<A, E = never, R = never>(
f: (
queue: Queue.Queue<A, E | Cause.Done>
) => Effect.Effect<unknown, E, R | Scope.Scope>,
options?: {
readonly bufferSize?: number | undefined
readonly strategy?: "sliding" | "dropping" | "suspend" | undefined
}
): Channel<A, E, void, unknown, unknown, unknown, Exclude<R, Scope.Scope>>Creates a Channel that interacts with a callback function using a queue.
Example (Creating channels from callbacks)
import { Channel, Effect, Queue } from "effect"
const channel = Channel.callback<number>((queue) =>
Effect.gen(function*() {
yield* Queue.offer(queue, 1)
yield* Queue.offer(queue, 2)
yield* Queue.offer(queue, 3)
})
)constructors
Source effect/Channel.ts:4838 lines
export const const callback: <A, E = never, R = never>(
f: (
queue: Queue.Queue<A, E | Cause.Done>
) => Effect.Effect<unknown, E, R | Scope.Scope>,
options?: {
readonly bufferSize?: number | undefined
readonly strategy?:
| "sliding"
| "dropping"
| "suspend"
| undefined
}
) => Channel<
A,
E,
void,
unknown,
unknown,
unknown,
Exclude<R, Scope.Scope>
>
Creates a Channel that interacts with a callback function using a queue.
Example (Creating channels from callbacks)
import { Channel, Effect, Queue } from "effect"
const channel = Channel.callback<number>((queue) =>
Effect.gen(function*() {
yield* Queue.offer(queue, 1)
yield* Queue.offer(queue, 2)
yield* Queue.offer(queue, 3)
})
)
callback = <function (type parameter) A in <A, E = never, R = never>(f: (queue: Queue.Queue<A, E | Cause.Done>) => Effect.Effect<unknown, E, R | Scope.Scope>, options?: {
readonly bufferSize?: number | undefined;
readonly strategy?: "sliding" | "dropping" | "suspend" | undefined;
}): Channel<A, E, void, unknown, unknown, unknown, Exclude<R, Scope.Scope>>
function (type parameter) E in <A, E = never, R = never>(f: (queue: Queue.Queue<A, E | Cause.Done>) => Effect.Effect<unknown, E, R | Scope.Scope>, options?: {
readonly bufferSize?: number | undefined;
readonly strategy?: "sliding" | "dropping" | "suspend" | undefined;
}): Channel<A, E, void, unknown, unknown, unknown, Exclude<R, Scope.Scope>>
function (type parameter) R in <A, E = never, R = never>(f: (queue: Queue.Queue<A, E | Cause.Done>) => Effect.Effect<unknown, E, R | Scope.Scope>, options?: {
readonly bufferSize?: number | undefined;
readonly strategy?: "sliding" | "dropping" | "suspend" | undefined;
}): Channel<A, E, void, unknown, unknown, unknown, Exclude<R, Scope.Scope>>
f: (
queue: Queue.Queue<A, E | Cause.Done>
) => Effect.Effect<unknown, E, R | Scope.Scope>
queue: Queue.Queue<A, E | Cause.Done>(parameter) queue: {
strategy: "suspend" | "dropping" | "sliding";
dispatcher: SchedulerDispatcher;
capacity: number;
messages: MutableList.MutableList<any>;
state: Queue.State<any, any>;
scheduleRunning: boolean;
toString: () => string;
toJSON: () => unknown;
}
import QueueQueue.interface Queue<in out A, in out E = never>A Queue is an asynchronous queue that can be offered to and taken from.
Details
It also supports signaling that it is done or failed.
Example (Offering and taking queue values)
import { Effect, Queue } from "effect"
const program = Effect.gen(function*() {
// Create a bounded queue
const queue = yield* Queue.bounded<string>(10)
// Producer: offer items to the queue
yield* Queue.offer(queue, "hello")
yield* Queue.offerAll(queue, ["world", "!"])
// Consumer: take items from the queue
const item1 = yield* Queue.take(queue)
const item2 = yield* Queue.take(queue)
const item3 = yield* Queue.take(queue)
console.log([item1, item2, item3]) // ["hello", "world", "!"]
