<A, E>(result: Result<A, E>): (
self: TxDeferred<A, E>
) => Effect.Effect<boolean>
<A, E>(
self: TxDeferred<A, E>,
result: Result<A, E>
): Effect.Effect<boolean>Completes the deferred with a Result. Returns true if this was the first
completion, false if already completed.
When to use
Use to complete a TxDeferred with an already computed Result.
Example (Completing with a result)
import { Effect, Result, TxDeferred } from "effect"
const program = Effect.gen(function*() {
const deferred = yield* TxDeferred.make<number, string>()
const first = yield* TxDeferred.done(deferred, Result.succeed(42))
console.log(first) // true
const second = yield* TxDeferred.done(deferred, Result.succeed(99))
console.log(second) // false
})export const const done: {
<A, E>(result: Result<A, E>): (
self: TxDeferred<A, E>
) => Effect.Effect<boolean>
<A, E>(
self: TxDeferred<A, E>,
result: Result<A, E>
): Effect.Effect<boolean>
}
Completes the deferred with a Result. Returns true if this was the first
completion, false if already completed.
When to use
Use to complete a TxDeferred with an already computed Result.
Example (Completing with a result)
import { Effect, Result, TxDeferred } from "effect"
const program = Effect.gen(function*() {
const deferred = yield* TxDeferred.make<number, string>()
const first = yield* TxDeferred.done(deferred, Result.succeed(42))
console.log(first) // true
const second = yield* TxDeferred.done(deferred, Result.succeed(99))
console.log(second) // false
})
done: {
<function (type parameter) A in <A, E>(result: Result<A, E>): (self: TxDeferred<A, E>) => Effect.Effect<boolean>A, function (type parameter) E in <A, E>(result: Result<A, E>): (self: TxDeferred<A, E>) => Effect.Effect<boolean>E>(result: Result<A, E>result: type Result<A, E = never> = Res.Success<A, E> | Res.Failure<A, E>A value that is either Success<A, E> or Failure<A, E>.
When to use
Use when both success and failure should remain available as data and
Option would lose failure information.
Details
- Use
succeed
/
fail
to construct
- Use
match
to fold both branches
- Use
isSuccess
/
isFailure
to narrow the type
E defaults to never, so Result<number> means a result that cannot fail.
Example (Creating and matching a Result)
import { Result } from "effect"
const success = Result.succeed(42)
const failure = Result.fail("something went wrong")
const message = Result.match(success, {
onSuccess: (value) => `Success: ${value}`,
onFailure: (error) => `Error: ${error}`
})
console.log(message)
// Output: "Success: 42"
Namespace containing type-level utilities for extracting the inner types
of a Result.
Example (Extracting inner types)
import type { Result } from "effect"
type R = Result.Result<number, string>
// number
type A = Result.Result.Success<R>
// string
type E = Result.Result.Failure<R>
Result<function (type parameter) A in <A, E>(result: Result<A, E>): (self: TxDeferred<A, E>) => Effect.Effect<boolean>A, function (type parameter) E in <A, E>(result: Result<A, E>): (self: TxDeferred<A, E>) => Effect.Effect<boolean>E>): (self: TxDeferred<A, E>(parameter) self: {
ref: TxRef.TxRef<Option<Result<A, E>>>;
toString: () => string;
toJSON: () => unknown;
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 TxDeferred<in out A, in out E = never>A transactional deferred is a write-once cell readable within transactions.
Readers block (retry the transaction) until a value is committed, and writers
succeed only on the first call; subsequent writes return false.
When to use
Use to coordinate transaction-local readers and one-time completion with a
success or failure result.
