Fiber.Fiber<XA, XE>(parameter) fiber: {
id: number;
currentOpCount: number;
getRef: <A>(ref: Context.Reference<A>) => A;
context: Context.Context<never>;
setContext: (context: Context.Context<never>) => void;
currentScheduler: Scheduler;
currentDispatcher: SchedulerDispatcher;
currentSpan: AnySpan | undefined;
currentLogLevel: LogLevel;
minimumLogLevel: LogLevel;
currentStackFrame: StackFrame | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
addObserver: (cb: (exit: Exit<A, E>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit<A, E> | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
Fiber<XA, XE>.interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => voidinterruptUnsafe(const internalFiberId: -1internalFiberId)
return
}
const const previous: Option.Option<
Fiber.Fiber<A, E>
>
import MutableHashMapMutableHashMap.const get: {
<K>(key: K): <V>(
self: MutableHashMap<K, V>
) => Option.Option<V>
<K, V>(
self: MutableHashMap<K, V>,
key: K
): Option.Option<V>
}
self: FiberMap<K, A, E>(parameter) self: {
deferred: Deferred.Deferred<void, unknown>;
state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" };
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
FiberMap<K, A, E>.state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" }state.backing: MutableHashMap.MutableHashMap<
K,
Fiber.Fiber<A, E>
>
(property) backing: {
backing: Map<K, V>;
buckets: Map<number, NonEmptyArray<K>>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
key: Kkey)
if (const previous: Option.Option<
Fiber.Fiber<A, E>
>
_tag: "None" | "Some"_tag === "Some") {
if (options: | {
readonly onlyIfMissing?: boolean | undefined
readonly propagateInterruption?:
| boolean
| undefined
}
| undefined
onlyIfMissing?: boolean | undefinedonlyIfMissing === true) {
fiber: Fiber.Fiber<XA, XE>(parameter) fiber: {
id: number;
currentOpCount: number;
getRef: <A>(ref: Context.Reference<A>) => A;
context: Context.Context<never>;
setContext: (context: Context.Context<never>) => void;
currentScheduler: Scheduler;
currentDispatcher: SchedulerDispatcher;
currentSpan: AnySpan | undefined;
currentLogLevel: LogLevel;
minimumLogLevel: LogLevel;
currentStackFrame: StackFrame | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
addObserver: (cb: (exit: Exit<A, E>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit<A, E> | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
Fiber<XA, XE>.interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => voidinterruptUnsafe(const internalFiberId: -1internalFiberId)
return
} else if (const previous: Option.Some<
Fiber.Fiber<A, E>
>
const previous: {
_tag: "Some";
_op: "Some";
value: A;
valueOrUndefined: A;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
Some<Fiber<A, E>>.value: Fiber.Fiber<A, E>(property) Some<Fiber<A, E>>.value: {
id: number;
currentOpCount: number;
getRef: <A>(ref: Context.Reference<A>) => A;
context: Context.Context<never>;
setContext: (context: Context.Context<never>) => void;
currentScheduler: Scheduler;
currentDispatcher: SchedulerDispatcher;
currentSpan: AnySpan | undefined;
currentLogLevel: LogLevel;
minimumLogLevel: LogLevel;
currentStackFrame: StackFrame | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
addObserver: (cb: (exit: Exit<A, E>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit<A, E> | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
fiber: Fiber.Fiber<XA, XE>(parameter) fiber: {
id: number;
currentOpCount: number;
getRef: <A>(ref: Context.Reference<A>) => A;
context: Context.Context<never>;
setContext: (context: Context.Context<never>) => void;
currentScheduler: Scheduler;
currentDispatcher: SchedulerDispatcher;
currentSpan: AnySpan | undefined;
currentLogLevel: LogLevel;
minimumLogLevel: LogLevel;
currentStackFrame: StackFrame | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
addObserver: (cb: (exit: Exit<A, E>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit<A, E> | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
const previous: Option.Some<
Fiber.Fiber<A, E>
>
const previous: {
_tag: "Some";
_op: "Some";
value: A;
valueOrUndefined: A;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