})
Companion namespace containing type-level metadata and low-level state types
for Queue.
Queue<function (type parameter) A in <A, E = never, R = never>(f: (queue: Queue.Queue<A, E | Cause.Done>) => Effect.Effect<unknown, E, R | Scope.Scope>, options?: {
readonly bufferSize?: number | undefined;
readonly strategy?: "sliding" | "dropping" | "suspend" | undefined;
}): Channel<A, E, void, unknown, unknown, unknown, Exclude<R, Scope.Scope>>
function (type parameter) E in <A, E = never, R = never>(f: (queue: Queue.Queue<A, E | Cause.Done>) => Effect.Effect<unknown, E, R | Scope.Scope>, options?: {
readonly bufferSize?: number | undefined;
readonly strategy?: "sliding" | "dropping" | "suspend" | undefined;
}): Channel<A, E, void, unknown, unknown, unknown, Exclude<R, Scope.Scope>>
import CauseCause.type Cause.Done = /*unresolved*/ anyDone>) => 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<unknown, function (type parameter) E in <A, E = never, R = never>(f: (queue: Queue.Queue<A, E | Cause.Done>) => Effect.Effect<unknown, E, R | Scope.Scope>, options?: {
readonly bufferSize?: number | undefined;
readonly strategy?: "sliding" | "dropping" | "suspend" | undefined;
}): Channel<A, E, void, unknown, unknown, unknown, Exclude<R, Scope.Scope>>
function (type parameter) R in <A, E = never, R = never>(f: (queue: Queue.Queue<A, E | Cause.Done>) => Effect.Effect<unknown, E, R | Scope.Scope>, options?: {
readonly bufferSize?: number | undefined;
readonly strategy?: "sliding" | "dropping" | "suspend" | undefined;
}): Channel<A, E, void, unknown, unknown, unknown, Exclude<R, Scope.Scope>>
import ScopeScope.Scope>,
options: | {
readonly bufferSize?: number | undefined
readonly strategy?:
| "sliding"
| "dropping"
| "suspend"
| undefined
}
| undefined
bufferSize?: number | undefinedbufferSize?: number | undefined
readonly strategy?: | "sliding"
| "dropping"
| "suspend"
| undefined
interface Channel<out OutElem, out OutErr = never, out OutDone = void, in InElem = unknown, in InErr = unknown, in InDone = unknown, out Env = never>A Channel is a nexus of I/O operations, which supports both reading and
writing. A channel may read values of type InElem and write values of type
OutElem. When the channel finishes, it yields a value of type OutDone. A
channel may fail with a value of type OutErr.
Details
Channels are the foundation of Streams: both streams and sinks are built on
channels. Most users shouldn't have to use channels directly, as streams and
sinks are much more convenient and cover all common use cases. However, when
adding new stream and sink operators, or doing something highly specialized,
it may be useful to use channels directly.
Channels compose in a variety of ways:
- Piping: One channel can be piped to another channel, assuming the
input type of the second is the same as the output type of the first.
- Sequencing: The terminal value of one channel can be used to create
another channel, and both the first channel and the function that makes
the second channel can be composed into a channel.
- Concatenating: The output of one channel can be used to create other
channels, which are all concatenated together. The first channel and the
function that makes the other channels can be composed into a channel.
