<OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(
f: (
d: Cause.Cause<OutErr>
) => Channel<
OutElem1,
OutErr1,
OutDone1,
InElem1,
InErr1,
InDone1,
Env1
>
): <OutElem, OutDone, InElem, InErr, InDone, Env>(
self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>
) => Channel<
OutElem | OutElem1,
OutErr1,
OutDone | OutDone1,
InElem & InElem1,
InErr & InErr1,
InDone & InDone1,
Env | Env1
>
<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env,
OutElem1,
OutErr1,
OutDone1,
InElem1,
InErr1,
InDone1,
Env1
>(
self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>,
f: (
d: Cause.Cause<OutErr>
) => Channel<
OutElem1,
OutErr1,
OutDone1,
InElem1,
InErr1,
InDone1,
Env1
>
): Channel<
OutElem | OutElem1,
OutErr1,
OutDone | OutDone1,
InElem & InElem1,
InErr & InErr1,
InDone & InDone1,
Env | Env1
>Catches any cause of failure from the channel and allows recovery by creating a new channel based on the caught cause.
Example (Recovering from failure causes)
import { Cause, Channel, Data } from "effect"
class ProcessError extends Data.TaggedError("ProcessError")<{
readonly reason: string
}> {}
class RecoveryError extends Data.TaggedError("RecoveryError")<{
readonly message: string
}> {}
// Create a failing channel
const failingChannel = Channel.fail(
new ProcessError({ reason: "network error" })
)
// Catch the cause and provide recovery
const recoveredChannel = Channel.catchCause(failingChannel, (cause) => {
if (Cause.hasFails(cause)) {
return Channel.succeed("Recovered from failure")
}
return Channel.succeed("Recovered from interruption")
})
// The channel recovers gracefully from errorserror handling
Source effect/Channel.ts:388595 lines
export const const catchCause: {
<
OutErr,
OutElem1,
OutErr1,
OutDone1,
InElem1,
InErr1,
InDone1,
Env1
>(
f: (
d: Cause.Cause<OutErr>
) => Channel<
OutElem1,
OutErr1,
OutDone1,
InElem1,
InErr1,
InDone1,
Env1
>
): <
OutElem,
OutDone,
InElem,
InErr,
InDone,
Env
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => Channel<
OutElem | OutElem1,
OutErr1,
OutDone | OutDone1,
InElem & InElem1,
InErr & InErr1,
InDone & InDone1,
Env | Env1
>
<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env,
OutElem1,
OutErr1,
OutDone1,
InElem1,
InErr1,
InDone1,
Env1
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
f: (
d: Cause.Cause<OutErr>
) => Channel<
OutElem1,
OutErr1,
OutDone1,
InElem1,
InErr1,
InDone1,
Env1
>
): Channel<
OutElem | OutElem1,
OutErr1,
OutDone | OutDone1,
InElem & InElem1,
InErr & InErr1,
InDone & InDone1,
Env | Env1
>
}
Catches any cause of failure from the channel and allows recovery by
creating a new channel based on the caught cause.
