<I, S>(service: Context.Key<I, S>): {
(implementation: S): <A, E, R>(
self: Effect<A, E, R>
) => Effect<A, E, Exclude<R, I>>
<A, E, R>(self: Effect<A, E, R>, implementation: S): Effect<
A,
E,
Exclude<R, I>
>
}
<I, S>(service: Context.Key<I, S>, implementation: S): <A, E, R>(
self: Effect<A, E, R>
) => Effect<A, E, Exclude<R, I>>
<A, E, R, I, S>(
self: Effect<A, E, R>,
service: Context.Key<I, S>,
implementation: S
): Effect<A, E, Exclude<R, I>>Provides one concrete service implementation to an effect.
When to use
Use to satisfy one service requirement with an already-built implementation.
Details
The service requirement identified by the Context.Key is removed from the
effect requirements after the implementation is provided.
Example (Providing a service value)
import { Console, Context, Effect } from "effect"
// Define a service for configuration
const Config = Context.Service<{
apiUrl: string
timeout: number
}>("Config")
const fetchData = Effect.gen(function*() {
const config = yield* Effect.service(Config)
yield* Console.log(`Fetching from: ${config.apiUrl}`)
yield* Console.log(`Timeout: ${config.timeout}ms`)
return "data"
})
// Provide the service implementation
const program = Effect.provideService(fetchData, Config, {
apiUrl: "https://api.example.com",
timeout: 5000
})
Effect.runPromise(program).then(console.log)
// Output:
// Fetching from: https://api.example.com
// Timeout: 5000ms
// dataexport const const provideService: {
<I, S>(service: Context.Key<I, S>): {
(implementation: S): <A, E, R>(
self: Effect<A, E, R>
) => Effect<A, E, Exclude<R, I>>
<A, E, R>(
self: Effect<A, E, R>,
implementation: S
): Effect<A, E, Exclude<R, I>>
}
<I, S>(
service: Context.Key<I, S>,
implementation: S
): <A, E, R>(
self: Effect<A, E, R>
) => Effect<A, E, Exclude<R, I>>
<A, E, R, I, S>(
self: Effect<A, E, R>,
service: Context.Key<I, S>,
implementation: S
): Effect<A, E, Exclude<R, I>>
}
Provides one concrete service implementation to an effect.
When to use
Use to satisfy one service requirement with an already-built implementation.
Details
The service requirement identified by the Context.Key is removed from the
effect requirements after the implementation is provided.
Example (Providing a service value)
import { Console, Context, Effect } from "effect"
// Define a service for configuration
const Config = Context.Service<{
apiUrl: string
timeout: number
}>("Config")
const fetchData = Effect.gen(function*() {
const config = yield* Effect.service(Config)
yield* Console.log(`Fetching from: ${config.apiUrl}`)
yield* Console.log(`Timeout: ${config.timeout}ms`)
return "data"
})
// Provide the service implementation
const program = Effect.provideService(fetchData, Config, {
apiUrl: "https://api.example.com",
timeout: 5000
})
Effect.runPromise(program).then(console.log)
// Output:
// Fetching from: https://api.example.com
// Timeout: 5000ms
// data
provideService: {
<function (type parameter) I in <I, S>(service: Context.Key<I, S>): {
(implementation: S): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, I>>;
<A, E, R>(self: Effect<A, E, R>, implementation: S): Effect<A, E, Exclude<R, I>>;
}
function (type parameter) S in <I, S>(service: Context.Key<I, S>): {
(implementation: S): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, I>>;
<A, E, R>(self: Effect<A, E, R>, implementation: S): Effect<A, E, Exclude<R, I>>;
}
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.type Context.Key = /*unresolved*/ anyKey<function (type parameter) I in <I, S>(service: Context.Key<I, S>): {
(implementation: S): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, I>>;
<A, E, R>(self: Effect<A, E, R>, implementation: S): Effect<A, E, Exclude<R, I>>;
}
function (type parameter) S in <I, S>(service: Context.Key<I, S>): {
(implementation: S): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, I>>;
<A, E, R>(self: Effect<A, E, R>, implementation: S): Effect<A, E, Exclude<R, I>>;
}
implementation: Simplementation: function (type parameter) S in <I, S>(service: Context.Key<I, S>): {
(implementation: S): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, I>>;
<A, E, R>(self: Effect<A, E, R>, implementation: S): Effect<A, E, Exclude<R, I>>;
}
function (type parameter) A in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, I>>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, I>>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, I>>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, Exclude<R, I>>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, I>>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, I>>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, Exclude<R, I>>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, I>>E, 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, Exclude<R, I>>R, function (type parameter) I in <I, S>(service: Context.Key<I, S>): {
(implementation: S): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, I>>;
<A, E, R>(self: Effect<A, E, R>, implementation: S): Effect<A, E, Exclude<R, I>>;
}
function (type parameter) A in <A, E, R>(self: Effect<A, E, R>, implementation: S): Effect<A, E, Exclude<R, I>>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>, implementation: S): Effect<A, E, Exclude<R, I>>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>, implementation: S): Effect<A, E, Exclude<R, I>>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>, implementation: S): Effect<A, E, Exclude<R, I>>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>, implementation: S): Effect<A, E, Exclude<R, I>>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>, implementation: S): Effect<A, E, Exclude<R, I>>R>, implementation: Simplementation: function (type parameter) S in <I, S>(service: Context.Key<I, S>): {
