<A, E, R>(update: (a: A) => Effect.Effect<A, E, R>): (
self: SubscriptionRef<A>
) => Effect.Effect<A, E, R>
<A, E, R>(
self: SubscriptionRef<A>,
update: (a: A) => Effect.Effect<A, E, R>
): Effect.Effect<A, E, R>Retrieves the current value and updates it atomically with the result of applying an effectful function, notifying subscribers of the change.
Example (Getting and updating with an effect)
import { Effect, SubscriptionRef } from "effect"
const program = Effect.gen(function*() {
const ref = yield* SubscriptionRef.make(10)
const oldValue = yield* SubscriptionRef.getAndUpdateEffect(
ref,
(n) => Effect.succeed(n + 5)
)
console.log("Old value:", oldValue)
const newValue = yield* SubscriptionRef.get(ref)
console.log("New value:", newValue)
})export const const getAndUpdateEffect: {
<A, E, R>(
update: (a: A) => Effect.Effect<A, E, R>
): (
self: SubscriptionRef<A>
) => Effect.Effect<A, E, R>
<A, E, R>(
self: SubscriptionRef<A>,
update: (a: A) => Effect.Effect<A, E, R>
): Effect.Effect<A, E, R>
}
Retrieves the current value and updates it atomically with the result of
applying an effectful function, notifying subscribers of the change.
Example (Getting and updating with an effect)
import { Effect, SubscriptionRef } from "effect"
const program = Effect.gen(function*() {
const ref = yield* SubscriptionRef.make(10)
const oldValue = yield* SubscriptionRef.getAndUpdateEffect(
ref,
(n) => Effect.succeed(n + 5)
)
console.log("Old value:", oldValue)
const newValue = yield* SubscriptionRef.get(ref)
console.log("New value:", newValue)
})
getAndUpdateEffect: {
<function (type parameter) A in <A, E, R>(update: (a: A) => Effect.Effect<A, E, R>): (self: SubscriptionRef<A>) => Effect.Effect<A, E, R>A, function (type parameter) E in <A, E, R>(update: (a: A) => Effect.Effect<A, E, R>): (self: SubscriptionRef<A>) => Effect.Effect<A, E, R>E, function (type parameter) R in <A, E, R>(update: (a: A) => Effect.Effect<A, E, R>): (self: SubscriptionRef<A>) => Effect.Effect<A, E, R>R>(update: (a: A) => Effect.Effect<A, E, R>update: (a: Aa: function (type parameter) A in <A, E, R>(update: (a: A) => Effect.Effect<A, E, R>): (self: SubscriptionRef<A>) => Effect.Effect<A, E, R>A) => 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, R>(update: (a: A) => Effect.Effect<A, E, R>): (self: SubscriptionRef<A>) => Effect.Effect<A, E, R>A, function (type parameter) E in <A, E, R>(update: (a: A) => Effect.Effect<A, E, R>): (self: SubscriptionRef<A>) => Effect.Effect<A, E, R>E, function (type parameter) R in <A, E, R>(update: (a: A) => Effect.Effect<A, E, R>): (self: SubscriptionRef<A>) => Effect.Effect<A, E, R>R>): (self: SubscriptionRef<A>(parameter) self: {
value: A;
semaphore: Semaphore.Semaphore;
pubsub: PubSub.PubSub<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; <…;
}
interface SubscriptionRef<in out A>A mutable reference whose updates are serialized and published to
subscribers.
When to use
Use to observe the current value and subsequent updates as a
stream.
The SubscriptionRef namespace containing type definitions associated with
subscription references.
SubscriptionRef<function (type parameter) A in <A, E, R>(update: (a: A) => Effect.Effect<A, E, R>): (self: SubscriptionRef<A>) => Effect.Effect<A, E, R>A>) => 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, R>(update: (a: A) => Effect.Effect<A, E, R>): (self: SubscriptionRef<A>) => Effect.Effect<A, E, R>A, function (type parameter) E in <A, E, R>(update: (a: A) => Effect.Effect<A, E, R>): (self: SubscriptionRef<A>) => Effect.Effect<A, E, R>E, function (type parameter) R in <A, E, R>(update: (a: A) => Effect.Effect<A, E, R>): (self: SubscriptionRef<A>) => Effect.Effect<A, E, R>R>
<function (type parameter) A in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<A, E, R>A, function (type parameter) E in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<A, E, R>E, function (type parameter) R in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<A, E, R>R>(self: SubscriptionRef<A>(parameter) self: {
value: A;
semaphore: Semaphore.Semaphore;
pubsub: PubSub.PubSub<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; <…;
}
interface SubscriptionRef<in out A>A mutable reference whose updates are serialized and published to
subscribers.
When to use
Use to observe the current value and subsequent updates as a
stream.
The SubscriptionRef namespace containing type definitions associated with
subscription references.
