<OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(
that: Channel<
OutElem2,
OutErr2,
OutDone2,
OutElem,
never,
OutDone,
Env2
>
): <OutErr, InElem, InErr, InDone, Env>(
self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>
) => Channel<
OutElem2,
OutErr | OutErr2,
OutDone2,
InElem,
InErr,
InDone,
Env2 | Env
>
<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env,
OutElem2,
OutErr2,
OutDone2,
Env2
>(
self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>,
that: Channel<
OutElem2,
OutErr2,
OutDone2,
OutElem,
never,
OutDone,
Env2
>
): Channel<
OutElem2,
OutErr | OutErr2,
OutDone2,
InElem,
InErr,
InDone,
Env2 | Env
>Returns a new channel that pipes the output of this channel into the specified channel and preserves this channel's failures without providing them to the other channel for observation.
Example (Piping while preserving failures)
import { Channel, Data } from "effect"
class SourceError extends Data.TaggedError("SourceError")<{
readonly code: number
}> {}
// Create a failing source channel
const failingSource = Channel.fail(new SourceError({ code: 404 }))
const safeTransform = Channel.succeed("transformed")
// Pipe while preserving source failures
const safePipedChannel = Channel.pipeToOrFail(failingSource, safeTransform)
// Source errors are preserved and not sent to transform channelsequencing
Source effect/Channel.ts:656335 lines
export const const pipeToOrFail: {
<
OutElem2,
OutErr2,
OutDone2,
OutElem,
OutDone,
Env2
>(
that: Channel<
OutElem2,
OutErr2,
OutDone2,
OutElem,
never,
OutDone,
Env2
>
): <OutErr, InElem, InErr, InDone, Env>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => Channel<
OutElem2,
OutErr | OutErr2,
OutDone2,
InElem,
InErr,
InDone,
Env2 | Env
>
<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env,
OutElem2,
OutErr2,
OutDone2,
Env2
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
that: Channel<
OutElem2,
OutErr2,
OutDone2,
OutElem,
never,
OutDone,
Env2
>
): Channel<
OutElem2,
OutErr | OutErr2,
OutDone2,
InElem,
InErr,
InDone,
Env2 | Env
>
}
Returns a new channel that pipes the output of this channel into the
specified channel and preserves this channel's failures without providing
them to the other channel for observation.
Example (Piping while preserving failures)
import { Channel, Data } from "effect"
class SourceError extends Data.TaggedError("SourceError")<{
readonly code: number
}> {}
// Create a failing source channel
const failingSource = Channel.fail(new SourceError({ code: 404 }))
const safeTransform = Channel.succeed("transformed")
// Pipe while preserving source failures
const safePipedChannel = Channel.pipeToOrFail(failingSource, safeTransform)
// Source errors are preserved and not sent to transform channel
pipeToOrFail: {
<function (type parameter) OutElem2 in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem2, function (type parameter) OutErr2 in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr2, function (type parameter) OutDone2 in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone2, function (type parameter) OutElem in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem, function (type parameter) OutDone in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone, function (type parameter) Env2 in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env2>(
that: Channel<
OutElem2,
OutErr2,
OutDone2,
OutElem,
never,
OutDone,
Env2
>
(parameter) that: {
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) OutElem2 in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem2, function (type parameter) OutErr2 in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr2, function (type parameter) OutDone2 in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone2, function (type parameter) OutElem in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem, never, function (type parameter) OutDone in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone, function (type parameter) Env2 in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env2>
): <function (type parameter) OutErr in <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr, function (type parameter) InElem in <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InElem, function (type parameter) InErr in <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InErr, function (type parameter) InDone in <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InDone, function (type parameter) Env in <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>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 <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem, function (type parameter) OutErr in <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr, function (type parameter) OutDone in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone, function (type parameter) InElem in <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InElem, function (type parameter) InErr in <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InErr, function (type parameter) InDone in <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InDone, function (type parameter) Env in <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>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) OutElem2 in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem2, function (type parameter) OutErr in <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr | function (type parameter) OutErr2 in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr2, function (type parameter) OutDone2 in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone2, function (type parameter) InElem in <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InElem, function (type parameter) InErr in <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InErr, function (type parameter) InDone in <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InDone, function (type parameter) Env2 in <OutElem2, OutErr2, OutDone2, OutElem, OutDone, Env2>(that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env2 | function (type parameter) Env in <OutErr, InElem, InErr, InDone, Env>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env>
<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env, function (type parameter) OutElem2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem2, function (type parameter) OutErr2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr2, function (type parameter) OutDone2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone2, function (type parameter) Env2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env2>(
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, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env>,
that: Channel<
OutElem2,
OutErr2,
OutDone2,
OutElem,
never,
OutDone,
Env2
>
(parameter) that: {
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) OutElem2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem2, function (type parameter) OutErr2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr2, function (type parameter) OutDone2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone2, function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem, never, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone, function (type parameter) Env2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env2>
