<In extends Schema.Constraint, Out extends Schema.Constraint>(options: {
readonly inputSchema: In
readonly outputSchema: Out
}): <OutErr, OutDone, InErr, InDone, R>(
self: Channel.Channel<
Arr.NonEmptyReadonlyArray<Out["Encoded"]>,
OutErr,
OutDone,
Arr.NonEmptyReadonlyArray<In["Encoded"]>,
Schema.SchemaError | InErr,
InDone,
R
>
) => Channel.Channel<
Arr.NonEmptyReadonlyArray<Out["Type"]>,
Schema.SchemaError | OutErr,
OutDone,
Arr.NonEmptyReadonlyArray<In["Type"]>,
InErr,
InDone,
R | In["EncodingServices"] | Out["DecodingServices"]
>
<
Out extends Schema.Constraint,
OutErr,
OutDone,
In extends Schema.Constraint,
InErr,
InDone,
R
>(
self: Channel.Channel<
Arr.NonEmptyReadonlyArray<Out["Encoded"]>,
OutErr,
OutDone,
Arr.NonEmptyReadonlyArray<In["Encoded"]>,
Schema.SchemaError | InErr,
InDone,
R
>,
options: { readonly inputSchema: In; readonly outputSchema: Out }
): Channel.Channel<
Arr.NonEmptyReadonlyArray<Out["Type"]>,
Schema.SchemaError | OutErr,
OutDone,
Arr.NonEmptyReadonlyArray<In["Type"]>,
InErr,
InDone,
R | In["EncodingServices"] | Out["DecodingServices"]
>Wraps a channel so callers work with typed input and output chunks while the wrapped channel uses encoded chunks.
When to use
Use to expose typed input and output at a bidirectional channel boundary while the wrapped channel continues to operate on schema-encoded chunks.
Details
Values sent into the resulting channel are encoded with inputSchema before
reaching the wrapped channel. Values emitted by the wrapped channel are
decoded with outputSchema before they are emitted downstream. Schema
failures are surfaced as SchemaError.
Source effect/ChannelSchema.ts:16873 lines
export const const duplex: {
<
In extends Schema.Constraint,
Out extends Schema.Constraint
>(options: {
readonly inputSchema: In
readonly outputSchema: Out
}): <OutErr, OutDone, InErr, InDone, R>(
self: Channel.Channel<
Arr.NonEmptyReadonlyArray<Out["Encoded"]>,
OutErr,
OutDone,
Arr.NonEmptyReadonlyArray<In["Encoded"]>,
Schema.SchemaError | InErr,
InDone,
R
>
) => Channel.Channel<
Arr.NonEmptyReadonlyArray<Out["Type"]>,
Schema.SchemaError | OutErr,
OutDone,
Arr.NonEmptyReadonlyArray<In["Type"]>,
InErr,
InDone,
| R
| In["EncodingServices"]
| Out["DecodingServices"]
>
<
Out extends Schema.Constraint,
OutErr,
OutDone,
In extends Schema.Constraint,
InErr,
InDone,
R
>(
self: Channel.Channel<
Arr.NonEmptyReadonlyArray<Out["Encoded"]>,
OutErr,
OutDone,
Arr.NonEmptyReadonlyArray<In["Encoded"]>,
Schema.SchemaError | InErr,
InDone,
R
>,
options: {
readonly inputSchema: In
readonly outputSchema: Out
}
): Channel.Channel<
Arr.NonEmptyReadonlyArray<Out["Type"]>,
Schema.SchemaError | OutErr,
OutDone,
Arr.NonEmptyReadonlyArray<In["Type"]>,
InErr,
InDone,
| R
| In["EncodingServices"]
| Out["DecodingServices"]
>
}
Wraps a channel so callers work with typed input and output chunks while the
wrapped channel uses encoded chunks.
When to use
Use to expose typed input and output at a bidirectional channel boundary
while the wrapped channel continues to operate on schema-encoded chunks.
