<OutElem, OutErr, OutDone, Env>(
self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>
): Effect.Effect<OutDone, OutErr, Env>Runs a channel and discards all output elements, returning only the final result.
Example (Draining channel output at runtime)
import { Channel, Data } from "effect"
class DrainError extends Data.TaggedError("DrainError")<{
readonly stage: string
}> {}
// Create a channel that outputs elements and completes with a result
const resultChannel = Channel.fromIterable([1, 2, 3])
const completedChannel = Channel.concatWith(
resultChannel,
() => Channel.succeed("completed")
)
// Drain all elements and get only the final result
const drainEffect = Channel.runDrain(completedChannel)
// Effect.runSync(drainEffect) // Returns: "completed"execution
Source effect/Channel.ts:77243 lines
export const const runDrain: <
OutElem,
OutErr,
OutDone,
Env
>(
self: Channel<
OutElem,
OutErr,
OutDone,
unknown,
unknown,
unknown,
Env
>
) => Effect.Effect<OutDone, OutErr, Env>
Runs a channel and discards all output elements, returning only the final result.
Example (Draining channel output at runtime)
import { Channel, Data } from "effect"
class DrainError extends Data.TaggedError("DrainError")<{
readonly stage: string
}> {}
// Create a channel that outputs elements and completes with a result
const resultChannel = Channel.fromIterable([1, 2, 3])
const completedChannel = Channel.concatWith(
resultChannel,
() => Channel.succeed("completed")
)
// Drain all elements and get only the final result
const drainEffect = Channel.runDrain(completedChannel)
// Effect.runSync(drainEffect) // Returns: "completed"
runDrain = <function (type parameter) OutElem in <OutElem, OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr, Env>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr, Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr, Env>OutDone, function (type parameter) Env in <OutElem, OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr, Env>Env>(
self: Channel<
OutElem,
OutErr,
OutDone,
unknown,
unknown,
unknown,
Env
>
(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; <…;
}
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) OutElem in <OutElem, OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr, Env>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr, Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr, Env>OutDone, unknown, unknown, unknown, function (type parameter) Env in <OutElem, OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr, Env>Env>
): 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<function (type parameter) OutDone in <OutElem, OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr, Env>OutDone, function (type parameter) OutErr in <OutElem, OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr, Env>OutErr, function (type parameter) Env in <OutElem, OutErr, OutDone, Env>(self: Channel<OutElem, OutErr, OutDone, unknown, unknown, unknown, Env>): Effect.Effect<OutDone, OutErr, Env>Env> => const runWith: <
OutElem,
OutErr,
OutDone,
Env,
EX,
RX,
AH = OutDone,
EH = never,
RH = never
>(
self: Channel<
OutElem,
OutErr,
OutDone,
unknown,
unknown,
unknown,
Env
>,
f: (
pull: Pull.Pull<OutElem, OutErr, OutDone>
) => Effect.Effect<void, EX, RX>,
onHalt?: (
leftover: OutDone
) => Effect.Effect<AH, EH, RH>
) => Effect.Effect<
AH,
Pull.ExcludeDone<EX> | EH,
Env | RX | RH
>
self: Channel<
OutElem,
OutErr,
OutDone,
unknown,
unknown,
unknown,
Env
>
(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; <…;
}
pull: Pull.Pull<
OutElem,
OutErr,
OutDone,
never
>
(parameter) pull: {
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 EffectEffect.const forever: <
Arg extends
| Effect<any, any, any>
| {
readonly disableYield?:
| boolean
| undefined
}
| undefined = {
readonly disableYield?: boolean | undefined
}
>(
effectOrOptions?: Arg,
options?:
| {
readonly disableYield?:
| boolean
| undefined
}
| undefined
) => [Arg] extends [
Effect<infer _A, infer _E, infer _R>
]
? Effect<never, _E, _R>
: <A, E, R>(
self: Effect<A, E, R>
) => Effect<never, E, R>
Repeats this effect forever (until the first error).
Example (Repeating forever)
import { Console, Effect, Fiber } from "effect"
const task = Effect.gen(function*() {
yield* Console.log("Task running...")
yield* Effect.sleep("1 second")
})
// This will run forever, printing every second
const program = task.pipe(Effect.forever)
// This will run forever, without yielding every iteration
const programNoYield = task.pipe(Effect.forever({ disableYield: true }))
// Run for 5 seconds then interrupt
const timedProgram = Effect.gen(function*() {
const fiber = yield* Effect.forkChild(program)
yield* Effect.sleep("5 seconds")
yield* Fiber.interrupt(fiber)
})
forever(pull: Pull.Pull<
OutElem,
OutErr,
OutDone,
never
>
(parameter) pull: {
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;
}
disableYield?: boolean | undefineddisableYield: true }))Referenced by 1 symbols