<I, S, E2, R2>(service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): <
A,
E,
R
>(
self: Effect<A, E, R>
) => Effect<A, E | E2, Exclude<R, I> | R2>
<A, E, R, I, S, E2, R2>(
self: Effect<A, E, R>,
service: Context.Key<I, S>,
acquire: Effect<S, E2, R2>
): Effect<A, E | E2, Exclude<R, I> | R2>Provides one service to an effect using an effectful acquisition.
When to use
Use when the service implementation must be created by an effect and its acquisition failure should remain in the returned effect.
Details
provideServiceEffect runs the acquisition effect to produce the service
implementation, removes that service from the wrapped effect's requirements,
and leaves any other requirements to be provided later. Acquisition failures
are included in the returned effect's error channel.
Example (Providing a service with an effect)
import { Console, Context, Effect } from "effect"
// Define a database connection service
interface DatabaseConnection {
readonly query: (sql: string) => Effect.Effect<string>
}
const Database = Context.Service<DatabaseConnection>("Database")
// Effect that creates a database connection
const createConnection = Effect.gen(function*() {
yield* Console.log("Establishing database connection...")
yield* Effect.sleep("100 millis") // Simulate connection time
yield* Console.log("Database connected!")
return {
query: (sql: string) => Effect.succeed(`Result for: ${sql}`)
}
})
const program = Effect.gen(function*() {
const db = yield* Effect.service(Database)
return yield* db.query("SELECT * FROM users")
})
// Provide the service through an effect
const withDatabase = Effect.provideServiceEffect(
program,
Database,
createConnection
)
Effect.runPromise(withDatabase).then(console.log)
// Output:
// Establishing database connection...
// Database connected!
// Result for: SELECT * FROM usersexport const const provideServiceEffect: {
<I, S, E2, R2>(
service: Context.Key<I, S>,
acquire: Effect<S, E2, R2>
): <A, E, R>(
self: Effect<A, E, R>
) => Effect<A, E | E2, Exclude<R, I> | R2>
<A, E, R, I, S, E2, R2>(
self: Effect<A, E, R>,
service: Context.Key<I, S>,
acquire: Effect<S, E2, R2>
): Effect<A, E | E2, Exclude<R, I> | R2>
}
Provides one service to an effect using an effectful acquisition.
When to use
Use when the service implementation must be created by an effect and its
acquisition failure should remain in the returned effect.
Details
provideServiceEffect runs the acquisition effect to produce the service
implementation, removes that service from the wrapped effect's requirements,
and leaves any other requirements to be provided later. Acquisition failures
are included in the returned effect's error channel.
Example (Providing a service with an effect)
import { Console, Context, Effect } from "effect"
// Define a database connection service
interface DatabaseConnection {
readonly query: (sql: string) => Effect.Effect<string>
}
const Database = Context.Service<DatabaseConnection>("Database")
// Effect that creates a database connection
const createConnection = Effect.gen(function*() {
yield* Console.log("Establishing database connection...")
yield* Effect.sleep("100 millis") // Simulate connection time
yield* Console.log("Database connected!")
return {
query: (sql: string) => Effect.succeed(`Result for: ${sql}`)
}
})
const program = Effect.gen(function*() {
const db = yield* Effect.service(Database)
return yield* db.query("SELECT * FROM users")
})
// Provide the service through an effect
const withDatabase = Effect.provideServiceEffect(
program,
Database,
createConnection
)
Effect.runPromise(withDatabase).then(console.log)
// Output:
// Establishing database connection...
// Database connected!
// Result for: SELECT * FROM users
provideServiceEffect: {
<function (type parameter) I in <I, S, E2, R2>(service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E | E2, Exclude<R, I> | R2>I, function (type parameter) S in <I, S, E2, R2>(service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E | E2, Exclude<R, I> | R2>S, function (type parameter) E2 in <I, S, E2, R2>(service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E | E2, Exclude<R, I> | R2>E2, function (type parameter) R2 in <I, S, E2, R2>(service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E | E2, Exclude<R, I> | R2>R2>(
service: Context.Key<I, S>(parameter) service: {
Identifier: Identifier;
Service: Shape;
key: string;
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;
}
import ContextContext.interface Key<out Identifier, out Shape>Typed identifier for a service stored in a Context.
When to use
Use as the typed handle for storing, retrieving, and requiring a specific
service in a Context.