Example (Recovering from failure causes)
import { Cause, Channel, Data } from "effect"
class ProcessError extends Data.TaggedError("ProcessError")<{
readonly reason: string
}> {}
class RecoveryError extends Data.TaggedError("RecoveryError")<{
readonly message: string
}> {}
// Create a failing channel
const failingChannel = Channel.fail(
new ProcessError({ reason: "network error" })
)
// Catch the cause and provide recovery
const recoveredChannel = Channel.catchCause(failingChannel, (cause) => {
if (Cause.hasFails(cause)) {
return Channel.succeed("Recovered from failure")
}
return Channel.succeed("Recovered from interruption")
})
// The channel recovers gracefully from errors
catchCause: {
<function (type parameter) OutErr in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr, function (type parameter) OutElem1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem1, function (type parameter) OutErr1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr1, function (type parameter) OutDone1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone1, function (type parameter) InElem1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem1, function (type parameter) InErr1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr1, function (type parameter) InDone1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone1, function (type parameter) Env1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env1>(
f: (
d: Cause.Cause<OutErr>
) => Channel<
OutElem1,
OutErr1,
OutDone1,
InElem1,
InErr1,
InDone1,
Env1
>
d: Cause.Cause<OutErr>(parameter) d: {
reasons: ReadonlyArray<Reason<E>>;
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 CauseCause.type Cause.Cause = /*unresolved*/ anyCause<function (type parameter) OutErr in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr>) => 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) OutElem1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem1, function (type parameter) OutErr1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr1, function (type parameter) OutDone1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone1, function (type parameter) InElem1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem1, function (type parameter) InErr1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr1, function (type parameter) InDone1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone1, function (type parameter) Env1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env1>
): <
function (type parameter) OutElem in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem,
function (type parameter) OutDone in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone,
function (type parameter) InElem in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem,
function (type parameter) InErr in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr,
function (type parameter) InDone in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone,
function (type parameter) Env in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env
>(self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
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, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem, function (type parameter) OutErr in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr, function (type parameter) OutDone in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone, function (type parameter) InElem in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem, function (type parameter) InErr in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr, function (type parameter) InDone in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone, function (type parameter) Env in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env>) => 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, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem | function (type parameter) OutElem1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem1,
function (type parameter) OutErr1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr1,
function (type parameter) OutDone in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone | function (type parameter) OutDone1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone1,
function (type parameter) InElem in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem & function (type parameter) InElem1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem1,
function (type parameter) InErr in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr & function (type parameter) InErr1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr1,
function (type parameter) InDone in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone & function (type parameter) InDone1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone1,
function (type parameter) Env in <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env | function (type parameter) Env1 in <OutErr, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): <OutElem, OutDone, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env1
>
<
function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem,
function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr,
function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone,
function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem,
function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr,
function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone,
function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env,
function (type parameter) OutElem1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem1,
function (type parameter) OutErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr1,
function (type parameter) OutDone1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone1,
function (type parameter) InElem1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem1,
function (type parameter) InErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr1,
function (type parameter) InDone1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone1,
function (type parameter) Env1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env1
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
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, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env>,
f: (
d: Cause.Cause<OutErr>
) => Channel<
OutElem1,
OutErr1,
OutDone1,
InElem1,
InErr1,
InDone1,
Env1
>
d: Cause.Cause<OutErr>(parameter) d: {
reasons: ReadonlyArray<Reason<E>>;
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 CauseCause.type Cause.Cause = /*unresolved*/ anyCause<function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr>) => 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) OutElem1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem1, function (type parameter) OutErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr1, function (type parameter) OutDone1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone1, function (type parameter) InElem1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem1, function (type parameter) InErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr1, function (type parameter) InDone1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone1, function (type parameter) Env1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env1>
): 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, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem | function (type parameter) OutElem1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem1,
function (type parameter) OutErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr1,
function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone | function (type parameter) OutDone1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone1,
function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem & function (type parameter) InElem1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem1,
function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr & function (type parameter) InErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr1,
function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone & function (type parameter) InDone1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone1,
function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env | function (type parameter) Env1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env1
>
} = dual<(...args: Array<any>) => any, <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>>(arity: 2, body: <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>): ((...args: Array<any>) => any) & (<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>) => Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>) (+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) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem,
function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr,
function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone,
function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem,
function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr,
function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone,
function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env,
function (type parameter) OutElem1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem1,
function (type parameter) OutErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr1,
function (type parameter) OutDone1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone1,
function (type parameter) InElem1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem1,
function (type parameter) InErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr1,
function (type parameter) InDone1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone1,
function (type parameter) Env1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env1
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
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, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env>,
f: (
d: Cause.Cause<OutErr>
) => Channel<
OutElem1,
OutErr1,
OutDone1,
InElem1,
InErr1,
InDone1,
Env1
>
d: Cause.Cause<OutErr>(parameter) d: {
reasons: ReadonlyArray<Reason<E>>;
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 CauseCause.type Cause.Cause = /*unresolved*/ anyCause<function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr>) => 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) OutElem1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem1, function (type parameter) OutErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr1, function (type parameter) OutDone1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone1, function (type parameter) InElem1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem1, function (type parameter) InErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr1, function (type parameter) InDone1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone1, function (type parameter) Env1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env1>
): 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, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem | function (type parameter) OutElem1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem1,
function (type parameter) OutErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr1,
function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone | function (type parameter) OutDone1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone1,
function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem & function (type parameter) InElem1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InElem1,
function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr & function (type parameter) InErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InErr1,
function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone & function (type parameter) InDone1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>InDone1,
function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env | function (type parameter) Env1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env1
> =>
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((upstream: Pull.Pull<
InElem & InElem1,
InErr & InErr1,
InDone & InDone1,
never
>
(parameter) upstream: {
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;
}
let forkedScope: Scope.Closeablelet forkedScope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
import ScopeScope.const forkUnsafe: (
scope: Scope,
finalizerStrategy?: "sequential" | "parallel"
) => Closeable
Creates a closeable child scope synchronously and registers it with a parent scope.