Some<Fiber<A, E>>.value: Fiber.Fiber<A, E>(property) Some<Fiber<A, E>>.value: {
id: number;
currentOpCount: number;
getRef: <A>(ref: Context.Reference<A>) => A;
context: Context.Context<never>;
setContext: (context: Context.Context<never>) => void;
currentScheduler: Scheduler;
currentDispatcher: SchedulerDispatcher;
currentSpan: AnySpan | undefined;
currentLogLevel: LogLevel;
minimumLogLevel: LogLevel;
currentStackFrame: StackFrame | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
addObserver: (cb: (exit: Exit<A, E>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit<A, E> | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
Fiber<A, E>.interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => voidinterruptUnsafe(const internalFiberId: -1internalFiberId)
}
import MutableHashMapMutableHashMap.const set: {
<K, V>(key: K, value: V): (
self: MutableHashMap<K, V>
) => MutableHashMap<K, V>
<K, V>(
self: MutableHashMap<K, V>,
key: K,
value: V
): MutableHashMap<K, V>
}
self: FiberMap<K, A, E>(parameter) self: {
deferred: Deferred.Deferred<void, unknown>;
state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" };
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
FiberMap<K, A, E>.state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" }state.backing: MutableHashMap.MutableHashMap<
K,
Fiber.Fiber<A, E>
>
(property) backing: {
backing: Map<K, V>;
buckets: Map<number, NonEmptyArray<K>>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
key: Kkey, fiber: Fiber.Fiber<XA, XE>(parameter) fiber: {
id: number;
currentOpCount: number;
getRef: <A>(ref: Context.Reference<A>) => A;
context: Context.Context<never>;
setContext: (context: Context.Context<never>) => void;
currentScheduler: Scheduler;
currentDispatcher: SchedulerDispatcher;
currentSpan: AnySpan | undefined;
currentLogLevel: LogLevel;
minimumLogLevel: LogLevel;
currentStackFrame: StackFrame | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
addObserver: (cb: (exit: Exit<A, E>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit<A, E> | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
fiber: Fiber.Fiber<XA, XE>(parameter) fiber: {
id: number;
currentOpCount: number;
getRef: <A>(ref: Context.Reference<A>) => A;
context: Context.Context<never>;
setContext: (context: Context.Context<never>) => void;
currentScheduler: Scheduler;
currentDispatcher: SchedulerDispatcher;
currentSpan: AnySpan | undefined;
currentLogLevel: LogLevel;
minimumLogLevel: LogLevel;
currentStackFrame: StackFrame | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
addObserver: (cb: (exit: Exit<A, E>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit<A, E> | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
Fiber<XA, XE>.addObserver: (cb: (exit: Exit<A, E>) => void) => () => voidaddObserver((exit: Exit.Exit<XA, XE>exit) => {
if (self: FiberMap<K, A, E>(parameter) self: {
deferred: Deferred.Deferred<void, unknown>;
state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" };
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
FiberMap<K, A, E>.state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" }state._tag: "Open" | "Closed"_tag === "Closed") {
return
}
const const current: Option.Option<
Fiber.Fiber<A, E>
>
import MutableHashMapMutableHashMap.const get: {
<K>(key: K): <V>(
self: MutableHashMap<K, V>
) => Option.Option<V>
<K, V>(
self: MutableHashMap<K, V>,
key: K
): Option.Option<V>
}
self: FiberMap<K, A, E>(parameter) self: {
deferred: Deferred.Deferred<void, unknown>;
state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" };
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
FiberMap<K, A, E>.state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" }state.backing: MutableHashMap.MutableHashMap<
K,
Fiber.Fiber<A, E>
>
(property) backing: {
backing: Map<K, V>;
buckets: Map<number, NonEmptyArray<K>>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
key: Kkey)
if (import OptionOption.const isSome: <A>(
self: Option<A>
) => self is Some<A>
Checks whether an Option contains a value (Some).
When to use
Use when you need to branch on a present Option before accessing .value.