): 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) OutElem2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem2, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr | function (type parameter) OutErr2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr2, function (type parameter) OutDone2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone2, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InDone, function (type parameter) Env2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env2 | function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env>
} = dual<(...args: Array<any>) => any, <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>>(arity: 2, body: <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>): ((...args: Array<any>) => any) & (<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>) => Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>) (+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, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env, function (type parameter) OutElem2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem2, function (type parameter) OutErr2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr2, function (type parameter) OutDone2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone2, function (type parameter) Env2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env2>(
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, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env>,
that: Channel<
OutElem2,
OutErr2,
OutDone2,
OutElem,
never,
OutDone,
Env2
>
(parameter) that: {
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) OutElem2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem2, function (type parameter) OutErr2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr2, function (type parameter) OutDone2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone2, function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem, never, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone, function (type parameter) Env2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env2>
): 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) OutElem2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem2, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr | function (type parameter) OutErr2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr2, function (type parameter) OutDone2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone2, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>InDone, function (type parameter) Env2 in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env2 | function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>Env> =>
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, InErr, InDone, 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;
}
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>
}
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, InErr, InDone, 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;
}
upstream: Pull.Pull<
OutElem,
OutErr,
OutDone,
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;
}
const upstreamPull: Pull.Pull<
OutElem,
never,
OutDone,
never
>
const upstreamPull: {
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 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>
}
upstream: Pull.Pull<
OutElem,
OutErr,
OutDone,
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;
}
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.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 EffectEffect.const die: (
defect: unknown
) => Effect<never>
Creates an effect that terminates a fiber with a specified error.
When to use
Use when you need an Effect to report an unrecoverable defect instead of a
typed error.
Details
The die function is used to signal a defect, which represents a critical
and unexpected error in the code. When invoked, it produces an effect that
does not handle the error and instead terminates the fiber.
The error channel of the resulting effect is of type never, indicating that
it cannot recover from this failure.
Example (Failing on division by zero)
import { Effect } from "effect"
const divide = (a: number, b: number) =>
b === 0
? Effect.die(new Error("Cannot divide by zero"))
: Effect.succeed(a / b)
// ┌─── Effect<number, never, never>
// ▼
const program = divide(1, 0)
Effect.runPromise(program).catch(console.error)
// Output:
// (FiberFailure) Error: Cannot divide by zero
// ...stack trace...
die(import CauseCause.Done(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) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutElem, never, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutDone>
return 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(that: Channel<
OutElem2,
OutErr2,
OutDone2,
OutElem,
never,
OutDone,
Env2
>
(parameter) that: {
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; <…;
}
const upstreamPull: Pull.Pull<
OutElem,
never,
OutDone,
never
>
const upstreamPull: {
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;
}
pull: Pull.Pull<
OutElem2,
OutErr2,
OutDone2,
never
>
(parameter) pull: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
import EffectEffect.const catchDefect: {
<A2, E2, R2>(
f: (defect: unknown) => Effect<A2, E2, R2>
): <A, E, R>(
self: Effect<A, E, R>
) => Effect<A2 | A, E2 | E, R2 | R>
<A, E, R, A2, E2, R2>(
self: Effect<A, E, R>,
f: (defect: unknown) => Effect<A2, E2, R2>
): Effect<A | A2, E | E2, R | R2>
}
pull: Pull.Pull<
OutElem2,
OutErr2,
OutDone2,
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;
}
defect: unknowndefect) =>
import CauseCause.isDone(defect: unknowndefect) ? 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(defect: Cause.Done<any>(parameter) defect: {
_tag: "Done";
value: A;
}
import CauseCause.type Cause.Cause = /*unresolved*/ anyCause<function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, OutElem2, OutErr2, OutDone2, Env2>(self: Channel<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>, that: Channel<OutElem2, OutErr2, OutDone2, OutElem, never, OutDone, Env2>): Channel<OutElem2, OutErr | OutErr2, OutDone2, InElem, InErr, InDone, Env2 | Env>OutErr>) : import EffectEffect.const die: (
defect: unknown
) => Effect<never>
Creates an effect that terminates a fiber with a specified error.
When to use
Use when you need an Effect to report an unrecoverable defect instead of a
typed error.
Details
The die function is used to signal a defect, which represents a critical
and unexpected error in the code. When invoked, it produces an effect that
does not handle the error and instead terminates the fiber.
The error channel of the resulting effect is of type never, indicating that
it cannot recover from this failure.
Example (Failing on division by zero)
import { Effect } from "effect"
const divide = (a: number, b: number) =>
b === 0
? Effect.die(new Error("Cannot divide by zero"))
: Effect.succeed(a / b)
// ┌─── Effect<number, never, never>
// ▼
const program = divide(1, 0)
Effect.runPromise(program).catch(console.error)
// Output:
// (FiberFailure) Error: Cannot divide by zero
// ...stack trace...
die(defect: unknowndefect)
)
)
})
)
)Referenced by 2 symbols