Details
Values sent into the resulting channel are encoded with inputSchema before
reaching the wrapped channel. Values emitted by the wrapped channel are
decoded with outputSchema before they are emitted downstream. Schema
failures are surfaced as SchemaError.
duplex: {
<function (type parameter) In in <In extends Schema.Constraint, Out extends Schema.Constraint>(options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>) => Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import SchemaSchema.Constraint, function (type parameter) Out in <In extends Schema.Constraint, Out extends Schema.Constraint>(options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>) => Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import SchemaSchema.Constraint>(options: {
readonly inputSchema: In
readonly outputSchema: Out
}
inputSchema: In extends Schema.ConstraintinputSchema: function (type parameter) In in <In extends Schema.Constraint, Out extends Schema.Constraint>(options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>) => Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
outputSchema: Out extends Schema.ConstraintoutputSchema: function (type parameter) Out in <In extends Schema.Constraint, Out extends Schema.Constraint>(options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>) => Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) OutErr in <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>OutErr, function (type parameter) OutDone in <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>OutDone, function (type parameter) InErr in <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>InErr, function (type parameter) InDone in <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>InDone, function (type parameter) R in <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>R>(
self: Channel.Channel<
Arr.NonEmptyReadonlyArray<Out["Encoded"]>,
OutErr,
OutDone,
Arr.NonEmptyReadonlyArray<In["Encoded"]>,
Schema.SchemaError | InErr,
InDone,
R
>
(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; <…;
}
import ChannelChannel.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<
import ArrArr.type NonEmptyReadonlyArray<A> = readonly [
A,
...A[]
]
A readonly array guaranteed to have at least one element.
When to use
Use when non-emptiness must be tracked at the type level while preventing mutation.
Many Array module functions accept or return this type.
Example (Typing a non-empty array)
import type { Array } from "effect"
const nonEmpty: Array.NonEmptyReadonlyArray<number> = [1, 2, 3]
const head: number = nonEmpty[0] // guaranteed to exist
NonEmptyReadonlyArray<function (type parameter) Out in <In extends Schema.Constraint, Out extends Schema.Constraint>(options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>) => Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) OutErr in <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>OutErr,
function (type parameter) OutDone in <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>OutDone,
import ArrArr.type NonEmptyReadonlyArray<A> = readonly [
A,
...A[]
]
A readonly array guaranteed to have at least one element.
When to use
Use when non-emptiness must be tracked at the type level while preventing mutation.
Many Array module functions accept or return this type.
Example (Typing a non-empty array)
import type { Array } from "effect"
const nonEmpty: Array.NonEmptyReadonlyArray<number> = [1, 2, 3]
const head: number = nonEmpty[0] // guaranteed to exist
NonEmptyReadonlyArray<function (type parameter) In in <In extends Schema.Constraint, Out extends Schema.Constraint>(options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>) => Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import SchemaSchema.class SchemaError
export SchemaError
class SchemaError {
message: string;
toString: () => string;
name: string;
stack: string;
cause: unknown;
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; <…;
toJSON: () => unknown;
_tag: Tag;
issue: Issue;
}
Error thrown (or returned as the error channel value) when schema decoding
or encoding fails.
Details
The issue field contains a structured
SchemaIssue.Issue
tree describing
every validation failure, including the path to the problematic value,
expected types, and actual values received. message renders the issue tree
as a human-readable string.
Use
isSchemaError
to narrow an unknown value to SchemaError.
Example (Catching a SchemaError)
import { Schema } from "effect"
try {
Schema.decodeUnknownSync(Schema.Number)("not a number")
} catch (err) {
if (Schema.isSchemaError(err)) {
console.log(err.message)
// Expected number, actual "not a number"
}
}
SchemaError | function (type parameter) InErr in <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>InErr,
function (type parameter) InDone in <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>InDone,
function (type parameter) R in <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>R
>
) => import ChannelChannel.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<
import ArrArr.type NonEmptyReadonlyArray<A> = readonly [
A,
...A[]
]
A readonly array guaranteed to have at least one element.
When to use
Use when non-emptiness must be tracked at the type level while preventing mutation.
Many Array module functions accept or return this type.
