<K>(key: K): <A, E>(
self: RcMap<K, A, E>
) => Effect.Effect<A, E, Scope.Scope>
<K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>Gets the resource for a key, acquiring it with the map's lookup function when the key is not already cached.
When to use
Use to acquire or retain the resource for a key within the current scope.
Details
The resource's reference count is incremented for the current Scope, and a
release finalizer is added to that scope. When the current scope closes, the
reference is released; the resource is closed when the last reference is
released, subject to the map's idle time-to-live setting.
Example (Acquiring a resource)
import { Effect, RcMap } from "effect"
Effect.gen(function*() {
const map = yield* RcMap.make({
lookup: (key: string) =>
Effect.acquireRelease(
Effect.succeed(`Resource: ${key}`),
() => Effect.log(`Released ${key}`)
)
})
// Get a resource - it will be acquired on first access
const resource = yield* RcMap.get(map, "database")
console.log(resource) // "Resource: database"
}).pipe(Effect.scoped)export const const get: {
<K>(key: K): <A, E>(
self: RcMap<K, A, E>
) => Effect.Effect<A, E, Scope.Scope>
<K, A, E>(
self: RcMap<K, A, E>,
key: K
): Effect.Effect<A, E, Scope.Scope>
}
Gets the resource for a key, acquiring it with the map's lookup function when
the key is not already cached.
When to use
Use to acquire or retain the resource for a key within the current scope.
Details
The resource's reference count is incremented for the current Scope, and a
release finalizer is added to that scope. When the current scope closes, the
reference is released; the resource is closed when the last reference is
released, subject to the map's idle time-to-live setting.
Example (Acquiring a resource)
import { Effect, RcMap } from "effect"
Effect.gen(function*() {
const map = yield* RcMap.make({
lookup: (key: string) =>
Effect.acquireRelease(
Effect.succeed(`Resource: ${key}`),
() => Effect.log(`Released ${key}`)
)
})
// Get a resource - it will be acquired on first access
const resource = yield* RcMap.get(map, "database")
console.log(resource) // "Resource: database"
}).pipe(Effect.scoped)
get: {
<function (type parameter) K in <K>(key: K): <A, E>(self: RcMap<K, A, E>) => Effect.Effect<A, E, Scope.Scope>K>(key: Kkey: function (type parameter) K in <K>(key: K): <A, E>(self: RcMap<K, A, E>) => Effect.Effect<A, E, Scope.Scope>K): <function (type parameter) A in <A, E>(self: RcMap<K, A, E>): Effect.Effect<A, E, Scope.Scope>A, function (type parameter) E in <A, E>(self: RcMap<K, A, E>): Effect.Effect<A, E, Scope.Scope>E>(self: RcMap<K, A, E>(parameter) self: {
lookup: (key: K) => Effect.Effect<A, E, Scope.Scope>;
context: Context.Context<never>;
scope: Scope.Scope;
idleTimeToLive: (key: K) => Duration.Duration;
capacity: number;
state: State<K, A, 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; <…;
}
interface RcMap<in out K, in out A, in out E = never>An RcMap is a reference-counted map data structure that manages the lifecycle
of resources indexed by keys. Resources are lazily acquired and automatically
released when no longer in use.
When to use
Use to share scoped resources by key while automatically releasing them after
their last active reference is gone.
Example (Inspecting a reference-counted map)
import { Effect, RcMap } from "effect"
Effect.gen(function*() {
// Create an RcMap that manages database connections
const dbConnectionMap = yield* RcMap.make({
lookup: (dbName: string) =>
Effect.acquireRelease(
Effect.succeed(`Connection to ${dbName}`),
(conn) => Effect.log(`Closing ${conn}`)
),
capacity: 10,
idleTimeToLive: "5 minutes"
})
// The RcMap interface provides access to:
// - lookup: Function to acquire resources
// - capacity: Maximum number of resources
// - idleTimeToLive: Time before idle resources are released
// - state: Current state of the map
console.log(`Capacity: ${dbConnectionMap.capacity}`)
}).pipe(Effect.scoped)
RcMap<function (type parameter) K in <K>(key: K): <A, E>(self: RcMap<K, A, E>) => Effect.Effect<A, E, Scope.Scope>K, function (type parameter) A in <A, E>(self: RcMap<K, A, E>): Effect.Effect<A, E, Scope.Scope>A, function (type parameter) E in <A, E>(self: RcMap<K, A, E>): Effect.Effect<A, E, Scope.Scope>E>) => 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) A in <A, E>(self: RcMap<K, A, E>): Effect.Effect<A, E, Scope.Scope>A, function (type parameter) E in <A, E>(self: RcMap<K, A, E>): Effect.Effect<A, E, Scope.Scope>E, import ScopeScope.Scope>
<function (type parameter) K in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>K, function (type parameter) A in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>A, function (type parameter) E in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>E>(self: RcMap<K, A, E>(parameter) self: {
lookup: (key: K) => Effect.Effect<A, E, Scope.Scope>;
context: Context.Context<never>;
scope: Scope.Scope;
idleTimeToLive: (key: K) => Duration.Duration;
capacity: number;
state: State<K, A, 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; <…;
}
interface RcMap<in out K, in out A, in out E = never>An RcMap is a reference-counted map data structure that manages the lifecycle
of resources indexed by keys. Resources are lazily acquired and automatically
released when no longer in use.