Details
Identifier tracks the requirement in Effect types, while Shape is the
service implementation retrieved by the key. A key is also an Effect value,
so yielding it inside Effect.gen retrieves the service from the current
fiber context.
Key<function (type parameter) I in <I, S, E2, R2>(service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E | E2, Exclude<R, I> | R2>I, function (type parameter) S in <I, S, E2, R2>(service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E | E2, Exclude<R, I> | R2>S>,
acquire: Effect<S, E2, R2>(parameter) acquire: {
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) S in <I, S, E2, R2>(service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E | E2, Exclude<R, I> | R2>S, function (type parameter) E2 in <I, S, E2, R2>(service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E | E2, Exclude<R, I> | R2>E2, function (type parameter) R2 in <I, S, E2, R2>(service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E | E2, Exclude<R, I> | R2>R2>
): <function (type parameter) A in <A, E, R>(self: Effect<A, E, R>): Effect<A, E | E2, Exclude<R, I> | R2>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A, E | E2, Exclude<R, I> | R2>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<A, E | E2, Exclude<R, I> | R2>R>(self: Effect<A, E, R>(parameter) self: {
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, R>(self: Effect<A, E, R>): Effect<A, E | E2, Exclude<R, I> | R2>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A, E | E2, Exclude<R, I> | R2>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<A, E | E2, Exclude<R, I> | R2>R>) => 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: Effect<A, E, R>): Effect<A, E | E2, Exclude<R, I> | R2>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A, E | E2, Exclude<R, I> | R2>E | function (type parameter) E2 in <I, S, E2, R2>(service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E | E2, Exclude<R, I> | R2>E2, type Exclude<T, U> = T extends U
? never
: T
Exclude from T those types that are assignable to U
Exclude<function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<A, E | E2, Exclude<R, I> | R2>R, function (type parameter) I in <I, S, E2, R2>(service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E | E2, Exclude<R, I> | R2>I> | function (type parameter) R2 in <I, S, E2, R2>(service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E | E2, Exclude<R, I> | R2>R2>
<function (type parameter) A in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>A, function (type parameter) E in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>E, function (type parameter) R in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>R, function (type parameter) I in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>I, function (type parameter) S in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>S, function (type parameter) E2 in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>E2, function (type parameter) R2 in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>R2>(
self: Effect<A, E, R>(parameter) self: {
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, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>A, function (type parameter) E in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>E, function (type parameter) R in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>R>,
service: Context.Key<I, S>(parameter) service: {
Identifier: Identifier;
Service: Shape;
key: string;
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;
}
import ContextContext.interface Key<out Identifier, out Shape>Typed identifier for a service stored in a Context.
When to use
Use as the typed handle for storing, retrieving, and requiring a specific
service in a Context.
Details
Identifier tracks the requirement in Effect types, while Shape is the
service implementation retrieved by the key. A key is also an Effect value,
so yielding it inside Effect.gen retrieves the service from the current
fiber context.
Key<function (type parameter) I in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>I, function (type parameter) S in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>S>,
acquire: Effect<S, E2, R2>(parameter) acquire: {
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) S in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>S, function (type parameter) E2 in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>E2, function (type parameter) R2 in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>R2>
): 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, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>A, function (type parameter) E in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>E | function (type parameter) E2 in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>E2, type Exclude<T, U> = T extends U
? never
: T
Exclude from T those types that are assignable to U
Exclude<function (type parameter) R in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>R, function (type parameter) I in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>I> | function (type parameter) R2 in <A, E, R, I, S, E2, R2>(self: Effect<A, E, R>, service: Context.Key<I, S>, acquire: Effect<S, E2, R2>): Effect<A, E | E2, Exclude<R, I> | R2>R2>
} = import internalinternal.const provideServiceEffect: {
<I, S, E2, R2>(
service: Context.Key<I, S>,
acquire: Effect.Effect<S, E2, R2>
): <A, E, R>(
self: Effect.Effect<A, E, R>
) => Effect.Effect<
A,
E | E2,
Exclude<R, I> | R2
>
<A, E, R, I, S, E2, R2>(
self: Effect.Effect<A, E, R>,
service: Context.Key<I, S>,
acquire: Effect.Effect<S, E2, R2>
): Effect.Effect<A, E | E2, Exclude<R, I> | R2>
}