Example (Typing a non-empty array)
import type { Array } from "effect"
const nonEmpty: Array.NonEmptyReadonlyArray<number> = [1, 2, 3]
const head: number = nonEmpty[0] // guaranteed to exist
NonEmptyReadonlyArray<function (type parameter) Out in <In extends Schema.Constraint, Out extends Schema.Constraint>(options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>) => Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import SchemaSchema.class SchemaError
export SchemaError
class SchemaError {
message: string;
toString: () => string;
name: string;
stack: string;
cause: unknown;
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; <…;
toJSON: () => unknown;
_tag: Tag;
issue: Issue;
}
Error thrown (or returned as the error channel value) when schema decoding
or encoding fails.
Details
The issue field contains a structured
SchemaIssue.Issue
tree describing
every validation failure, including the path to the problematic value,
expected types, and actual values received. message renders the issue tree
as a human-readable string.
Use
isSchemaError
to narrow an unknown value to SchemaError.
Example (Catching a SchemaError)
import { Schema } from "effect"
try {
Schema.decodeUnknownSync(Schema.Number)("not a number")
} catch (err) {
if (Schema.isSchemaError(err)) {
console.log(err.message)
// Expected number, actual "not a number"
}
}
SchemaError | function (type parameter) OutErr in <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>OutErr,
function (type parameter) OutDone in <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>OutDone,
import ArrArr.type NonEmptyReadonlyArray<A> = readonly [
A,
...A[]
]
A readonly array guaranteed to have at least one element.
When to use
Use when non-emptiness must be tracked at the type level while preventing mutation.
Many Array module functions accept or return this type.
Example (Typing a non-empty array)
import type { Array } from "effect"
const nonEmpty: Array.NonEmptyReadonlyArray<number> = [1, 2, 3]
const head: number = nonEmpty[0] // guaranteed to exist
NonEmptyReadonlyArray<function (type parameter) In in <In extends Schema.Constraint, Out extends Schema.Constraint>(options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>) => Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) InErr in <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>InErr,
function (type parameter) InDone in <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>InDone,
function (type parameter) R in <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>R | function (type parameter) In in <In extends Schema.Constraint, Out extends Schema.Constraint>(options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>) => Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) Out in <In extends Schema.Constraint, Out extends Schema.Constraint>(options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): <OutErr, OutDone, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>) => Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) Out in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import SchemaSchema.Constraint, function (type parameter) OutErr in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) OutDone in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) In in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import SchemaSchema.Constraint, function (type parameter) InErr in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) InDone in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) R in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
self: Channel.Channel<
Arr.NonEmptyReadonlyArray<Out["Encoded"]>,
OutErr,
OutDone,
Arr.NonEmptyReadonlyArray<In["Encoded"]>,
Schema.SchemaError | InErr,
InDone,
R
>
(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; <…;
}
import ChannelChannel.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<
import ArrArr.type NonEmptyReadonlyArray<A> = readonly [
A,
...A[]
]
A readonly array guaranteed to have at least one element.
When to use
Use when non-emptiness must be tracked at the type level while preventing mutation.
Many Array module functions accept or return this type.
Example (Typing a non-empty array)
import type { Array } from "effect"
const nonEmpty: Array.NonEmptyReadonlyArray<number> = [1, 2, 3]
const head: number = nonEmpty[0] // guaranteed to exist
NonEmptyReadonlyArray<function (type parameter) Out in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) OutErr in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) OutDone in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import ArrArr.type NonEmptyReadonlyArray<A> = readonly [
A,
...A[]
]
A readonly array guaranteed to have at least one element.
When to use
Use when non-emptiness must be tracked at the type level while preventing mutation.
Many Array module functions accept or return this type.
Example (Typing a non-empty array)
import type { Array } from "effect"
const nonEmpty: Array.NonEmptyReadonlyArray<number> = [1, 2, 3]
const head: number = nonEmpty[0] // guaranteed to exist
NonEmptyReadonlyArray<function (type parameter) In in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import SchemaSchema.class SchemaError
export SchemaError
class SchemaError {
message: string;
toString: () => string;
name: string;
stack: string;
cause: unknown;
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; <…;
toJSON: () => unknown;
_tag: Tag;
issue: Issue;
}
Error thrown (or returned as the error channel value) when schema decoding
or encoding fails.
Details
The issue field contains a structured
SchemaIssue.Issue
tree describing
every validation failure, including the path to the problematic value,
expected types, and actual values received. message renders the issue tree
as a human-readable string.