When to use
Use to share scoped resources by key while automatically releasing them after
their last active reference is gone.
Example (Inspecting a reference-counted map)
import { Effect, RcMap } from "effect"
Effect.gen(function*() {
// Create an RcMap that manages database connections
const dbConnectionMap = yield* RcMap.make({
lookup: (dbName: string) =>
Effect.acquireRelease(
Effect.succeed(`Connection to ${dbName}`),
(conn) => Effect.log(`Closing ${conn}`)
),
capacity: 10,
idleTimeToLive: "5 minutes"
})
// The RcMap interface provides access to:
// - lookup: Function to acquire resources
// - capacity: Maximum number of resources
// - idleTimeToLive: Time before idle resources are released
// - state: Current state of the map
console.log(`Capacity: ${dbConnectionMap.capacity}`)
}).pipe(Effect.scoped)
RcMap<function (type parameter) K in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>K, function (type parameter) A in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>A, function (type parameter) E in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>E>, key: Kkey: function (type parameter) K in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>K): 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) A in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>A, function (type parameter) E in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>E, import ScopeScope.Scope>
} = dual<(...args: Array<any>) => any, <K, A, E>(self: RcMap<K, A, E>, key: K) => Effect.Effect<A, E, Scope.Scope>>(arity: 2, body: <K, A, E>(self: RcMap<K, A, E>, key: K) => Effect.Effect<A, E, Scope.Scope>): ((...args: Array<any>) => any) & (<K, A, E>(self: RcMap<K, A, E>, key: K) => Effect.Effect<A, E, Scope.Scope>) (+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(
2,
<function (type parameter) K in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>K, function (type parameter) A in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>A, function (type parameter) E in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>E>(self: RcMap<K, A, E>(parameter) self: {
lookup: (key: K) => Effect.Effect<A, E, Scope.Scope>;
context: Context.Context<never>;
scope: Scope.Scope;
idleTimeToLive: (key: K) => Duration.Duration;
capacity: number;
state: State<K, A, 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; <…;
}
interface RcMap<in out K, in out A, in out E = never>An RcMap is a reference-counted map data structure that manages the lifecycle
of resources indexed by keys. Resources are lazily acquired and automatically
released when no longer in use.
When to use
Use to share scoped resources by key while automatically releasing them after
their last active reference is gone.
Example (Inspecting a reference-counted map)
import { Effect, RcMap } from "effect"
Effect.gen(function*() {
// Create an RcMap that manages database connections
const dbConnectionMap = yield* RcMap.make({
lookup: (dbName: string) =>
Effect.acquireRelease(
Effect.succeed(`Connection to ${dbName}`),
(conn) => Effect.log(`Closing ${conn}`)
),
capacity: 10,
idleTimeToLive: "5 minutes"
})
// The RcMap interface provides access to:
// - lookup: Function to acquire resources
// - capacity: Maximum number of resources
// - idleTimeToLive: Time before idle resources are released
// - state: Current state of the map
console.log(`Capacity: ${dbConnectionMap.capacity}`)
}).pipe(Effect.scoped)
RcMap<function (type parameter) K in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>K, function (type parameter) A in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>A, function (type parameter) E in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>E>, key: Kkey: function (type parameter) K in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>K): 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) A in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>A, function (type parameter) E in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>E, import ScopeScope.Scope> =>
import EffectEffect.const uninterruptibleMask: <A, E, R>(
f: (
restore: <AX, EX, RX>(
effect: Effect<AX, EX, RX>
) => Effect<AX, EX, RX>
) => Effect<A, E, R>
) => Effect<A, E, R>
Disables interruption and provides a restore function to restore the
interruptible state within the effect.