Example (Typing channels)
import type { Channel } from "effect"
// A channel that outputs numbers and requires no environment
type NumberChannel = Channel.Channel<number>
// A channel that outputs strings, can fail with Error, completes with boolean
type StringChannel = Channel.Channel<string, Error, boolean>
// A channel with all type parameters specified
type FullChannel = Channel.Channel<
string, // OutElem - output elements
Error, // OutErr - output errors
number, // OutDone - completion value
number, // InElem - input elements
string, // InErr - input errors
boolean, // InDone - input completion
{ db: string } // Env - required environment
>
Channel<function (type parameter) A in <A, E = never, R = never>(f: (queue: Queue.Queue<A, E | Cause.Done>) => Effect.Effect<unknown, E, R | Scope.Scope>, options?: {
readonly bufferSize?: number | undefined;
readonly strategy?: "sliding" | "dropping" | "suspend" | undefined;
}): Channel<A, E, void, unknown, unknown, unknown, Exclude<R, Scope.Scope>>
function (type parameter) E in <A, E = never, R = never>(f: (queue: Queue.Queue<A, E | Cause.Done>) => Effect.Effect<unknown, E, R | Scope.Scope>, options?: {
readonly bufferSize?: number | undefined;
readonly strategy?: "sliding" | "dropping" | "suspend" | undefined;
}): Channel<A, E, void, unknown, unknown, unknown, Exclude<R, Scope.Scope>>
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 = never, R = never>(f: (queue: Queue.Queue<A, E | Cause.Done>) => Effect.Effect<unknown, E, R | Scope.Scope>, options?: {
readonly bufferSize?: number | undefined;
readonly strategy?: "sliding" | "dropping" | "suspend" | undefined;
}): Channel<A, E, void, unknown, unknown, unknown, Exclude<R, Scope.Scope>>
import ScopeScope.Scope>> =>
const fromTransform: <
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
EX,
EnvX,
Env
>(
transform: (
upstream: Pull.Pull<InElem, InErr, InDone>,
scope: Scope.Scope
) => Effect.Effect<
Pull.Pull<OutElem, OutErr, OutDone, EnvX>,
EX,
Env
>
) => Channel<
OutElem,
Pull.ExcludeDone<OutErr> | EX,
OutDone,
InElem,
InErr,
InDone,
Env | EnvX
>
Creates a Channel from a transformation function that operates on upstream pulls.
Example (Creating channels from transforms)
import { Channel, Effect } from "effect"
const channel = Channel.fromTransform((upstream, scope) =>
Effect.succeed(upstream)
)
fromTransform((_: Pull.Pull<
unknown,
unknown,
unknown,
never
>
(parameter) _: {
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;
}
scope: Scope.Scope(parameter) scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
import EffectEffect.const map: {
<A, B>(f: (a: A) => B): <E, R>(
self: Effect<A, E, R>
) => Effect<B, E, R>
<A, E, R, B>(
self: Effect<A, E, R>,
f: (a: A) => B
): Effect<B, E, R>
}
const asyncQueue: <
A,
E = never,
R = never
>(
scope: Scope.Scope,
f: (
queue: Queue.Queue<A, E | Cause.Done>
) => Effect.Effect<unknown, E, R | Scope.Scope>,
options?: {
readonly bufferSize?: number | undefined
readonly strategy?:
| "sliding"
| "dropping"
| "suspend"
| undefined
}
) => Effect.Effect<
Queue.Queue<A, Cause.Done<void> | E>,
never,
Exclude<R, Scope.Scope>
>
scope: Scope.Scope(parameter) scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
f: (
queue: Queue.Queue<A, E | Cause.Done>
) => Effect.Effect<unknown, E, R | Scope.Scope>
options: | {
readonly bufferSize?: number | undefined
readonly strategy?:
| "sliding"
| "dropping"
| "suspend"
| undefined
}
| undefined
import QueueQueue.const take: <A, E>(
self: Dequeue<A, E>
) => Effect<A, E>
Takes a single message from the queue, or wait for a message to be
available.
Details
If the queue is done, it will fail with Done. If the
queue fails, the Effect will fail with the error.
Example (Taking one value)
import { Cause, Effect, Queue } from "effect"
const program = Effect.gen(function*() {
const queue = yield* Queue.bounded<string, Cause.Done>(3)
// Add some messages
yield* Queue.offer(queue, "first")
yield* Queue.offer(queue, "second")
// Take messages one by one
const msg1 = yield* Queue.take(queue)
const msg2 = yield* Queue.take(queue)
console.log(msg1, msg2) // "first", "second"
// End the queue
yield* Queue.end(queue)
// Taking from an ended queue fails with Done
const result = yield* Effect.match(Queue.take(queue), {
onFailure: (error: Cause.Done) => true,
onSuccess: (value: string) => false
})
console.log("Queue ended:", result) // true
})
take))