<A, E>(effect: Effect<A, E>): (self: Deferred<A, E>) => Effect<boolean>
<A, E>(self: Deferred<A, E>, effect: Effect<A, E>): Effect<boolean>Attempts to complete the Deferred with the specified effect directly.
When to use
Use to store an already environment-free effect as the completion without running it during completion.
Details
The returned effect succeeds with true when this call completed the
Deferred, or false if it was already completed.
Gotchas
The supplied effect is not memoized by completeWith; each awaiter may run
the stored effect independently.
Example (Completing a Deferred with an effect)
import { Deferred, Effect } from "effect"
const program = Effect.gen(function*() {
const deferred = yield* Deferred.make<number>()
const completed = yield* Deferred.completeWith(deferred, Effect.succeed(42))
console.log(completed) // true
const value = yield* Deferred.await(deferred)
console.log(value) // 42
})export const const completeWith: {
<A, E>(effect: Effect<A, E>): (
self: Deferred<A, E>
) => Effect<boolean>
<A, E>(
self: Deferred<A, E>,
effect: Effect<A, E>
): Effect<boolean>
}
Attempts to complete the Deferred with the specified effect directly.
When to use
Use to store an already environment-free effect as the completion without
running it during completion.
Details
The returned effect succeeds with true when this call completed the
Deferred, or false if it was already completed.
Gotchas
The supplied effect is not memoized by completeWith; each awaiter may run
the stored effect independently.
Example (Completing a Deferred with an effect)
import { Deferred, Effect } from "effect"
const program = Effect.gen(function*() {
const deferred = yield* Deferred.make<number>()
const completed = yield* Deferred.completeWith(deferred, Effect.succeed(42))
console.log(completed) // true
const value = yield* Deferred.await(deferred)
console.log(value) // 42
})
completeWith: {
<function (type parameter) A in <A, E>(effect: Effect<A, E>): (self: Deferred<A, E>) => Effect<boolean>A, function (type parameter) E in <A, E>(effect: Effect<A, E>): (self: Deferred<A, E>) => Effect<boolean>E>(effect: Effect<A, E>(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;
}
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>(effect: Effect<A, E>): (self: Deferred<A, E>) => Effect<boolean>A, function (type parameter) E in <A, E>(effect: Effect<A, E>): (self: Deferred<A, E>) => Effect<boolean>E>): (self: Deferred<A, E>(parameter) self: {
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; <…;
}
interface Deferred<in out A, in out E = never>A Deferred represents an asynchronous variable that can be set exactly
once, with the ability for an arbitrary number of fibers to suspend (by
calling Deferred.await) and automatically resume when the variable is set.
When to use
Use to coordinate multiple fibers around a value or failure that will be
supplied exactly once.
Example (Creating a Deferred for inter-fiber communication)
import { Deferred, Effect, Fiber } from "effect"
// Create and use a Deferred for inter-fiber communication
const program = Effect.gen(function*() {
// Create a Deferred that will hold a string value
const deferred: Deferred.Deferred<string> = yield* Deferred.make<string>()
// Fork a fiber that will set the deferred value
const producer = yield* Effect.forkChild(
Effect.gen(function*() {
yield* Effect.sleep("100 millis")
yield* Deferred.succeed(deferred, "Hello, World!")
})
)
// Fork a fiber that will await the deferred value
const consumer = yield* Effect.forkChild(
Effect.gen(function*() {
const value = yield* Deferred.await(deferred)
console.log("Received:", value)
return value
})
)
// Wait for both fibers to complete
yield* Fiber.join(producer)
const result = yield* Fiber.join(consumer)
return result
})
Companion namespace containing type-level metadata for Deferred.
When to use
Use to reference type-level metadata associated with Deferred.
Deferred<function (type parameter) A in <A, E>(effect: Effect<A, E>): (self: Deferred<A, E>) => Effect<boolean>A, function (type parameter) E in <A, E>(effect: Effect<A, E>): (self: Deferred<A, E>) => Effect<boolean>E>) => 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<boolean>
<function (type parameter) A in <A, E>(self: Deferred<A, E>, effect: Effect<A, E>): Effect<boolean>A, function (type parameter) E in <A, E>(self: Deferred<A, E>, effect: Effect<A, E>): Effect<boolean>E>(self: Deferred<A, E>(parameter) self: {
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; <…;
}
interface Deferred<in out A, in out E = never>A Deferred represents an asynchronous variable that can be set exactly
once, with the ability for an arbitrary number of fibers to suspend (by
calling Deferred.await) and automatically resume when the variable is set.
When to use
Use to coordinate multiple fibers around a value or failure that will be
supplied exactly once.