Example (Restoring interruption in protected regions)
import { Console, Effect } from "effect"
const program = Effect.uninterruptibleMask((restore) =>
Effect.gen(function*() {
yield* Console.log("Uninterruptible phase...")
yield* Effect.sleep("1 second")
// Restore interruptibility for this part
yield* restore(
Effect.gen(function*() {
yield* Console.log("Interruptible phase...")
yield* Effect.sleep("2 seconds")
})
)
yield* Console.log("Back to uninterruptible")
})
)
uninterruptibleMask((restore: <AX, EX, RX>(
effect: Effect<AX, EX, RX>
) => Effect<AX, EX, RX>
self: RcMap<K, A, E>(parameter) self: {
lookup: (key: K) => Effect.Effect<A, E, Scope.Scope>;
context: Context.Context<never>;
scope: Scope.Scope;
idleTimeToLive: (key: K) => Duration.Duration;
capacity: number;
state: State<K, A, 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; <…;
}
RcMap<K, A, E>.state: State<K, A, E>state._tag: "Open" | "Closed"_tag === "Closed") {
return import EffectEffect.const interrupt: Effect<never>const interrupt: {
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;
}
Returns an effect that is immediately interrupted.
Example (Creating an interrupted effect)
import { Effect } from "effect"
const program = Effect.gen(function*() {
return yield* Effect.interrupt
yield* Effect.succeed("This won't execute and is unreachable")
})
Effect.runPromise(program).catch(console.error)
// Throws: InterruptedException
interrupt
}
const const state: State.Open<K, A, E>const state: {
_tag: "Open";
map: MutableHashMap.MutableHashMap<K, Entry<A, E>>;
}
self: RcMap<K, A, E>(parameter) self: {
lookup: (key: K) => Effect.Effect<A, E, Scope.Scope>;
context: Context.Context<never>;
scope: Scope.Scope;
idleTimeToLive: (key: K) => Duration.Duration;
capacity: number;
state: State<K, A, 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; <…;
}
RcMap<K, A, E>.state: State<K, A, E>(property) RcMap<K, A, E>.state: {
_tag: "Open";
map: MutableHashMap.MutableHashMap<K, Entry<A, E>>;
}
const parent: Fiber.Fiber<any, any>const parent: {
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.const getCurrent: () =>
| Fiber<any, any>
| undefined
Returns the current fiber if called from within a fiber context,
otherwise returns undefined.
When to use
Use when you need low-level runtime integrations that need access to the currently
executing fiber.
Gotchas
This is a synchronous accessor, not an Effect. It returns undefined outside
an active fiber runtime context.
Example (Getting the current fiber)
import { Effect, Fiber } from "effect"
const program = Effect.gen(function*() {
const current = Fiber.getCurrent()
if (current) {
console.log(`Current fiber ID: ${current.id}`)
}
})
getCurrent()!
const const o: Option<State.Entry<A, E>>o = 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>
}
const state: State.Open<K, A, E>const state: {
_tag: "Open";
map: MutableHashMap.MutableHashMap<K, Entry<A, E>>;
}
State<K, A, E>.Open<K, A, E>.map: MutableHashMap.MutableHashMap<K, Entry<A, E>>(property) State<K, A, E>.Open<K, A, E>.map: {
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)
let let entry: State.Entry<A, E>let entry: {
deferred: Deferred.Deferred<A, E>;
scope: Scope.Closeable;
finalizer: Effect.Effect<void>;
idleTimeToLive: Duration.Duration;
fiber: Fiber.Fiber<void> | undefined;
expiresAt: number;
refCount: number;
}
interface State<K, A, E>.Entry<A, E>Represents an individual entry in the RcMap, containing the resource's
metadata including reference count, expiration time, and lifecycle management.
When to use
Use when inspecting the stored resource, reference count, and idle lifecycle
metadata for a single key.