When to use
Use when a child scope must be created synchronously and the caller controls
both parent and child scope lifetimes.
Details
Closing the parent closes the child with the same exit value, and closing the
child detaches it from the parent. The optional finalizer strategy configures
the child scope and defaults to "sequential" when omitted.
Example (Creating a child scope synchronously)
import { Console, Effect, Exit, Scope } from "effect"
const program = Effect.gen(function*() {
const parentScope = Scope.makeUnsafe("sequential")
const childScope = Scope.forkUnsafe(parentScope, "parallel")
// Add finalizers to both scopes
yield* Scope.addFinalizer(parentScope, Console.log("Parent cleanup"))
yield* Scope.addFinalizer(childScope, Console.log("Child cleanup"))
// Close child first, then parent
yield* Scope.close(childScope, Exit.void)
yield* Scope.close(parentScope, Exit.void)
})
forkUnsafe(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 toTransform: <
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>(
channel: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => (
upstream: Pull.Pull<InElem, InErr, InDone>,
scope: Scope.Scope
) => Effect.Effect<
Pull.Pull<OutElem, OutErr, OutDone>,
never,
Env
>
Converts a Channel back to its underlying transformation function.
Example (Extracting channel transforms)
import { Channel } from "effect"
const channel = Channel.succeed(42)
const transform = Channel.toTransform(channel)
// transform can now be used directly
toTransform(self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
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; <…;
}
upstream: Pull.Pull<
InElem & InElem1,
InErr & InErr1,
InDone & InDone1,
never
>
(parameter) upstream: {
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;
}
let forkedScope: Scope.Closeablelet forkedScope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
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;
}
let currentPull: Pull.Pull<
OutElem | OutElem1,
OutErr1,
OutDone | OutDone1,
Env | Env1
>
let currentPull: {
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 PullPull.interface Pull<out A, out E = never, out Done = void, out R = never>An effectful pull step that either produces a value, fails with E, or
signals completion with Cause.Done<Done>.
When to use
Use to model one low-level pull step when a consumer repeatedly evaluates an
effect that may emit a value, fail normally, or signal normal completion
through Cause.Done.
Details
Pull represents completion in the error channel so low-level stream
consumers can distinguish ordinary failures from end-of-input and carry a
leftover value when needed.