Example (Completing a transactional deferred)
import { Effect, TxDeferred } from "effect"
const program = Effect.gen(function*() {
const deferred = yield* TxDeferred.make<number>()
// Complete the deferred
const first = yield* TxDeferred.succeed(deferred, 42)
console.log(first) // true
// Second write is a no-op
const second = yield* TxDeferred.succeed(deferred, 99)
console.log(second) // false
// Read the value
const value = yield* TxDeferred.await(deferred)
console.log(value) // 42
})
TxDeferred<function (type parameter) A in <A, E>(result: Result<A, E>): (self: TxDeferred<A, E>) => Effect.Effect<boolean>A, function (type parameter) E in <A, E>(result: Result<A, E>): (self: TxDeferred<A, E>) => Effect.Effect<boolean>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<boolean>
<function (type parameter) A in <A, E>(self: TxDeferred<A, E>, result: Result<A, E>): Effect.Effect<boolean>A, function (type parameter) E in <A, E>(self: TxDeferred<A, E>, result: Result<A, E>): Effect.Effect<boolean>E>(self: TxDeferred<A, E>(parameter) self: {
ref: TxRef.TxRef<Option<Result<A, E>>>;
toString: () => string;
toJSON: () => unknown;
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 TxDeferred<in out A, in out E = never>A transactional deferred is a write-once cell readable within transactions.
Readers block (retry the transaction) until a value is committed, and writers
succeed only on the first call; subsequent writes return false.
When to use
Use to coordinate transaction-local readers and one-time completion with a
success or failure result.
Example (Completing a transactional deferred)
import { Effect, TxDeferred } from "effect"
const program = Effect.gen(function*() {
const deferred = yield* TxDeferred.make<number>()
// Complete the deferred
const first = yield* TxDeferred.succeed(deferred, 42)
console.log(first) // true
// Second write is a no-op
const second = yield* TxDeferred.succeed(deferred, 99)
console.log(second) // false
// Read the value
const value = yield* TxDeferred.await(deferred)
console.log(value) // 42
})
TxDeferred<function (type parameter) A in <A, E>(self: TxDeferred<A, E>, result: Result<A, E>): Effect.Effect<boolean>A, function (type parameter) E in <A, E>(self: TxDeferred<A, E>, result: Result<A, E>): Effect.Effect<boolean>E>, result: Result<A, E>result: type Result<A, E = never> = Res.Success<A, E> | Res.Failure<A, E>A value that is either Success<A, E> or Failure<A, E>.
When to use
Use when both success and failure should remain available as data and
Option would lose failure information.
Details
- Use
succeed
/
fail
to construct
- Use
match
to fold both branches
- Use
isSuccess
/
isFailure
to narrow the type
E defaults to never, so Result<number> means a result that cannot fail.
Example (Creating and matching a Result)
import { Result } from "effect"
const success = Result.succeed(42)
const failure = Result.fail("something went wrong")
const message = Result.match(success, {
onSuccess: (value) => `Success: ${value}`,
onFailure: (error) => `Error: ${error}`
})
console.log(message)
// Output: "Success: 42"
Namespace containing type-level utilities for extracting the inner types
of a Result.
Example (Extracting inner types)
import type { Result } from "effect"
type R = Result.Result<number, string>
// number
type A = Result.Result.Success<R>
// string
type E = Result.Result.Failure<R>
Result<function (type parameter) A in <A, E>(self: TxDeferred<A, E>, result: Result<A, E>): Effect.Effect<boolean>A, function (type parameter) E in <A, E>(self: TxDeferred<A, E>, result: Result<A, E>): Effect.Effect<boolean>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<boolean>
} = dual<(...args: Array<any>) => any, <A, E>(self: TxDeferred<A, E>, result: Result<A, E>) => Effect.Effect<boolean>>(arity: 2, body: <A, E>(self: TxDeferred<A, E>, result: Result<A, E>) => Effect.Effect<boolean>): ((...args: Array<any>) => any) & (<A, E>(self: TxDeferred<A, E>, result: Result<A, E>) => Effect.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: TxDeferred<A, E>, result: Result<A, E>): Effect.Effect<boolean>A, function (type parameter) E in <A, E>(self: TxDeferred<A, E>, result: Result<A, E>): Effect.Effect<boolean>E>(self: TxDeferred<A, E>(parameter) self: {
ref: TxRef.TxRef<Option<Result<A, E>>>;
toString: () => string;
toJSON: () => unknown;
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 TxDeferred<in out A, in out E = never>A transactional deferred is a write-once cell readable within transactions.
Readers block (retry the transaction) until a value is committed, and writers
succeed only on the first call; subsequent writes return false.