Entry<function (type parameter) A in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>A, function (type parameter) E in <K, A, E>(self: RcMap<K, A, E>, key: K): Effect.Effect<A, E, Scope.Scope>E>
if (const o: Option<State.Entry<A, E>>o._tag: "None" | "Some"_tag === "Some") {
let entry: State.Entry<A, E>let entry: {
deferred: Deferred.Deferred<A, E>;
scope: Scope.Closeable;
finalizer: Effect.Effect<void>;
idleTimeToLive: Duration.Duration;
fiber: Fiber.Fiber<void> | undefined;
expiresAt: number;
refCount: number;
}
const o: Some<State.Entry<A, E>>const o: {
_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<State<K, A, E>.Entry<A, E>>.value: State.Entry<A, E>(property) Some<State<K, A, E>.Entry<A, E>>.value: {
deferred: Deferred.Deferred<A, E>;
scope: Scope.Closeable;
finalizer: Effect.Effect<void>;
idleTimeToLive: Duration.Duration;
fiber: Fiber.Fiber<void> | undefined;
expiresAt: number;
refCount: number;
}
let entry: State.Entry<A, E>let entry: {
deferred: Deferred.Deferred<A, E>;
scope: Scope.Closeable;
finalizer: Effect.Effect<void>;
idleTimeToLive: Duration.Duration;
fiber: Fiber.Fiber<void> | undefined;
expiresAt: number;
refCount: number;
}
State<K, A, E>.Entry<A, E>.refCount: numberrefCount++
} else if (var Number: NumberConstructorAn object that represents a number of any kind. All JavaScript numbers are 64-bit floating-point numbers.
Number.NumberConstructor.isFinite(number: unknown): booleanReturns true if passed value is finite.
Unlike the global isFinite, Number.isFinite doesn't forcibly convert the parameter to a
number. Only finite values of the type number, result in true.
isFinite(self: RcMap<K, A, E>(parameter) self: {
lookup: (key: K) => Effect.Effect<A, E, Scope.Scope>;
context: Context.Context<never>;
scope: Scope.Scope;
idleTimeToLive: (key: K) => Duration.Duration;
capacity: number;
state: State<K, A, 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; <…;
}
RcMap<in out K, in out A, in out E = never>.capacity: numbercapacity) && import MutableHashMapMutableHashMap.const size: <K, V>(
self: MutableHashMap<K, V>
) => number
Returns the number of key-value pairs in the MutableHashMap.
When to use
Use to read how many entries are currently stored in the mutable hash map.
Example (Checking map size)
import { MutableHashMap } from "effect"
const map = MutableHashMap.empty<string, number>()
console.log(MutableHashMap.size(map)) // 0
MutableHashMap.set(map, "key1", 42)
MutableHashMap.set(map, "key2", 100)
console.log(MutableHashMap.size(map)) // 2
MutableHashMap.remove(map, "key1")
console.log(MutableHashMap.size(map)) // 1
MutableHashMap.clear(map)
console.log(MutableHashMap.size(map)) // 0
size(self: RcMap<K, A, E>(parameter) self: {
lookup: (key: K) => Effect.Effect<A, E, Scope.Scope>;
context: Context.Context<never>;
scope: Scope.Scope;
idleTimeToLive: (key: K) => Duration.Duration;
capacity: number;
state: State<K, A, 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; <…;
}
RcMap<K, A, E>.state: State<K, A, E>(property) RcMap<K, A, E>.state: {
_tag: "Open";
map: MutableHashMap.MutableHashMap<K, Entry<A, E>>;
}
State<K, A, E>.Open<K, A, E>.map: MutableHashMap.MutableHashMap<K, Entry<A, E>>(property) State<K, A, E>.Open<K, A, E>.map: {
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;
}
self: RcMap<K, A, E>(parameter) self: {
lookup: (key: K) => Effect.Effect<A, E, Scope.Scope>;
context: Context.Context<never>;
scope: Scope.Scope;
idleTimeToLive: (key: K) => Duration.Duration;
capacity: number;
state: State<K, A, 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; <…;
}
RcMap<in out K, in out A, in out E = never>.capacity: numbercapacity) {
return import EffectEffect.const fail: <E>(
error: E
) => Effect<never, E>
Creates an Effect that represents a recoverable error.
When to use
Use to explicitly signal a recoverable error in an Effect.
Details
The error keeps propagating unless it is handled. You can handle tagged
errors with functions like
catchTag
or
catchTags
.
Example (Creating a failed effect)
import { Data, Effect } from "effect"
class OperationFailedError extends Data.TaggedError("OperationFailedError")<{}> {}
// ┌─── Effect<never, OperationFailedError, never>
// ▼
const failure = Effect.fail(
new OperationFailedError()
)
fail(
new import CauseCause.const ExceededCapacityError: new (
message?: string
) => ExceededCapacityError
Constructs an ExceededCapacityError with an optional message.
When to use
Use to create the error value for bounded-resource capacity failures.