Use
isSchemaError
to narrow an unknown value to SchemaError.
Example (Catching a SchemaError)
import { Schema } from "effect"
try {
Schema.decodeUnknownSync(Schema.Number)("not a number")
} catch (err) {
if (Schema.isSchemaError(err)) {
console.log(err.message)
// Expected number, actual "not a number"
}
}
SchemaError | function (type parameter) InErr in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) InDone in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) R in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
options: {
readonly inputSchema: In
readonly outputSchema: Out
}
inputSchema: In extends Schema.ConstraintinputSchema: function (type parameter) In in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
outputSchema: Out extends Schema.ConstraintoutputSchema: function (type parameter) Out in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import ChannelChannel.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<
import ArrArr.type NonEmptyReadonlyArray<A> = readonly [
A,
...A[]
]
A readonly array guaranteed to have at least one element.
When to use
Use when non-emptiness must be tracked at the type level while preventing mutation.
Many Array module functions accept or return this type.
Example (Typing a non-empty array)
import type { Array } from "effect"
const nonEmpty: Array.NonEmptyReadonlyArray<number> = [1, 2, 3]
const head: number = nonEmpty[0] // guaranteed to exist
NonEmptyReadonlyArray<function (type parameter) Out in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import SchemaSchema.class SchemaError
export SchemaError
class SchemaError {
message: string;
toString: () => string;
name: string;
stack: string;
cause: unknown;
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; <…;
toJSON: () => unknown;
_tag: Tag;
issue: Issue;
}
Error thrown (or returned as the error channel value) when schema decoding
or encoding fails.
Details
The issue field contains a structured
SchemaIssue.Issue
tree describing
every validation failure, including the path to the problematic value,
expected types, and actual values received. message renders the issue tree
as a human-readable string.
Use
isSchemaError
to narrow an unknown value to SchemaError.
Example (Catching a SchemaError)
import { Schema } from "effect"
try {
Schema.decodeUnknownSync(Schema.Number)("not a number")
} catch (err) {
if (Schema.isSchemaError(err)) {
console.log(err.message)
// Expected number, actual "not a number"
}
}
SchemaError | function (type parameter) OutErr in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) OutDone in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import ArrArr.type NonEmptyReadonlyArray<A> = readonly [
A,
...A[]
]
A readonly array guaranteed to have at least one element.
When to use
Use when non-emptiness must be tracked at the type level while preventing mutation.
Many Array module functions accept or return this type.
Example (Typing a non-empty array)
import type { Array } from "effect"
const nonEmpty: Array.NonEmptyReadonlyArray<number> = [1, 2, 3]
const head: number = nonEmpty[0] // guaranteed to exist
NonEmptyReadonlyArray<function (type parameter) In in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) InErr in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) InDone in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) R in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) In in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) Out in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
dual<(...args: Array<any>) => any, <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}) => Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>>(arity: 2, body: <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}) => Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>): ((...args: Array<any>) => any) & (<Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}) => Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>) (+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) Out in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import SchemaSchema.Constraint, function (type parameter) OutErr in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) OutDone in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) In in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import SchemaSchema.Constraint, function (type parameter) InErr in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) InDone in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) R in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
self: Channel.Channel<
Arr.NonEmptyReadonlyArray<Out["Encoded"]>,
OutErr,
OutDone,
Arr.NonEmptyReadonlyArray<In["Encoded"]>,
Schema.SchemaError | InErr,
InDone,
R
>
(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; <…;
}
import ChannelChannel.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<
import ArrArr.type NonEmptyReadonlyArray<A> = readonly [
A,
...A[]
]
A readonly array guaranteed to have at least one element.
When to use
Use when non-emptiness must be tracked at the type level while preventing mutation.
Many Array module functions accept or return this type.
Example (Typing a non-empty array)
import type { Array } from "effect"
const nonEmpty: Array.NonEmptyReadonlyArray<number> = [1, 2, 3]
const head: number = nonEmpty[0] // guaranteed to exist
NonEmptyReadonlyArray<function (type parameter) Out in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) OutErr in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) OutDone in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import ArrArr.type NonEmptyReadonlyArray<A> = readonly [
A,
...A[]
]
A readonly array guaranteed to have at least one element.