Pull<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem | function (type parameter) OutElem1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem1, function (type parameter) OutErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr1, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone | function (type parameter) OutDone1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone1, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env | function (type parameter) Env1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env1> = 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;
}
Pipeable.pipe<Pull.Pull<OutElem, OutErr, OutDone, never>, Effect.Effect<OutElem | OutElem1, any, Env1>>(this: Pull.Pull<OutElem, OutErr, OutDone, never>, ab: (_: Pull.Pull<OutElem, OutErr, OutDone, never>) => Effect.Effect<OutElem | OutElem1, any, Env1>): Effect.Effect<OutElem | OutElem1, any, Env1> (+21 overloads)pipe(
import EffectEffect.const catchCause: {
<E, A2, E2, R2>(
f: (
cause: Cause.Cause<E>
) => Effect<A2, E2, R2>
): <A, R>(
self: Effect<A, E, R>
) => Effect<A2 | A, E2, R2 | R>
<A, E, R, A2, E2, R2>(
self: Effect<A, E, R>,
f: (
cause: Cause.Cause<E>
) => Effect<A2, E2, R2>
): Effect<A | A2, E2, R | R2>
}
cause: Cause.Cause<
OutErr | Cause.Done<OutDone>
>
(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
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 PullPull.interface Pull<out A, out E = never, out Done = void, out R = never>An effectful pull step that either produces a value, fails with E, or
signals completion with Cause.Done<Done>.
When to use
Use to model one low-level pull step when a consumer repeatedly evaluates an
effect that may emit a value, fail normally, or signal normal completion
through Cause.Done.
Details
Pull represents completion in the error channel so low-level stream
consumers can distinguish ordinary failures from end-of-input and carry a
leftover value when needed.
Pull<function (type parameter) OutElem1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutElem1, function (type parameter) OutErr1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr1, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone | function (type parameter) OutDone1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone1, function (type parameter) Env1 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>Env1> => {
if (import PullPull.const isDoneCause: <E>(
cause: Cause.Cause<E>
) => boolean
Checks whether a Cause contains any done errors.
When to use
Use when you need to test whether a pull failure cause represents normal
completion and only need a boolean result.
isDoneCause(cause: Cause.Cause<
OutErr | Cause.Done<OutDone>
>
(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
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 failCause: <E>(
cause: Cause.Cause<E>
) => Effect<never, E>
Creates an Effect that represents a failure with a specific Cause.
When to use
Use when you already have a full Cause and need to preserve defects,
interruptions, annotations, or combined failures in the effect's failure
channel.
Details
This function allows you to create effects that fail with complex error
structures, including multiple errors, defects, interruptions, and more.
Example (Failing with a full Cause)
import { Cause, Effect } from "effect"
const program = Effect.failCause(
Cause.fail("Network error")
)
Effect.runPromiseExit(program).then(console.log)
// Output: { _id: 'Exit', _tag: 'Failure', cause: ... }
failCause(cause: Cause.Cause<
OutErr | Cause.Done<OutDone>
>
(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
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 CauseCause.type Cause.Cause = /*unresolved*/ anyCause<import CauseCause.type Cause.Done = /*unresolved*/ anyDone<function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutDone>>)
}
const const toClose: Scope.Closeableconst toClose: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
let forkedScope: Scope.Closeablelet forkedScope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
let forkedScope: Scope.Closeablelet forkedScope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
import ScopeScope.const forkUnsafe: (
scope: Scope,
finalizerStrategy?: "sequential" | "parallel"
) => Closeable
Creates a closeable child scope synchronously and registers it with a parent scope.
When to use
Use when a child scope must be created synchronously and the caller controls
both parent and child scope lifetimes.
Details
Closing the parent closes the child with the same exit value, and closing the
child detaches it from the parent. The optional finalizer strategy configures
the child scope and defaults to "sequential" when omitted.
Example (Creating a child scope synchronously)
import { Console, Effect, Exit, Scope } from "effect"
const program = Effect.gen(function*() {
const parentScope = Scope.makeUnsafe("sequential")
const childScope = Scope.forkUnsafe(parentScope, "parallel")
// Add finalizers to both scopes
yield* Scope.addFinalizer(parentScope, Console.log("Parent cleanup"))
yield* Scope.addFinalizer(childScope, Console.log("Child cleanup"))
// Close child first, then parent
yield* Scope.close(childScope, Exit.void)
yield* Scope.close(parentScope, Exit.void)
})
forkUnsafe(scope: Scope.Scope(parameter) scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
import ScopeScope.const close: <A, E>(
self: Scope,
exit: Exit<A, E>
) => Effect<void>
Closes a scope and runs its registered finalizers.