SubscriptionRef<function (type parameter) A in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<A, E, R>A>, update: (a: A) => Effect.Effect<A, E, R>update: (a: Aa: function (type parameter) A in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<A, E, R>A) => 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, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<A, E, R>A, function (type parameter) E in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<A, E, R>E, function (type parameter) R in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<A, E, R>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) A in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<A, E, R>A, function (type parameter) E in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<A, E, R>E, function (type parameter) R in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<A, E, R>R>
} = dual<(...args: Array<any>) => any, <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>) => Effect.Effect<Effect.Effect<A, E, R>, never, never>>(arity: 2, body: <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>) => Effect.Effect<Effect.Effect<A, E, R>, never, never>): ((...args: Array<any>) => any) & (<A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>) => Effect.Effect<Effect.Effect<A, E, R>, never, never>) (+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) A in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<Effect.Effect<A, E, R>, never, never>A, function (type parameter) E in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<Effect.Effect<A, E, R>, never, never>E, function (type parameter) R in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<Effect.Effect<A, E, R>, never, never>R>(
self: SubscriptionRef<A>(parameter) self: {
value: A;
semaphore: Semaphore.Semaphore;
pubsub: PubSub.PubSub<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; <…;
}
interface SubscriptionRef<in out A>A mutable reference whose updates are serialized and published to
subscribers.
When to use
Use to observe the current value and subsequent updates as a
stream.
The SubscriptionRef namespace containing type definitions associated with
subscription references.
SubscriptionRef<function (type parameter) A in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<Effect.Effect<A, E, R>, never, never>A>,
update: (a: A) => Effect.Effect<A, E, R>update: (a: Aa: function (type parameter) A in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<Effect.Effect<A, E, R>, never, never>A) => 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, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<Effect.Effect<A, E, R>, never, never>A, function (type parameter) E in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<Effect.Effect<A, E, R>, never, never>E, function (type parameter) R in <A, E, R>(self: SubscriptionRef<A>, update: (a: A) => Effect.Effect<A, E, R>): Effect.Effect<Effect.Effect<A, E, R>, never, never>R>
) =>
self: SubscriptionRef<A>(parameter) self: {
value: A;
semaphore: Semaphore.Semaphore;
pubsub: PubSub.PubSub<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; <…;
}
SubscriptionRef<in out A>.semaphore: Semaphore.Semaphore(property) SubscriptionRef<in out A>.semaphore: {
resize: (this: Semaphore, permits: number) => Effect.Effect<void>;
withPermits: (this: Semaphore, permits: number) => <A, E, R>(self: Effect.Effect<A, E, R>) => Effect.Effect<A, E, R>;
withPermit: <A, E, R>(self: Effect.Effect<A, E, R>) => Effect.Effect<A, E, R>;
withPermitsIfAvailable: (this: Semaphore, permits: number) => <A, E, R>(self: Effect.Effect<A, E, R>) => Effect.Effect<Option.Option<A>, E, R>;
take: (this: Semaphore, permits: number) => Effect.Effect<number>;
release: (this: Semaphore, permits: number) => Effect.Effect<number>;
releaseAll: Effect.Effect<number>;
}
Semaphore.withPermit<A, E, R>(self: Effect.Effect<A, E, R>): Effect.Effect<A, E, R>Runs an effect with the given number of permits and releases the permits
when the effect completes.
When to use
Use to run an effect while holding exactly one semaphore permit.
Details
This function acquires the specified number of permits before executing
the provided effect. Once the effect finishes, the permits are released.
If insufficient permits are available, the function will wait until they
are released by other tasks.
withPermit(import EffectEffect.const sync: <A>(
thunk: LazyArg<A>
) => Effect<A>
Creates an Effect that represents a synchronous side-effectful computation.
When to use
Use when you need to wrap a synchronous side-effectful operation that is not
expected to throw.
Details
The provided function is evaluated lazily when the effect runs.
Gotchas
The function must not throw. If it throws, the thrown value is treated as a
defect, not as a typed failure. Use try when throwing is expected.
Example (Capturing synchronous logging in an Effect)
import { Effect } from "effect"
const log = (message: string) =>
Effect.sync(() => {
console.log(message) // side effect
})
// ┌─── Effect<void, never, never>
// ▼
const program = log("Hello, World!")
sync(() => {
const const current: Acurrent = self: SubscriptionRef<A>(parameter) self: {
value: A;
semaphore: Semaphore.Semaphore;
pubsub: PubSub.PubSub<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; <…;
}
SubscriptionRef<A>.value: Avalue
return 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>
}
update: (a: A) => Effect.Effect<A, E, R>update(const current: Acurrent), (newValue: AnewValue) => {
const setUnsafe: <A>(
self: SubscriptionRef<A>,
value: A
) => void
self: SubscriptionRef<A>(parameter) self: {
value: A;
semaphore: Semaphore.Semaphore;
pubsub: PubSub.PubSub<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; <…;
}
newValue: AnewValue)
return const current: Acurrent
})
})))