<XR>(context: Context.Context<XR>): <A, E, R>(
self: Effect<A, E, R>
) => Effect<A, E, Exclude<R, XR>>
<A, E, R, XR>(
self: Effect<A, E, R>,
context: Context.Context<XR>
): Effect<A, E, Exclude<R, XR>>Provides a context to an effect, fulfilling its service requirements.
Details
This function provides multiple services at once by supplying a context that contains all the required services. It removes the provided services from the effect's requirements, making them available to the effect.
Example (Providing a complete context)
import { Context, Effect } from "effect"
// Define service keys
const Logger = Context.Service<{
log: (msg: string) => void
}>("Logger")
const Database = Context.Service<{
query: (sql: string) => string
}>("Database")
// Create a context with multiple services
const context = Context.make(Logger, { log: console.log })
.pipe(Context.add(Database, { query: () => "result" }))
// An effect that requires both services
const program = Effect.gen(function*() {
const logger = yield* Effect.service(Logger)
const db = yield* Effect.service(Database)
logger.log("Querying database")
return db.query("SELECT * FROM users")
})
const provided = Effect.provideContext(program, context)export const const provideContext: {
<XR>(context: Context.Context<XR>): <A, E, R>(
self: Effect<A, E, R>
) => Effect<A, E, Exclude<R, XR>>
<A, E, R, XR>(
self: Effect<A, E, R>,
context: Context.Context<XR>
): Effect<A, E, Exclude<R, XR>>
}
Provides a context to an effect, fulfilling its service requirements.
Details
This function provides multiple services at once by supplying a context
that contains all the required services. It removes the provided services
from the effect's requirements, making them available to the effect.
Example (Providing a complete context)
import { Context, Effect } from "effect"
// Define service keys
const Logger = Context.Service<{
log: (msg: string) => void
}>("Logger")
const Database = Context.Service<{
query: (sql: string) => string
}>("Database")
// Create a context with multiple services
const context = Context.make(Logger, { log: console.log })
.pipe(Context.add(Database, { query: () => "result" }))
// An effect that requires both services
const program = Effect.gen(function*() {
const logger = yield* Effect.service(Logger)
const db = yield* Effect.service(Database)
logger.log("Querying database")
return db.query("SELECT * FROM users")
})
const provided = Effect.provideContext(program, context)
provideContext: {
<function (type parameter) XR in <XR>(context: Context.Context<XR>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, XR>>XR>(
context: Context.Context<XR>(parameter) context: {
mapUnsafe: ReadonlyMap<string, any>;
mutable: boolean;
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 Context<in Services>Immutable collection of service implementations used for dependency
injection in Effect programs.
Details
The type parameter tracks the service identifiers available in the context.
At runtime, services are stored by each key's string key.
Example (Creating a context with multiple services)
import { Context } from "effect"
// Create a context with multiple services
const Logger = Context.Service<{ log: (msg: string) => void }>("Logger")
const Database = Context.Service<{ query: (sql: string) => string }>(
"Database"
)
const context = Context.make(Logger, {
log: (msg: string) => console.log(msg)
})
.pipe(Context.add(Database, { query: (sql) => `Result: ${sql}` }))
Context<function (type parameter) XR in <XR>(context: Context.Context<XR>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, XR>>XR>
): <function (type parameter) A in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, XR>>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, XR>>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, XR>>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, XR>>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, XR>>E, function (type parameter) R in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, XR>>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, XR>>A, function (type parameter) E in <A, E, R>(self: Effect<A, E, R>): Effect<A, E, Exclude<R, XR>>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, XR>>R, function (type parameter) XR in <XR>(context: Context.Context<XR>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, XR>>XR>>
<function (type parameter) A in <A, E, R, XR>(self: Effect<A, E, R>, context: Context.Context<XR>): Effect<A, E, Exclude<R, XR>>A, function (type parameter) E in <A, E, R, XR>(self: Effect<A, E, R>, context: Context.Context<XR>): Effect<A, E, Exclude<R, XR>>E, function (type parameter) R in <A, E, R, XR>(self: Effect<A, E, R>, context: Context.Context<XR>): Effect<A, E, Exclude<R, XR>>R, function (type parameter) XR in <A, E, R, XR>(self: Effect<A, E, R>, context: Context.Context<XR>): Effect<A, E, Exclude<R, XR>>XR>(
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, XR>(self: Effect<A, E, R>, context: Context.Context<XR>): Effect<A, E, Exclude<R, XR>>A, function (type parameter) E in <A, E, R, XR>(self: Effect<A, E, R>, context: Context.Context<XR>): Effect<A, E, Exclude<R, XR>>E, function (type parameter) R in <A, E, R, XR>(self: Effect<A, E, R>, context: Context.Context<XR>): Effect<A, E, Exclude<R, XR>>R>,
context: Context.Context<XR>(parameter) context: {
mapUnsafe: ReadonlyMap<string, any>;
mutable: boolean;
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 Context<in Services>Immutable collection of service implementations used for dependency
injection in Effect programs.
Details
The type parameter tracks the service identifiers available in the context.
At runtime, services are stored by each key's string key.
Example (Creating a context with multiple services)
import { Context } from "effect"
// Create a context with multiple services
const Logger = Context.Service<{ log: (msg: string) => void }>("Logger")
const Database = Context.Service<{ query: (sql: string) => string }>(
"Database"
)
const context = Context.make(Logger, {
log: (msg: string) => console.log(msg)
})
.pipe(Context.add(Database, { query: (sql) => `Result: ${sql}` }))
Context<function (type parameter) XR in <A, E, R, XR>(self: Effect<A, E, R>, context: Context.Context<XR>): Effect<A, E, Exclude<R, XR>>XR>
): 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, XR>(self: Effect<A, E, R>, context: Context.Context<XR>): Effect<A, E, Exclude<R, XR>>A, function (type parameter) E in <A, E, R, XR>(self: Effect<A, E, R>, context: Context.Context<XR>): Effect<A, E, Exclude<R, XR>>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, XR>(self: Effect<A, E, R>, context: Context.Context<XR>): Effect<A, E, Exclude<R, XR>>R, function (type parameter) XR in <A, E, R, XR>(self: Effect<A, E, R>, context: Context.Context<XR>): Effect<A, E, Exclude<R, XR>>XR>>
} = import internalinternal.const provideContext: {
<XR>(context: Context.Context<XR>): <A, E, R>(
self: Effect.Effect<A, E, R>
) => Effect.Effect<A, E, Exclude<R, XR>>
<A, E, R, XR>(
self: Effect.Effect<A, E, R>,
context: Context.Context<XR>
): Effect.Effect<A, E, Exclude<R, XR>>
}