When to use
Use to close a scope manually with a specific exit value.
Details
Finalizers run in the scope's configured order and receive the supplied
Exit.
Example (Running scope finalizers)
import { Console, Effect, Exit, Scope } from "effect"
const resourceManagement = Effect.gen(function*() {
const scope = yield* Scope.make("sequential")
// Add multiple finalizers
yield* Scope.addFinalizer(scope, Console.log("Close database connection"))
yield* Scope.addFinalizer(scope, Console.log("Close file handle"))
yield* Scope.addFinalizer(scope, Console.log("Release memory"))
// Do some work...
yield* Console.log("Performing operations...")
// Close scope - finalizers run in reverse order of registration
yield* Scope.close(scope, Exit.succeed("Success!"))
// Output: "Release memory", "Close file handle", "Close database connection"
})
close(const toClose: Scope.Closeableconst toClose: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
import ExitExit.const failCause: <E>(
cause: Cause.Cause<E>
) => Exit<never, E>
Creates a failed Exit from a Cause.
When to use
Use when you already have a Cause<E> and want to wrap it in an Exit
for advanced error handling where you need full control over the Cause
structure.
Details
Returns a Failure<never, E>. If you only have an error value, use
fail
instead.
Example (Creating a failed Exit from a Cause)
import { Cause, Exit } from "effect"
const cause = Cause.fail("Something went wrong")
const exit = Exit.failCause(cause)
console.log(Exit.isFailure(exit)) // true
failCause(cause: Cause.Cause<
OutErr | Cause.Done<OutDone>
>
(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
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;
}
Pipeable.pipe<Effect.Effect<void, never, never>, Effect.Effect<Pull.Pull<OutElem1, OutErr1, OutDone1, never>, never, Env1>, Effect.Effect<OutElem1, any, Env1>>(this: Effect.Effect<...>, ab: (_: Effect.Effect<void, never, never>) => Effect.Effect<Pull.Pull<OutElem1, OutErr1, OutDone1, never>, never, Env1>, bc: (_: Effect.Effect<Pull.Pull<OutElem1, OutErr1, OutDone1, never>, never, Env1>) => Effect.Effect<...>): Effect.Effect<...> (+21 overloads)pipe(
import EffectEffect.const andThen: {
<A, B, E2, R2>(
f: (a: A) => Effect<B, E2, R2>
): <E, R>(
self: Effect<A, E, R>
) => Effect<B, E | E2, R | R2>
<B, E2, R2>(f: Effect<B, E2, R2>): <A, E, R>(
self: Effect<A, E, R>
) => Effect<B, E | E2, R | R2>
<A, E, R, B, E2, R2>(
self: Effect<A, E, R>,
f: (a: A) => Effect<B, E2, R2>
): Effect<B, E | E2, R | R2>
<A, E, R, B, E2, R2>(
self: Effect<A, E, R>,
f: Effect<B, E2, R2>
): Effect<B, E | E2, R | R2>
}
const toTransform: <
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>(
channel: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => (
upstream: Pull.Pull<InElem, InErr, InDone>,
scope: Scope.Scope
) => Effect.Effect<
Pull.Pull<OutElem, OutErr, OutDone>,
never,
Env
>
Converts a Channel back to its underlying transformation function.