(implementation: S): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, I>>;
<A, E, R>(self: Effect<A, E, R>, implementation: S): Effect<A, E, Exclude<R, I>>;
}
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>, implementation: S): Effect<A, E, Exclude<R, I>>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>, implementation: S): Effect<A, E, Exclude<R, I>>E, 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>, implementation: S): Effect<A, E, Exclude<R, I>>R, function (type parameter) I in <I, S>(service: Context.Key<I, S>): {
(implementation: S): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, I>>;
<A, E, R>(self: Effect<A, E, R>, implementation: S): Effect<A, E, Exclude<R, I>>;
}
function (type parameter) I in <I, S>(service: Context.Key<I, S>, implementation: S): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, I>>I, function (type parameter) S in <I, S>(service: Context.Key<I, S>, implementation: S): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, I>>S>(
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.type Context.Key = /*unresolved*/ anyKey<function (type parameter) I in <I, S>(service: Context.Key<I, S>, implementation: S): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, I>>I, function (type parameter) S in <I, S>(service: Context.Key<I, S>, implementation: S): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, I>>S>,
implementation: Simplementation: function (type parameter) S in <I, S>(service: Context.Key<I, S>, implementation: S): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, I>>S
): <function (type parameter) A in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, I>>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, I>>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, I>>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, Exclude<R, I>>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, I>>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, I>>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, Exclude<R, I>>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, I>>E, 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, Exclude<R, I>>R, function (type parameter) I in <I, S>(service: Context.Key<I, S>, implementation: S): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, I>>I>>
<function (type parameter) A in <A, E, R, I, S>(self: Effect<A, E, R>, service: Context.Key<I, S>, implementation: S): Effect<A, E, Exclude<R, I>>A, function (type parameter) E in <A, E, R, I, S>(self: Effect<A, E, R>, service: Context.Key<I, S>, implementation: S): Effect<A, E, Exclude<R, I>>E, function (type parameter) R in <A, E, R, I, S>(self: Effect<A, E, R>, service: Context.Key<I, S>, implementation: S): Effect<A, E, Exclude<R, I>>R, function (type parameter) I in <A, E, R, I, S>(self: Effect<A, E, R>, service: Context.Key<I, S>, implementation: S): Effect<A, E, Exclude<R, I>>I, function (type parameter) S in <A, E, R, I, S>(self: Effect<A, E, R>, service: Context.Key<I, S>, implementation: S): Effect<A, E, Exclude<R, I>>S>(
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>(self: Effect<A, E, R>, service: Context.Key<I, S>, implementation: S): Effect<A, E, Exclude<R, I>>A, function (type parameter) E in <A, E, R, I, S>(self: Effect<A, E, R>, service: Context.Key<I, S>, implementation: S): Effect<A, E, Exclude<R, I>>E, function (type parameter) R in <A, E, R, I, S>(self: Effect<A, E, R>, service: Context.Key<I, S>, implementation: S): Effect<A, E, Exclude<R, I>>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.type Context.Key = /*unresolved*/ anyKey<function (type parameter) I in <A, E, R, I, S>(self: Effect<A, E, R>, service: Context.Key<I, S>, implementation: S): Effect<A, E, Exclude<R, I>>I, function (type parameter) S in <A, E, R, I, S>(self: Effect<A, E, R>, service: Context.Key<I, S>, implementation: S): Effect<A, E, Exclude<R, I>>S>,
implementation: Simplementation: function (type parameter) S in <A, E, R, I, S>(self: Effect<A, E, R>, service: Context.Key<I, S>, implementation: S): Effect<A, E, Exclude<R, I>>S
): 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>(self: Effect<A, E, R>, service: Context.Key<I, S>, implementation: S): Effect<A, E, Exclude<R, I>>A, function (type parameter) E in <A, E, R, I, S>(self: Effect<A, E, R>, service: Context.Key<I, S>, implementation: S): Effect<A, E, Exclude<R, I>>E, 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>(self: Effect<A, E, R>, service: Context.Key<I, S>, implementation: S): Effect<A, E, Exclude<R, I>>R, function (type parameter) I in <A, E, R, I, S>(self: Effect<A, E, R>, service: Context.Key<I, S>, implementation: S): Effect<A, E, Exclude<R, I>>I>>
} = import internalinternal.const provideService: {
<I, S>(service: Context.Key<I, S>): {
(implementation: S): <A, E, R>(
self: Effect.Effect<A, E, R>
) => Effect.Effect<A, E, Exclude<R, I>>
<A, E, R>(
self: Effect.Effect<A, E, R>,
implementation: S
): Effect.Effect<A, E, Exclude<R, I>>
}
<I, S>(
key: Context.Key<I, S>,
implementation: S
): <A, E, R>(
self: Effect.Effect<A, E, R>
) => Effect.Effect<A, E, Exclude<R, I>>
<A, E, R, I, S>(
self: Effect.Effect<A, E, R>,
service: Context.Key<I, S>,
implementation: S
): Effect.Effect<A, E, Exclude<R, I>>
}