When to use
Use when non-emptiness must be tracked at the type level while preventing mutation.
Many Array module functions accept or return this type.
Example (Typing a non-empty array)
import type { Array } from "effect"
const nonEmpty: Array.NonEmptyReadonlyArray<number> = [1, 2, 3]
const head: number = nonEmpty[0] // guaranteed to exist
NonEmptyReadonlyArray<function (type parameter) In in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import SchemaSchema.class SchemaError
export SchemaError
class SchemaError {
message: string;
toString: () => string;
name: string;
stack: string;
cause: unknown;
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; <…;
toJSON: () => unknown;
_tag: Tag;
issue: Issue;
}
Error thrown (or returned as the error channel value) when schema decoding
or encoding fails.
Details
The issue field contains a structured
SchemaIssue.Issue
tree describing
every validation failure, including the path to the problematic value,
expected types, and actual values received. message renders the issue tree
as a human-readable string.
Use
isSchemaError
to narrow an unknown value to SchemaError.
Example (Catching a SchemaError)
import { Schema } from "effect"
try {
Schema.decodeUnknownSync(Schema.Number)("not a number")
} catch (err) {
if (Schema.isSchemaError(err)) {
console.log(err.message)
// Expected number, actual "not a number"
}
}
SchemaError | function (type parameter) InErr in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) InDone in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) R in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
options: {
readonly inputSchema: In
readonly outputSchema: Out
}
inputSchema: In extends Schema.ConstraintinputSchema: function (type parameter) In in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
outputSchema: Out extends Schema.ConstraintoutputSchema: function (type parameter) Out in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import ChannelChannel.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<
import ArrArr.type NonEmptyReadonlyArray<A> = readonly [
A,
...A[]
]
A readonly array guaranteed to have at least one element.
When to use
Use when non-emptiness must be tracked at the type level while preventing mutation.
Many Array module functions accept or return this type.
Example (Typing a non-empty array)
import type { Array } from "effect"
const nonEmpty: Array.NonEmptyReadonlyArray<number> = [1, 2, 3]
const head: number = nonEmpty[0] // guaranteed to exist
NonEmptyReadonlyArray<function (type parameter) Out in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import SchemaSchema.class SchemaError
export SchemaError
class SchemaError {
message: string;
toString: () => string;
name: string;
stack: string;
cause: unknown;
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; <…;
toJSON: () => unknown;
_tag: Tag;
issue: Issue;
}
Error thrown (or returned as the error channel value) when schema decoding
or encoding fails.
Details
The issue field contains a structured
SchemaIssue.Issue
tree describing
every validation failure, including the path to the problematic value,
expected types, and actual values received. message renders the issue tree
as a human-readable string.
Use
isSchemaError
to narrow an unknown value to SchemaError.
Example (Catching a SchemaError)
import { Schema } from "effect"
try {
Schema.decodeUnknownSync(Schema.Number)("not a number")
} catch (err) {
if (Schema.isSchemaError(err)) {
console.log(err.message)
// Expected number, actual "not a number"
}
}
SchemaError | function (type parameter) OutErr in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) OutDone in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
import ArrArr.type NonEmptyReadonlyArray<A> = readonly [
A,
...A[]
]
A readonly array guaranteed to have at least one element.
When to use
Use when non-emptiness must be tracked at the type level while preventing mutation.
Many Array module functions accept or return this type.
Example (Typing a non-empty array)
import type { Array } from "effect"
const nonEmpty: Array.NonEmptyReadonlyArray<number> = [1, 2, 3]
const head: number = nonEmpty[0] // guaranteed to exist
NonEmptyReadonlyArray<function (type parameter) In in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) InErr in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) InDone in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) R in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) In in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) Out in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
const encode: <
S extends Schema.Constraint
>(
schema: S
) => <
IE = never,
Done = unknown
>() => Channel.Channel<
Arr.NonEmptyReadonlyArray<S["Encoded"]>,
IE | Schema.SchemaError,
Done,
Arr.NonEmptyReadonlyArray<S["Type"]>,
IE,
Done,
S["EncodingServices"]
>
Creates a channel that encodes non-empty chunks of schema values into the
schema's encoded representation.