Example (Creating an ExceededCapacityError)
import { Cause } from "effect"
const error = new Cause.ExceededCapacityError("Queue full")
console.log(error.message) // "Queue full"
ExceededCapacityError(`RcMap attempted to exceed capacity of ${self: RcMap<K, A, E>(parameter) self: {
lookup: (key: K) => Effect.Effect<A, E, Scope.Scope>;
context: Context.Context<never>;
scope: Scope.Scope;
idleTimeToLive: (key: K) => Duration.Duration;
capacity: number;
state: State<K, A, 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; <…;
}
RcMap<in out K, in out A, in out E = never>.capacity: numbercapacity}`)
) as 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<never>
} else {
let entry: State.Entry<A, E>let entry: {
deferred: Deferred.Deferred<A, E>;
scope: Scope.Closeable;
finalizer: Effect.Effect<void>;
idleTimeToLive: Duration.Duration;
fiber: Fiber.Fiber<void> | undefined;
expiresAt: number;
refCount: number;
}
State<K, A, E>.Entry<A, E>.deferred: Deferred.Deferred<A, E>(property) State<K, A, E>.Entry<A, E>.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; <…;
}
import DeferredDeferred.const makeUnsafe: <
A,
E = never
>() => Deferred<A, E>
Creates an empty Deferred synchronously outside the Effect runtime.
When to use
Use to allocate a Deferred synchronously when direct allocation outside
Effect is required.
Example (Creating a Deferred unsafely)
import { Deferred } from "effect"
const deferred = Deferred.makeUnsafe<number>()
console.log(deferred)
makeUnsafe(),
State<K, A, E>.Entry<A, E>.scope: Scope.Closeable(property) State<K, A, E>.Entry<A, E>.scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
import ScopeScope.const makeUnsafe: (
finalizerStrategy?: "sequential" | "parallel"
) => Closeable
Creates a new Scope synchronously without wrapping it in an Effect.
This is useful when you need a scope immediately but should be used with caution
as it doesn't provide the same safety guarantees as the Effect-wrapped version.
When to use
Use when a scope must be allocated synchronously and the caller will close it
manually.
Example (Creating a scope synchronously)
import { Console, Effect, Exit, Scope } from "effect"
// Create a scope immediately
const scope = Scope.makeUnsafe("sequential")
// Use it in an Effect program
const program = Effect.gen(function*() {
yield* Scope.addFinalizer(scope, Console.log("Cleanup"))
yield* Scope.close(scope, Exit.void)
})
makeUnsafe(),
State<K, A, E>.Entry<A, E>.idleTimeToLive: Duration.Duration(property) State<K, A, E>.Entry<A, E>.idleTimeToLive: {
value: DurationValue;
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;
}
self: RcMap<K, A, E>(parameter) self: {
lookup: (key: K) => Effect.Effect<A, E, Scope.Scope>;
context: Context.Context<never>;
scope: Scope.Scope;
idleTimeToLive: (key: K) => Duration.Duration;
capacity: number;
state: State<K, A, 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; <…;
}
RcMap<K, A, E>.idleTimeToLive: (key: K) => Duration.DurationidleTimeToLive(key: Kkey),
State<K, A, E>.Entry<A, E>.finalizer: Effect.Effect<void, never, never>finalizer: var undefinedundefined as any,
State<K, A, E>.Entry<A, E>.fiber: Fiber.Fiber<void, never> | undefinedfiber: var undefinedundefined,
State<K, A, E>.Entry<A, E>.expiresAt: numberexpiresAt: 0,
State<K, A, E>.Entry<A, E>.refCount: numberrefCount: 1
}
;(let entry: State.Entry<A, E>let entry: {
deferred: Deferred.Deferred<A, E>;
scope: Scope.Closeable;
finalizer: Effect.Effect<void>;
idleTimeToLive: Duration.Duration;
fiber: Fiber.Fiber<void> | undefined;
expiresAt: number;
refCount: number;
}
const release: <K, A, E>(
self: RcMap<K, A, E>,
key: K,
entry: State.Entry<A, E>
) => Effect.Effect<void, never, never>
self: RcMap<K, A, E>(parameter) self: {
lookup: (key: K) => Effect.Effect<A, E, Scope.Scope>;
context: Context.Context<never>;
scope: Scope.Scope;
idleTimeToLive: (key: K) => Duration.Duration;
capacity: number;
state: State<K, A, 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; <…;