Details
- Acts as a type guard, narrowing to
Some<A>
Example (Checking for Some)
import { Option } from "effect"
console.log(Option.isSome(Option.some(1)))
// Output: true
console.log(Option.isSome(Option.none()))
// Output: false
isSome(const current: Option.Option<
Fiber.Fiber<A, E>
>
fiber: Fiber.Fiber<XA, XE>(parameter) fiber: {
id: number;
currentOpCount: number;
getRef: <A>(ref: Context.Reference<A>) => A;
context: Context.Context<never>;
setContext: (context: Context.Context<never>) => void;
currentScheduler: Scheduler;
currentDispatcher: SchedulerDispatcher;
currentSpan: AnySpan | undefined;
currentLogLevel: LogLevel;
minimumLogLevel: LogLevel;
currentStackFrame: StackFrame | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
addObserver: (cb: (exit: Exit<A, E>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit<A, E> | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
const current: Option.Some<
Fiber.Fiber<A, E>
>
const current: {
_tag: "Some";
_op: "Some";
value: A;
valueOrUndefined: A;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
Some<Fiber<A, E>>.value: Fiber.Fiber<A, E>(property) Some<Fiber<A, E>>.value: {
id: number;
currentOpCount: number;
getRef: <A>(ref: Context.Reference<A>) => A;
context: Context.Context<never>;
setContext: (context: Context.Context<never>) => void;
currentScheduler: Scheduler;
currentDispatcher: SchedulerDispatcher;
currentSpan: AnySpan | undefined;
currentLogLevel: LogLevel;
minimumLogLevel: LogLevel;
currentStackFrame: StackFrame | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
addObserver: (cb: (exit: Exit<A, E>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit<A, E> | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
import MutableHashMapMutableHashMap.const remove: {
<K>(key: K): <V>(
self: MutableHashMap<K, V>
) => MutableHashMap<K, V>
<K, V>(
self: MutableHashMap<K, V>,
key: K
): MutableHashMap<K, V>
}
self: FiberMap<K, A, E>(parameter) self: {
deferred: Deferred.Deferred<void, unknown>;
state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" };
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
FiberMap<K, A, E>.state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" }state.backing: MutableHashMap.MutableHashMap<
K,
Fiber.Fiber<A, E>
>
(property) backing: {
backing: Map<K, V>;
buckets: Map<number, NonEmptyArray<K>>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
key: Kkey)
}
if (
import ExitExit.const isFailure: <A, E>(
self: Exit<A, E>
) => self is Failure<A, E>
Checks whether an Exit is a Failure.
When to use
Use as a type guard to narrow Exit<A, E> to Failure<A, E> and access the
cause property.
Example (Narrowing to failure)
import { Exit } from "effect"
const exit = Exit.fail("error")
if (Exit.isFailure(exit)) {
console.log(exit.cause)
}
isFailure(exit: Exit.Exit<XA, XE>exit) &&
(
options: | {
readonly onlyIfMissing?: boolean | undefined
readonly propagateInterruption?:
| boolean
| undefined
}
| undefined
propagateInterruption?: boolean | undefinedpropagateInterruption === true ?
!const isInternalInterruption: <XE>(
a: Cause.Cause<XE>
) => boolean
exit: Exit.Failure<XA, XE>(parameter) exit: {
_tag: "Failure";
cause: Cause.Cause<E>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
Failure<XA, XE>.cause: Cause.Cause<E>(property) Failure<XA, XE>.cause: {
reasons: ReadonlyArray<Reason<E>>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
import CauseCause.const hasInterruptsOnly: <E>(
self: Cause<E>
) => boolean
Returns true if every reason in the cause is an Interrupt (and
there is at least one reason).
When to use
Use when you need to detect failures caused only by interruption.
Example (Checking interrupt-only causes)
import { Cause } from "effect"
console.log(Cause.hasInterruptsOnly(Cause.interrupt(123))) // true
console.log(Cause.hasInterruptsOnly(Cause.fail("error"))) // false
console.log(Cause.hasInterruptsOnly(Cause.empty)) // false
hasInterruptsOnly(exit: Exit.Failure<XA, XE>(parameter) exit: {
_tag: "Failure";
cause: Cause.Cause<E>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
Failure<XA, XE>.cause: Cause.Cause<E>(property) Failure<XA, XE>.cause: {
reasons: ReadonlyArray<Reason<E>>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
import DeferredDeferred.const doneUnsafe: <A, E>(
self: Deferred<A, E>,
effect: Effect<A, E>
) => boolean
Attempts to complete the Deferred synchronously with the specified
completion effect.
When to use
Use to complete a Deferred synchronously in low-level code that already has
the completion effect.
Details
This mutates the Deferred directly and should be reserved for low-level
code; prefer the effectful completion APIs when possible. Returns true if
this call completed the Deferred, or false if it was already completed.
Example (Completing a Deferred unsafely)
import { Deferred, Effect } from "effect"
const deferred = Deferred.makeUnsafe<number>()
const success = Deferred.doneUnsafe(deferred, Effect.succeed(42))
console.log(success) // true
doneUnsafe(self: FiberMap<K, A, E>(parameter) self: {
deferred: Deferred.Deferred<void, unknown>;
state: { readonly _tag: "Open"; readonly backing: MutableHashMap.MutableHashMap<K, Fiber.Fiber<A, E>> } | { readonly _tag: "Closed" };
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
FiberMap<in out K, out A = unknown, out E = unknown>.deferred: Deferred.Deferred<void, unknown>(property) FiberMap<in out K, out A = unknown, out E = unknown>.deferred: {
effect: Effect<A, E>;
resumes: Array<(effect: Effect<A, E>) => void> | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
exit: Exit.Failure<XA, XE>(parameter) exit: {
_tag: "Failure";
cause: Cause.Cause<E>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
Referenced by 2 symbols