When to use
Use to encode typed channel input into the schema's encoded representation
before passing chunks to an encoded downstream boundary.
Details
Encoding failures are emitted as SchemaError, and any encoding services
required by the schema become channel requirements.
encode(options: {
readonly inputSchema: In
readonly outputSchema: Out
}
inputSchema: In extends Schema.ConstraintinputSchema)<function (type parameter) InErr in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
function (type parameter) InDone in <Out extends Schema.Constraint, OutErr, OutDone, In extends Schema.Constraint, InErr, InDone, R>(self: Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Encoded"]>, OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Encoded"]>, Schema.SchemaError | InErr, InDone, R>, options: {
readonly inputSchema: In;
readonly outputSchema: Out;
}): Channel.Channel<Arr.NonEmptyReadonlyArray<Out["Type"]>, Schema.SchemaError | OutErr, OutDone, Arr.NonEmptyReadonlyArray<In["Type"]>, InErr, InDone, R | In["EncodingServices"] | Out["DecodingServices"]>
Pipeable.pipe<Channel.Channel<readonly [In["Encoded"], ...In["Encoded"][]], Schema.SchemaError | InErr, InDone, readonly [In["Type"], ...In["Type"][]], InErr, InDone, In["EncodingServices"]>, Channel.Channel<readonly [Out["Encoded"], ...Out["Encoded"][]], OutErr, OutDone, readonly [In["Type"], ...In["Type"][]], InErr, InDone, R | In["EncodingServices"]>, Channel.Channel<readonly [Out["Type"], ...Out["Type"][]], Schema.SchemaError | OutErr, ... 4 more ..., R | ... 1 more ... | Out["DecodingServices"]>>(this: Channel.Channel<...>, ab: (_: Channel.Channel<...>) => Channel.Channel<...>, bc: (_: Channel.Channel<...>) => Channel.Channel<...>): Channel.Channel<...> (+21 overloads)pipe(
import ChannelChannel.const pipeTo: {
<
OutElem2,
OutErr2,
OutDone2,
OutElem,
OutErr,
OutDone,
Env2
>(
that: Channel<
OutElem2,
OutErr2,
OutDone2,
OutElem,
OutErr,
OutDone,
Env2
>
): <InElem, InErr, InDone, Env>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => Channel<
OutElem2,
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,
OutErr,
OutDone,
Env2
>
): Channel<
OutElem2,
OutErr2,
OutDone2,
InElem,
InErr,
InDone,
Env2 | Env
>
}
self: Channel.Channel<
Arr.NonEmptyReadonlyArray<Out["Encoded"]>,
OutErr,
OutDone,
Arr.NonEmptyReadonlyArray<In["Encoded"]>,
Schema.SchemaError | InErr,
InDone,
R
>
(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; <…;
}
import ChannelChannel.const pipeTo: {
<
OutElem2,
OutErr2,
OutDone2,
OutElem,
OutErr,
OutDone,
Env2
>(
that: Channel<
OutElem2,
OutErr2,
OutDone2,
OutElem,
OutErr,
OutDone,
Env2
>
): <InElem, InErr, InDone, Env>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => Channel<
OutElem2,
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,
OutErr,
OutDone,
Env2
>
): Channel<
OutElem2,
OutErr2,
OutDone2,
InElem,
InErr,
InDone,
Env2 | Env
>
}
const decode: <
S extends Schema.Constraint
>(
schema: S
) => <
IE = never,
Done = unknown
>() => Channel.Channel<
Arr.NonEmptyReadonlyArray<S["Type"]>,
IE | Schema.SchemaError,
Done,
Arr.NonEmptyReadonlyArray<S["Encoded"]>,
IE,
Done,
S["DecodingServices"]
>
Creates a channel that decodes non-empty chunks from the schema's encoded
representation into schema values.
When to use
Use to validate and decode encoded channel output into typed schema values
before application code consumes it.
Details
Decoding failures are emitted as SchemaError, and any decoding services
required by the schema become channel requirements.
decode(options: {
readonly inputSchema: In
readonly outputSchema: Out
}
outputSchema: Out extends Schema.ConstraintoutputSchema)())
))Referenced by 1 symbols