}
key: Kkey, let entry: State.Entry<A, E>let entry: {
deferred: Deferred.Deferred<A, E>;
scope: Scope.Closeable;
finalizer: Effect.Effect<void>;
idleTimeToLive: Duration.Duration;
fiber: Fiber.Fiber<void> | undefined;
expiresAt: number;
refCount: number;
}
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>
}
const state: State.Open<K, A, E>const state: {
_tag: "Open";
map: MutableHashMap.MutableHashMap<K, Entry<A, E>>;
}
State<K, A, E>.Open<K, A, E>.map: MutableHashMap.MutableHashMap<K, Entry<A, E>>(property) State<K, A, E>.Open<K, A, E>.map: {
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, let entry: State.Entry<A, E>let entry: {
deferred: Deferred.Deferred<A, E>;
scope: Scope.Closeable;
finalizer: Effect.Effect<void>;
idleTimeToLive: Duration.Duration;
fiber: Fiber.Fiber<void> | undefined;
expiresAt: number;
refCount: number;
}
const context: Map<string, any>context = new var Map: MapConstructor
new <string, any>(iterable?: Iterable<readonly [string, any]> | null | undefined) => Map<string, any> (+3 overloads)
self: RcMap<K, A, E>(parameter) self: {
lookup: (key: K) => Effect.Effect<A, E, Scope.Scope>;
context: Context.Context<never>;
scope: Scope.Scope;
idleTimeToLive: (key: K) => Duration.Duration;
capacity: number;
state: State<K, A, 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; <…;
}
RcMap<in out K, in out A, in out E = never>.context: Context.Context<never>(property) RcMap<in out K, in out A, in out E = never>.context: {
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;
}
Context<never>.mapUnsafe: ReadonlyMap<string, any>mapUnsafe)
const parent: Fiber.Fiber<any, any>const parent: {
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<out A, out E = never>.context: Context.Context<never>(property) Fiber<out A, out E = never>.context: {
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;
}
Context<never>.mapUnsafe: ReadonlyMap<string, any>mapUnsafe.ReadonlyMap<string, any>.forEach(callbackfn: (value: any, key: string, map: ReadonlyMap<string, any>) => void, thisArg?: any): voidforEach((value: anyvalue, key: stringkey) => {
const context: Map<string, any>context.Map<string, any>.set(key: string, value: any): Map<string, any>Adds a new element with a specified key and value to the Map. If an element with the same key already exists, the element will be updated.
set(key: stringkey, value: anyvalue)
})
const context: Map<string, any>context.Map<string, any>.set(key: string, value: any): Map<string, any>Adds a new element with a specified key and value to the Map. If an element with the same key already exists, the element will be updated.
set(import ScopeScope.const Scope: Context.Service<Scope, Scope>const Scope: {
key: string;
Service: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
};
of: (this: void, self: Scope.Scope) => Scope.Scope;
context: (self: Scope.Scope) => Context.Context<Scope.Scope>;
use: (f: (service: Scope.Scope) => Effect.Effect<A, E, R>) => Effect.Effect<A, E, Scope.Scope | R>;
useSync: (f: (service: Scope.Scope) => A) => Effect.Effect<A, never, Scope.Scope>;
Identifier: Identifier;
stack: string | 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; <…;
toString: () => string;
toJSON: () => unknown;
}
A Scope represents a context where resources can be acquired and
automatically cleaned up when the scope is closed. Scopes can use
either sequential or parallel finalization strategies.
Example (Managing scoped resources)
import { Effect, Exit, Scope } from "effect"
const program = Effect.gen(function*() {
const scope = yield* Scope.make("sequential")
// Scope has a strategy and state
console.log(scope.strategy) // "sequential"
console.log(scope.state._tag) // "Open"
// Close the scope
yield* Scope.close(scope, Exit.void)
console.log(scope.state._tag) // "Closed"
})
Service tag for the active resource lifetime.
When to use
Use to access the active lifetime when registering finalizers or sharing
resources with the surrounding scope.
