<K, A, E>(self: FiberMap<K, A, E>): <R = never>() => Effect.Effect<
<XE extends E, XA extends A>(
key: K,
effect: Effect.Effect<XA, XE, R>,
options?:
| (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined
readonly propagateInterruption?: boolean | undefined
})
| undefined
) => Fiber.Fiber<XA, XE>,
never,
R
>Captures the current runtime and returns a function for forking effects into
an existing FiberMap.
Details
Each call stores the forked fiber under the supplied key. If that key already
has a fiber, the previous fiber is interrupted unless onlyIfMissing is set.
Example (Capturing a runtime)
import { Context, Effect, FiberMap } from "effect"
interface Users {
readonly _: unique symbol
}
const Users = Context.Service<Users, {
getAll: Effect.Effect<Array<unknown>>
}>("Users")
Effect.gen(function*() {
const map = yield* FiberMap.make<string>()
const run = yield* FiberMap.runtime(map)<Users>()
// run some effects and add the fibers to the map
run("effect-a", Effect.andThen(Users, (_) => _.getAll))
run("effect-b", Effect.andThen(Users, (_) => _.getAll))
}).pipe(
Effect.scoped // The fibers will be interrupted when the scope is closed
)combinators
Source effect/FiberMap.ts:82641 lines
export const const runtime: <K, A, E>(
self: FiberMap<K, A, E>
) => <R = never>() => Effect.Effect<
<XE extends E, XA extends A>(
key: K,
effect: Effect.Effect<XA, XE, R>,
options?:
| (Effect.RunOptions & {
readonly onlyIfMissing?:
| boolean
| undefined
readonly propagateInterruption?:
| boolean
| undefined
})
| undefined
) => Fiber.Fiber<XA, XE>,
never,
R
>
Captures the current runtime and returns a function for forking effects into
an existing FiberMap.
Details
Each call stores the forked fiber under the supplied key. If that key already
has a fiber, the previous fiber is interrupted unless onlyIfMissing is set.
Example (Capturing a runtime)
import { Context, Effect, FiberMap } from "effect"
interface Users {
readonly _: unique symbol
}
const Users = Context.Service<Users, {
getAll: Effect.Effect<Array<unknown>>
}>("Users")
Effect.gen(function*() {
const map = yield* FiberMap.make<string>()
const run = yield* FiberMap.runtime(map)<Users>()
// run some effects and add the fibers to the map
run("effect-a", Effect.andThen(Users, (_) => _.getAll))
run("effect-b", Effect.andThen(Users, (_) => _.getAll))
}).pipe(
Effect.scoped // The fibers will be interrupted when the scope is closed
)
runtime: <function (type parameter) K in <K, A, E>(self: FiberMap<K, A, E>): <R = never>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<XA, XE>), never, R>
function (type parameter) A in <K, A, E>(self: FiberMap<K, A, E>): <R = never>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<XA, XE>), never, R>
function (type parameter) E in <K, A, E>(self: FiberMap<K, A, E>): <R = never>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<XA, XE>), never, R>
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>(self: FiberMap<K, A, E>): <R = never>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<XA, XE>), never, R>
function (type parameter) A in <K, A, E>(self: FiberMap<K, A, E>): <R = never>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<XA, XE>), never, R>
function (type parameter) E in <K, A, E>(self: FiberMap<K, A, E>): <R = never>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<XA, XE>), never, R>
function (type parameter) R in <R = never>(): Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<XA, XE>), never, R>
import EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<
<function (type parameter) XE in <XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined): Fiber.Fiber<XA, XE>
function (type parameter) E in <K, A, E>(self: FiberMap<K, A, E>): <R = never>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<XA, XE>), never, R>
function (type parameter) XA in <XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined): Fiber.Fiber<XA, XE>
function (type parameter) A in <K, A, E>(self: FiberMap<K, A, E>): <R = never>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<XA, XE>), never, R>
key: Kkey: function (type parameter) K in <K, A, E>(self: FiberMap<K, A, E>): <R = never>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<XA, XE>), never, R>
effect: Effect.Effect<XA, XE, R>(parameter) effect: {
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 EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<function (type parameter) XA in <XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined): Fiber.Fiber<XA, XE>
function (type parameter) XE in <XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined): Fiber.Fiber<XA, XE>
function (type parameter) R in <R = never>(): Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<XA, XE>), never, R>
options: | (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined
readonly propagateInterruption?:
| boolean
| undefined
})
| undefined
import EffectEffect.RunOptions & {
readonly onlyIfMissing?: boolean | undefinedonlyIfMissing?: boolean | undefined
readonly propagateInterruption?: boolean | undefinedpropagateInterruption?: boolean | undefined
}
| undefined
) => 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 <XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined): Fiber.Fiber<XA, XE>
function (type parameter) XE in <XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined): Fiber.Fiber<XA, XE>
function (type parameter) R in <R = never>(): Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<XA, XE>), never, R>
function (type parameter) K in <K, A, E>(self: FiberMap<K, A, E>): <R>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<...>), never, R>
function (type parameter) A in <K, A, E>(self: FiberMap<K, A, E>): <R>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<...>), never, R>
function (type parameter) E in <K, A, E>(self: FiberMap<K, A, E>): <R>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<...>), never, R>
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>(self: FiberMap<K, A, E>): <R>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<...>), never, R>
function (type parameter) A in <K, A, E>(self: FiberMap<K, A, E>): <R>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<...>), never, R>
function (type parameter) E in <K, A, E>(self: FiberMap<K, A, E>): <R>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<...>), never, R>
function (type parameter) R in <R>(): Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<...>), never, R>
import EffectEffect.const map: {
<A, B>(f: (a: A) => B): <E, R>(
self: Effect<A, E, R>
) => Effect<B, E, R>
<A, E, R, B>(
self: Effect<A, E, R>,
f: (a: A) => B
): Effect<B, E, R>
}
import EffectEffect.const context: <R = never>() => Effect<
Context.Context<R>,
never,
R
>
Returns the complete context.