When to use
Use to coordinate transaction-local readers and one-time completion with a
success or failure result.
Example (Completing a transactional deferred)
import { Effect, TxDeferred } from "effect"
const program = Effect.gen(function*() {
const deferred = yield* TxDeferred.make<number>()
// Complete the deferred
const first = yield* TxDeferred.succeed(deferred, 42)
console.log(first) // true
// Second write is a no-op
const second = yield* TxDeferred.succeed(deferred, 99)
console.log(second) // false
// Read the value
const value = yield* TxDeferred.await(deferred)
console.log(value) // 42
})
TxDeferred<function (type parameter) A in <A, E>(self: TxDeferred<A, E>, result: Result<A, E>): Effect.Effect<boolean>A, function (type parameter) E in <A, E>(self: TxDeferred<A, E>, result: Result<A, E>): Effect.Effect<boolean>E>, result: Result<A, E>result: type Result<A, E = never> = Res.Success<A, E> | Res.Failure<A, E>A value that is either Success<A, E> or Failure<A, E>.
When to use
Use when both success and failure should remain available as data and
Option would lose failure information.
Details
- Use
succeed
/
fail
to construct
- Use
match
to fold both branches
- Use
isSuccess
/
isFailure
to narrow the type
E defaults to never, so Result<number> means a result that cannot fail.
Example (Creating and matching a Result)
import { Result } from "effect"
const success = Result.succeed(42)
const failure = Result.fail("something went wrong")
const message = Result.match(success, {
onSuccess: (value) => `Success: ${value}`,
onFailure: (error) => `Error: ${error}`
})
console.log(message)
// Output: "Success: 42"
Namespace containing type-level utilities for extracting the inner types
of a Result.
Example (Extracting inner types)
import type { Result } from "effect"
type R = Result.Result<number, string>
// number
type A = Result.Result.Success<R>
// string
type E = Result.Result.Failure<R>
Result<function (type parameter) A in <A, E>(self: TxDeferred<A, E>, result: Result<A, E>): Effect.Effect<boolean>A, function (type parameter) E in <A, E>(self: TxDeferred<A, E>, result: Result<A, E>): Effect.Effect<boolean>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<boolean> =>
import TxRefTxRef.const modify: {
<A, R>(
f: (
current: NoInfer<A>
) => [returnValue: R, newValue: A]
): (self: TxRef<A>) => Effect.Effect<R>
<A, R>(
self: TxRef<A>,
f: (
current: A
) => [returnValue: R, newValue: A]
): Effect.Effect<R>
}
self: TxDeferred<A, E>(parameter) self: {
ref: TxRef.TxRef<Option<Result<A, E>>>;
toString: () => string;
toJSON: () => unknown;
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; <…;
}
TxDeferred<A, E>.ref: TxRef.TxRef<Option<Result<A, E>>>(property) TxDeferred<A, E>.ref: {
version: number;
pending: Map<unknown, () => void>;
value: 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; <…;
}
current: Option<Result<A, E>>current) => {
if (import OO.const isSome: <A>(
self: Option<A>
) => self is Some<A>
Checks whether an Option contains a value (Some).
When to use
Use when you need to branch on a present Option before accessing .value.
Details
- Acts as a type guard, narrowing to
Some<A>
Example (Checking for Some)
import { Option } from "effect"
console.log(Option.isSome(Option.some(1)))
// Output: true
console.log(Option.isSome(Option.none()))
// Output: false
isSome(current: Option<Result<A, E>>current)) {
return [false, current: O.Some<Result<A, E>>(parameter) current: {
_tag: "Some";
_op: "Some";
value: A;
valueOrUndefined: A;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
import OO.const some: <A>(value: A) => Option<A>Wraps the given value into an Option to represent its presence.
When to use
Use to wrap a known present value as Option
- Returning a successful result from a partial function
Details
- Always returns
Some<A>
- Does not filter
null or undefined; use
fromNullishOr
for that
Example (Wrapping a value)
import { Option } from "effect"
// ┌─── Option<number>
// ▼
const value = Option.some(1)
console.log(value)
// Output: { _id: 'Option', _tag: 'Some', value: 1 }
some(result: Result<A, E>result)]
})
)