Example (Extracting channel transforms)
import { Channel } from "effect"
const channel = Channel.succeed(42)
const transform = Channel.toTransform(channel)
// transform can now be used directly
toTransform(f: (
d: Cause.Cause<OutErr>
) => Channel<
OutElem1,
OutErr1,
OutDone1,
InElem1,
InErr1,
InDone1,
Env1
>
cause: Cause.Cause<
OutErr | Cause.Done<OutDone>
>
(parameter) cause: {
reasons: ReadonlyArray<Reason<E>>;
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 CauseCause.type Cause.Cause = /*unresolved*/ anyCause<function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, f: (d: Cause.Cause<OutErr>) => Channel<OutElem1, OutErr1, OutDone1, InElem1, InErr1, InDone1, Env1>): Channel<OutElem | OutElem1, OutErr1, OutDone | OutDone1, InElem & InElem1, InErr & InErr1, InDone & InDone1, Env | Env1>OutErr>))(upstream: Pull.Pull<
InElem & InElem1,
InErr & InErr1,
InDone & InDone1,
never
>
(parameter) upstream: {
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;
}
let forkedScope: Scope.Closeablelet forkedScope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
import EffectEffect.const flatMap: {
<A, B, E1, R1>(
f: (a: A) => Effect<B, E1, R1>
): <E, R>(
self: Effect<A, E, R>
) => Effect<B, E1 | E, R1 | R>
<A, E, R, B, E1, R1>(
self: Effect<A, E, R>,
f: (a: A) => Effect<B, E1, R1>
): Effect<B, E | E1, R | R1>
}
childPull: Pull.Pull<
OutElem1,
OutErr1,
OutDone1,
never
>
(parameter) childPull: {
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;
}
let currentPull: Pull.Pull<
OutElem | OutElem1,
OutErr1,
OutDone | OutDone1,
Env | Env1
>
let currentPull: {
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;
}
childPull: Pull.Pull<
OutElem1,
OutErr1,
OutDone1,
never
>
(parameter) childPull: {
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;
}
childPull: Pull.Pull<
OutElem1,
OutErr1,
OutDone1,
never
>
(parameter) childPull: {
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 suspend: <A, E, R>(
effect: LazyArg<Effect<A, E, R>>
) => Effect<A, E, R>
Creates an Effect lazily, delaying construction until it is needed.
When to use
Use when you need to defer the evaluation of an effect until it is required.
Details
suspend takes a thunk that represents an effect and delays creating it
until the suspended effect is evaluated. This is useful for optimizing
expensive computations, managing circular dependencies such as recursive
functions, and helping TypeScript unify return types when branches construct
different effects. Any side effects or scoped captures inside the thunk are
re-executed on each invocation.
Example (Lazily evaluating side effects)
import { Effect } from "effect"
let i = 0
const bad = Effect.succeed(i++)
const good = Effect.suspend(() => Effect.succeed(i++))
console.log(Effect.runSync(bad)) // Output: 0
console.log(Effect.runSync(bad)) // Output: 0
console.log(Effect.runSync(good)) // Output: 1
console.log(Effect.runSync(good)) // Output: 2
Example (Suspending recursive Fibonacci evaluation)
import { Effect } from "effect"
const blowsUp = (n: number): Effect.Effect<number> =>
n < 2
? Effect.succeed(1)
: Effect.zipWith(blowsUp(n - 1), blowsUp(n - 2), (a, b) => a + b)
// console.log(Effect.runSync(blowsUp(32)))
// crash: JavaScript heap out of memory
const allGood = (n: number): Effect.Effect<number> =>
n < 2
? Effect.succeed(1)
: Effect.zipWith(
Effect.suspend(() => allGood(n - 1)),
Effect.suspend(() => allGood(n - 2)),
(a, b) => a + b
)
console.log(Effect.runSync(allGood(32)))
// Output: 3524578
Example (Helping TypeScript infer recursive effect types)
import { Effect } from "effect"
// Without suspend, TypeScript may struggle with type inference.
// Inferred type:
// (a: number, b: number) =>
// Effect<never, Error, never> | Effect<number, never, never>
const withoutSuspend = (a: number, b: number) =>
b === 0
? Effect.fail(new Error("Cannot divide by zero"))
: Effect.succeed(a / b)
// Using suspend to unify return types.
// Inferred type:
// (a: number, b: number) => Effect<number, Error, never>
const withSuspend = (a: number, b: number) =>
Effect.suspend(() =>
b === 0
? Effect.fail(new Error("Cannot divide by zero"))
: Effect.succeed(a / b)
)
suspend(() => let currentPull: Pull.Pull<
OutElem | OutElem1,
OutErr1,
OutDone | OutDone1,
Env | Env1
>
let currentPull: {
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;
}
Referenced by 4 symbols