Example (Accessing the scope service)
import { Effect, Scope } from "effect"
const program = Effect.gen(function*() {
// Access the scope from the context
const scope = yield* Scope.Scope
// Use the scope for resource management
yield* Scope.addFinalizer(scope, Effect.log("Cleanup"))
})
// Provide a scope to the program
const scoped = Effect.scoped(program)
Scope.Key<Scope, Scope>.key: stringkey, let entry: State.Entry<A, E>let entry: {
deferred: Deferred.Deferred<A, E>;
scope: Scope.Closeable;
finalizer: Effect.Effect<void>;
idleTimeToLive: Duration.Duration;
fiber: Fiber.Fiber<void> | undefined;
expiresAt: number;
refCount: number;
}
State<K, A, E>.Entry<A, E>.scope: Scope.Closeable(property) State<K, A, E>.Entry<A, E>.scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
self: RcMap<K, A, E>(parameter) self: {
lookup: (key: K) => Effect.Effect<A, E, Scope.Scope>;
context: Context.Context<never>;
scope: Scope.Scope;
idleTimeToLive: (key: K) => Duration.Duration;
capacity: number;
state: State<K, A, 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; <…;
}
RcMap<K, A, E>.lookup: (key: K) => Effect.Effect<A, E, Scope.Scope>lookup(key: Kkey).Pipeable.pipe<Effect.Effect<A, E, Scope.Scope>, Fiber.Fiber<A, E>, Fiber.Fiber<A, E>>(this: Effect.Effect<A, E, Scope.Scope>, ab: (_: Effect.Effect<A, E, Scope.Scope>) => Fiber.Fiber<A, E>, bc: (_: Fiber.Fiber<A, E>) => Fiber.Fiber<A, E>): Fiber.Fiber<A, E> (+21 overloads)pipe(
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(import ContextContext.const makeUnsafe: <Services = never>(
mapUnsafe: ReadonlyMap<string, any>
) => Context<Services>
Creates a Context from an existing service map.
When to use
Use when constructing a low-level Context from a trusted map whose lifecycle
you control.
Gotchas
This is unsafe because later mutation of the provided map can affect the
created Context. Prefer empty, make, add, or merge for normal
Context construction.
Example (Creating a context from a map)
import { Context } from "effect"
// Create a context from a Map (unsafe)
const map = new Map([
["Logger", { log: (msg: string) => console.log(msg) }]
])
const context = Context.makeUnsafe(map)
makeUnsafe(const context: Map<string, any>context)),
import FiberFiber.const runIn: {
(scope: Scope): <A, E>(
self: Fiber<A, E>
) => Fiber<A, E>
<A, E>(self: Fiber<A, E>, scope: Scope): Fiber<
A,
E
>
}
let entry: State.Entry<A, E>let entry: {
deferred: Deferred.Deferred<A, E>;
scope: Scope.Closeable;
finalizer: Effect.Effect<void>;
idleTimeToLive: Duration.Duration;
fiber: Fiber.Fiber<void> | undefined;
expiresAt: number;
refCount: number;
}
State<K, A, E>.Entry<A, E>.scope: Scope.Closeable(property) State<K, A, E>.Entry<A, E>.scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
Fiber<A, E>.addObserver: (cb: (exit: Exit<A, E>) => void) => () => voidaddObserver((exit: Exit.Exit<A, E>exit) => 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(let entry: State.Entry<A, E>let entry: {
deferred: Deferred.Deferred<A, E>;
scope: Scope.Closeable;
finalizer: Effect.Effect<void>;
idleTimeToLive: Duration.Duration;
fiber: Fiber.Fiber<void> | undefined;
expiresAt: number;
refCount: number;
}
State<K, A, E>.Entry<A, E>.deferred: Deferred.Deferred<A, E>(property) State<K, A, E>.Entry<A, E>.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.Exit<A, E>exit))
}
const const scope: Scope.Scopeconst scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
import ContextContext.const getUnsafe: {
<S, I>(service: Key<I, S>): <Services>(
self: Context<Services>
) => S
<Services, S, I>(
self: Context<Services>,
services: Key<I, S>
): S
}
const parent: Fiber.Fiber<any, any>const parent: {
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<out A, out E = never>.context: Context.Context<never>(property) Fiber<out A, out E = never>.context: {
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;
}
import ScopeScope.const Scope: Context.Service<Scope, Scope>const Scope: {
key: string;
Service: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
};
of: (this: void, self: Scope.Scope) => Scope.Scope;
context: (self: Scope.Scope) => Context.Context<Scope.Scope>;
use: (f: (service: Scope.Scope) => Effect.Effect<A, E, R>) => Effect.Effect<A, E, Scope.Scope | R>;
useSync: (f: (service: Scope.Scope) => A) => Effect.Effect<A, never, Scope.Scope>;
Identifier: Identifier;
stack: string | 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; <…;
toString: () => string;
toJSON: () => unknown;
}
A Scope represents a context where resources can be acquired and
automatically cleaned up when the scope is closed. Scopes can use
either sequential or parallel finalization strategies.
