<R2>(context: Context.Context<R2>): <A, E, R>(
self: Stream<A, E, R>
) => Stream<A, E, Exclude<R, R2>>
<A, E, R, R2>(
self: Stream<A, E, R>,
context: Context.Context<R2>
): Stream<A, E, Exclude<R, R2>>Provides multiple services to the stream using a context.
Example (Providing multiple services to the stream using a context)
import { Console, Context, Effect, Stream } from "effect"
class Config extends Context.Service<Config, { readonly prefix: string }>()("Config") {}
class Greeter extends Context.Service<Greeter, { greet: (name: string) => string }>()("Greeter") {}
const context = Context.make(Config, { prefix: "Hello" }).pipe(
Context.add(Greeter, { greet: (name: string) => `${name}!` })
)
const stream = Stream.fromEffect(
Effect.gen(function*() {
const config = yield* Effect.service(Config)
const greeter = yield* Effect.service(Greeter)
return greeter.greet(config.prefix)
})
)
const program = Effect.gen(function*() {
const result = yield* Stream.runCollect(Stream.provideContext(stream, context))
yield* Console.log(result)
})
Effect.runPromise(program)
// ["Hello!"]services
Source effect/Stream.ts:100908 lines
export const const provideContext: {
<R2>(context: Context.Context<R2>): <A, E, R>(
self: Stream<A, E, R>
) => Stream<A, E, Exclude<R, R2>>
<A, E, R, R2>(
self: Stream<A, E, R>,
context: Context.Context<R2>
): Stream<A, E, Exclude<R, R2>>
}
Provides multiple services to the stream using a context.
Example (Providing multiple services to the stream using a context)
import { Console, Context, Effect, Stream } from "effect"
class Config extends Context.Service<Config, { readonly prefix: string }>()("Config") {}
class Greeter extends Context.Service<Greeter, { greet: (name: string) => string }>()("Greeter") {}
const context = Context.make(Config, { prefix: "Hello" }).pipe(
Context.add(Greeter, { greet: (name: string) => `${name}!` })
)
const stream = Stream.fromEffect(
Effect.gen(function*() {
const config = yield* Effect.service(Config)
const greeter = yield* Effect.service(Greeter)
return greeter.greet(config.prefix)
})
)
const program = Effect.gen(function*() {
const result = yield* Stream.runCollect(Stream.provideContext(stream, context))
yield* Console.log(result)
})
Effect.runPromise(program)
// ["Hello!"]
provideContext: {
<function (type parameter) R2 in <R2>(context: Context.Context<R2>): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E, Exclude<R, R2>>R2>(context: Context.Context<R2>(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) R2 in <R2>(context: Context.Context<R2>): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E, Exclude<R, R2>>R2>): <function (type parameter) A in <A, E, R>(self: Stream<A, E, R>): Stream<A, E, Exclude<R, R2>>A, function (type parameter) E in <A, E, R>(self: Stream<A, E, R>): Stream<A, E, Exclude<R, R2>>E, function (type parameter) R in <A, E, R>(self: Stream<A, E, R>): Stream<A, E, Exclude<R, R2>>R>(self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
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 Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R>(self: Stream<A, E, R>): Stream<A, E, Exclude<R, R2>>A, function (type parameter) E in <A, E, R>(self: Stream<A, E, R>): Stream<A, E, Exclude<R, R2>>E, function (type parameter) R in <A, E, R>(self: Stream<A, E, R>): Stream<A, E, Exclude<R, R2>>R>) => interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R>(self: Stream<A, E, R>): Stream<A, E, Exclude<R, R2>>A, function (type parameter) E in <A, E, R>(self: Stream<A, E, R>): Stream<A, E, Exclude<R, R2>>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: Stream<A, E, R>): Stream<A, E, Exclude<R, R2>>R, function (type parameter) R2 in <R2>(context: Context.Context<R2>): <A, E, R>(self: Stream<A, E, R>) => Stream<A, E, Exclude<R, R2>>R2>>
<function (type parameter) A in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>A, function (type parameter) E in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>E, function (type parameter) R in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>R, function (type parameter) R2 in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>R2>(self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
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 Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>A, function (type parameter) E in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>E, function (type parameter) R in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>R>, context: Context.Context<R2>(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) R2 in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>R2>): interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>A, function (type parameter) E in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>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, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>R, function (type parameter) R2 in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>R2>>
} = dual<(...args: Array<any>) => any, <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>) => Stream<A, E, Exclude<R, R2>>>(arity: 2, body: <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>) => Stream<A, E, Exclude<R, R2>>): ((...args: Array<any>) => any) & (<A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>) => Stream<A, E, Exclude<R, R2>>) (+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, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>A, function (type parameter) E in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>E, function (type parameter) R in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>R, function (type parameter) R2 in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>R2>(self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
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 Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>A, function (type parameter) E in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>E, function (type parameter) R in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>R>, context: Context.Context<R2>(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) R2 in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>R2>): interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>A, function (type parameter) E in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>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, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>R, function (type parameter) R2 in <A, E, R, R2>(self: Stream<A, E, R>, context: Context.Context<R2>): Stream<A, E, Exclude<R, R2>>R2>> =>
const fromChannel: <
Arr extends Arr.NonEmptyReadonlyArray<any>,
E,
R
>(
channel: Channel.Channel<
Arr,
E,
void,
unknown,
unknown,
unknown,
R
>
) => Stream<
Arr extends Arr.NonEmptyReadonlyArray<infer A>
? A
: never,
E,
R
>
Creates a stream from a array-emitting Channel.
Example (Creating a stream from an array-emitting channel)
import { Channel, Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const channel = Channel.succeed([1, 2, 3] as const)
const stream = Stream.fromChannel(channel)
const result = yield* Stream.runCollect(stream)
yield* Console.log(result)
})
// Output: [ 1, 2, 3 ]
fromChannel(import ChannelChannel.const provideContext: {
<R2>(context: Context.Context<R2>): <
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Exclude<Env, R2>
>
<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env,
R2
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
context: Context.Context<R2>
): Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Exclude<Env, R2>
>
}
self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
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; <…;
}
Stream<A, E, R>.channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>(property) Stream<A, E, R>.channel: {
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; <…;
}
context: Context.Context<R2>(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;
}