Example (Creating a Deferred for inter-fiber communication)
import { Deferred, Effect, Fiber } from "effect"
// Create and use a Deferred for inter-fiber communication
const program = Effect.gen(function*() {
// Create a Deferred that will hold a string value
const deferred: Deferred.Deferred<string> = yield* Deferred.make<string>()
// Fork a fiber that will set the deferred value
const producer = yield* Effect.forkChild(
Effect.gen(function*() {
yield* Effect.sleep("100 millis")
yield* Deferred.succeed(deferred, "Hello, World!")
})
)
// Fork a fiber that will await the deferred value
const consumer = yield* Effect.forkChild(
Effect.gen(function*() {
const value = yield* Deferred.await(deferred)
console.log("Received:", value)
return value
})
)
// Wait for both fibers to complete
yield* Fiber.join(producer)
const result = yield* Fiber.join(consumer)
return result
})
Companion namespace containing type-level metadata for Deferred.
When to use
Use to reference type-level metadata associated with Deferred.
Deferred<function (type parameter) A in <A, E>(self: Deferred<A, E>, effect: Effect<A, E>): Effect<boolean>A, function (type parameter) E in <A, E>(self: Deferred<A, E>, effect: Effect<A, E>): Effect<boolean>E>, effect: Effect<A, E>(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;
}
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: Deferred<A, E>, effect: Effect<A, E>): Effect<boolean>A, function (type parameter) E in <A, E>(self: Deferred<A, E>, effect: Effect<A, E>): Effect<boolean>E>): 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<boolean>
} = dual<(...args: Array<any>) => any, <A, E>(self: Deferred<A, E>, effect: Effect<A, E>) => Effect<boolean>>(arity: 2, body: <A, E>(self: Deferred<A, E>, effect: Effect<A, E>) => Effect<boolean>): ((...args: Array<any>) => any) & (<A, E>(self: Deferred<A, E>, effect: Effect<A, E>) => Effect<boolean>) (+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>(self: Deferred<A, E>, effect: Effect<A, E>): Effect<boolean>A, function (type parameter) E in <A, E>(self: Deferred<A, E>, effect: Effect<A, E>): Effect<boolean>E>(self: Deferred<A, E>(parameter) self: {
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; <…;
}
interface Deferred<in out A, in out E = never>A Deferred represents an asynchronous variable that can be set exactly
once, with the ability for an arbitrary number of fibers to suspend (by
calling Deferred.await) and automatically resume when the variable is set.
When to use
Use to coordinate multiple fibers around a value or failure that will be
supplied exactly once.
Example (Creating a Deferred for inter-fiber communication)
import { Deferred, Effect, Fiber } from "effect"
// Create and use a Deferred for inter-fiber communication
const program = Effect.gen(function*() {
// Create a Deferred that will hold a string value
const deferred: Deferred.Deferred<string> = yield* Deferred.make<string>()
// Fork a fiber that will set the deferred value
const producer = yield* Effect.forkChild(
Effect.gen(function*() {
yield* Effect.sleep("100 millis")
yield* Deferred.succeed(deferred, "Hello, World!")
})
)
// Fork a fiber that will await the deferred value
const consumer = yield* Effect.forkChild(
Effect.gen(function*() {
const value = yield* Deferred.await(deferred)
console.log("Received:", value)
return value
})
)
// Wait for both fibers to complete
yield* Fiber.join(producer)
const result = yield* Fiber.join(consumer)
return result
})
Companion namespace containing type-level metadata for Deferred.
When to use
Use to reference type-level metadata associated with Deferred.
Deferred<function (type parameter) A in <A, E>(self: Deferred<A, E>, effect: Effect<A, E>): Effect<boolean>A, function (type parameter) E in <A, E>(self: Deferred<A, E>, effect: Effect<A, E>): Effect<boolean>E>, effect: Effect<A, E>(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;
}
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: Deferred<A, E>, effect: Effect<A, E>): Effect<boolean>A, function (type parameter) E in <A, E>(self: Deferred<A, E>, effect: Effect<A, E>): Effect<boolean>E>): 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<boolean> =>
import internalEffectinternalEffect.const sync: <A>(
thunk: LazyArg<A>
) => Effect.Effect<A>
const doneUnsafe: <A, E>(
self: Deferred<A, E>,
effect: Effect<A, E>
) => boolean
Attempts to complete the Deferred synchronously with the specified
completion effect.
When to use
Use to complete a Deferred synchronously in low-level code that already has
the completion effect.
Details
This mutates the Deferred directly and should be reserved for low-level
code; prefer the effectful completion APIs when possible. Returns true if
this call completed the Deferred, or false if it was already completed.
Example (Completing a Deferred unsafely)
import { Deferred, Effect } from "effect"
const deferred = Deferred.makeUnsafe<number>()
const success = Deferred.doneUnsafe(deferred, Effect.succeed(42))
console.log(success) // true
doneUnsafe(self: Deferred<A, E>(parameter) self: {
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; <…;
}
effect: Effect<A, E>(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;
}