Example (Managing scoped resources)
import { Effect, Exit, Scope } from "effect"
const program = Effect.gen(function*() {
const scope = yield* Scope.make("sequential")
// Scope has a strategy and state
console.log(scope.strategy) // "sequential"
console.log(scope.state._tag) // "Open"
// Close the scope
yield* Scope.close(scope, Exit.void)
console.log(scope.state._tag) // "Closed"
})
Service tag for the active resource lifetime.
When to use
Use to access the active lifetime when registering finalizers or sharing
resources with the surrounding scope.
Example (Accessing the scope service)
import { Effect, Scope } from "effect"
const program = Effect.gen(function*() {
// Access the scope from the context
const scope = yield* Scope.Scope
// Use the scope for resource management
yield* Scope.addFinalizer(scope, Effect.log("Cleanup"))
})
// Provide a scope to the program
const scoped = Effect.scoped(program)
Scope)
return import ScopeScope.const addFinalizer: (
scope: Scope,
finalizer: Effect<unknown>
) => Effect<void>
Registers a finalizer effect on a scope.
Details
If the scope is open, the finalizer runs when the scope closes, regardless of
whether the scope closes successfully or with an error. If the scope is
already closed, the finalizer runs immediately.
Example (Adding finalizers)
import { Console, Effect, Exit, Scope } from "effect"
const program = Effect.gen(function*() {
const scope = yield* Scope.make()
// Add simple finalizers
yield* Scope.addFinalizer(scope, Console.log("Cleanup task 1"))
yield* Scope.addFinalizer(scope, Console.log("Cleanup task 2"))
yield* Scope.addFinalizer(scope, Effect.log("Cleanup task 3"))
// Do some work
yield* Console.log("Doing work...")
// Close the scope
yield* Scope.close(scope, Exit.void)
})
addFinalizer(const scope: Scope.Scopeconst scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
let entry: State.Entry<A, E>let entry: {
deferred: Deferred.Deferred<A, E>;
scope: Scope.Closeable;
finalizer: Effect.Effect<void>;
idleTimeToLive: Duration.Duration;
fiber: Fiber.Fiber<void> | undefined;
expiresAt: number;
refCount: number;
}
State<K, A, E>.Entry<A, E>.finalizer: Effect.Effect<void>(property) State<K, A, E>.Entry<A, E>.finalizer: {
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;
}
Pipeable.pipe<Effect.Effect<void, never, never>, Effect.Effect<A, E, never>>(this: Effect.Effect<void, never, never>, ab: (_: Effect.Effect<void, never, never>) => Effect.Effect<A, E, never>): Effect.Effect<A, E, never> (+21 overloads)pipe(
import EffectEffect.const andThen: {
<A, B, E2, R2>(
f: (a: A) => Effect<B, E2, R2>
): <E, R>(
self: Effect<A, E, R>
) => Effect<B, E | E2, R | R2>
<B, E2, R2>(f: Effect<B, E2, R2>): <A, E, R>(
self: Effect<A, E, R>
) => Effect<B, E | E2, R | R2>
<A, E, R, B, E2, R2>(
self: Effect<A, E, R>,
f: (a: A) => Effect<B, E2, R2>
): Effect<B, E | E2, R | R2>
<A, E, R, B, E2, R2>(
self: Effect<A, E, R>,
f: Effect<B, E2, R2>
): Effect<B, E | E2, R | R2>
}
restore: <AX, EX, RX>(
effect: Effect<AX, EX, RX>
) => Effect<AX, EX, RX>
import DeferredDeferred.await<A, E>(self: Deferred<A, E>): Effect<A, E>Retrieves the value of the Deferred, suspending the fiber running the
workflow until the result is available.
When to use
Use to wait for a Deferred to be completed and resume with its success,
failure, defect, or interruption.
Details
Awaiters observe the completion effect stored in the Deferred.
Example (Awaiting a Deferred value)
import { Deferred, Effect } from "effect"
const program = Effect.gen(function*() {
const deferred = yield* Deferred.make<number>()
yield* Deferred.succeed(deferred, 42)
const value = yield* Deferred.await(deferred)
console.log(value) // 42
})
await(let entry: State.Entry<A, E>let entry: {
deferred: Deferred.Deferred<A, E>;
scope: Scope.Closeable;
finalizer: Effect.Effect<void>;
idleTimeToLive: Duration.Duration;
fiber: Fiber.Fiber<void> | undefined;
expiresAt: number;
refCount: number;
}
State<K, A, E>.Entry<A, E>.deferred: Deferred.Deferred<A, E>(property) State<K, A, E>.Entry<A, E>.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; <…;
}