When to use
Use to read the complete Context available to the current effect.
Details
This function allows you to access all services that are currently available
in the effect's environment. This can be useful for debugging, introspection,
or when you need to pass the entire context to another function.
Example (Reading the full context)
import { Console, Context, Effect, Option } from "effect"
const Logger = Context.Service<{
log: (msg: string) => void
}>("Logger")
const Database = Context.Service<{
query: (sql: string) => string
}>("Database")
const program = Effect.gen(function*() {
const allServices = yield* Effect.context()
// Check if specific services are available
const loggerOption = Context.getOption(allServices, Logger)
const databaseOption = Context.getOption(allServices, Database)
yield* Console.log(`Logger available: ${Option.isSome(loggerOption)}`)
yield* Console.log(`Database available: ${Option.isSome(databaseOption)}`)
})
const context = Context.make(Logger, { log: console.log })
.pipe(Context.add(Database, { query: () => "result" }))
const provided = Effect.provideContext(program, context)
context<function (type parameter) R in <R>(): Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<...>), never, R>
services: Context<R>(parameter) services: {
mapUnsafe: ReadonlyMap<string, any>;
mutable: boolean;
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;
}
const runFork: (
effect: Effect<A, E, R>,
options?: RunOptions | undefined
) => Fiber<A, E>
import EffectEffect.const runForkWith: <R>(
context: Context.Context<R>
) => <A, E>(
effect: Effect<A, E, R>,
options?: RunOptions | undefined
) => Fiber<A, E>
Runs an effect in the background with the provided services.
When to use
Use when an effect still requires services, you already have a Context, and
you want a background fiber.
Example (Running with services in the background)
import { Context, Effect } from "effect"
interface Logger {
log: (message: string) => void
}
const Logger = Context.Service<Logger>("Logger")
const services = Context.make(Logger, {
log: (message) => console.log(message)
})
const program = Effect.gen(function*() {
const logger = yield* Logger
logger.log("Hello from service!")
return "done"
})
const fiber = Effect.runForkWith(services)(program)
runForkWith(services: Context<R>(parameter) services: {
mapUnsafe: ReadonlyMap<string, any>;
mutable: boolean;
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;
}
function (type parameter) XE in <XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined): Fiber.Fiber<...>
function (type parameter) E in <K, A, E>(self: FiberMap<K, A, E>): <R>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<...>), never, R>
function (type parameter) XA in <XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined): Fiber.Fiber<...>
function (type parameter) A in <K, A, E>(self: FiberMap<K, A, E>): <R>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<...>), never, R>
key: Kkey: function (type parameter) K in <K, A, E>(self: FiberMap<K, A, E>): <R>() => Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<...>), never, R>
effect: Effect.Effect<XA, XE, R>(parameter) effect: {
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 EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<function (type parameter) XA in <XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined): Fiber.Fiber<...>
function (type parameter) XE in <XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined): Fiber.Fiber<...>
function (type parameter) R in <R>(): Effect.Effect<(<XE extends E, XA extends A>(key: K, effect: Effect.Effect<XA, XE, R>, options?: (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined;
readonly propagateInterruption?: boolean | undefined;
}) | undefined) => Fiber.Fiber<...>), never, R>
options: | (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined
readonly propagateInterruption?:
| boolean
| undefined
})
| undefined
import EffectEffect.RunOptions & {
readonly onlyIfMissing?: boolean | undefinedonlyIfMissing?: boolean | undefined
readonly propagateInterruption?: boolean | undefinedpropagateInterruption?: boolean | undefined
}
| undefined
) => {
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 constInterruptedFiber: () => Fiber.Fiber<
never,
never
>
options: | (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined
readonly propagateInterruption?:
| boolean
| undefined
})
| undefined
onlyIfMissing?: boolean | undefinedonlyIfMissing === true && const hasUnsafe: {
<K>(key: K): <A, E>(
self: FiberMap<K, A, E>
) => boolean
<K, A, E>(
self: FiberMap<K, A, E>,
key: K
): boolean
}
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;
}
key: Kkey)) {
return const constInterruptedFiber: () => Fiber.Fiber<
never,
never
>
const fiber: Fiber.Fiber<XA, XE>const 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 runFork: (
effect: Effect<A, E, R>,
options?: RunOptions | undefined
) => Fiber<A, E>
effect: Effect.Effect<XA, XE, R>(parameter) effect: {
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;
}
options: | (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined
readonly propagateInterruption?:
| boolean
| undefined
})
| undefined
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
}
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;
}
key: Kkey, const fiber: Fiber.Fiber<XA, XE>const 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; <…;
}
options: | (Effect.RunOptions & {
readonly onlyIfMissing?: boolean | undefined
readonly propagateInterruption?:
| boolean
| undefined
})
| undefined
const fiber: Fiber.Fiber<XA, XE>const 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; <…;
}
Referenced by 2 symbols