<OutElem, B extends OutElem>(
refinement: Predicate.Refinement<OutElem, B>
): <OutErr, OutDone, InElem, InErr, InDone, Env>(
self: Channel<
Arr.NonEmptyReadonlyArray<OutElem>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => Channel<
Arr.NonEmptyReadonlyArray<B>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
<OutElem>(predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): <
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>(
self: Channel<
Arr.NonEmptyReadonlyArray<OutElem>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => Channel<
Arr.NonEmptyReadonlyArray<OutElem>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(
self: Channel<
Arr.NonEmptyReadonlyArray<OutElem>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
refinement: Predicate.Refinement<OutElem, B>
): Channel<
Arr.NonEmptyReadonlyArray<B>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(
self: Channel<
Arr.NonEmptyReadonlyArray<OutElem>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
predicate: Predicate.Predicate<Types.NoInfer<OutElem>>
): Channel<
Arr.NonEmptyReadonlyArray<OutElem>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>Filters arrays of elements emitted by a channel, applying the filter to each element within the arrays and only emitting non-empty filtered arrays.
Example (Filtering array output)
import { Array, Channel } from "effect"
const nonEmptyArrayPredicate = Array.isReadonlyArrayNonEmpty
// Create a channel that outputs arrays of mixed data
const arrayChannel = Channel.fromIterable([
Array.make(1, 2, 3, 4, 5),
Array.make(6, 7, 8, 9, 10),
Array.make(11, 12, 13, 14, 15)
]).pipe(Channel.filter(nonEmptyArrayPredicate))
// Filter arrays to keep only even numbers
const evenArraysChannel = Channel.filterArray(arrayChannel, (n) => n % 2 === 0)
// Outputs: [2, 4], [6, 8, 10], [12, 14]
// Note: Only non-empty filtered arrays are emitted
// Arrays that would become empty after filtering are discarded entirely
const oddChannel = Channel.fromIterable([
Array.make(1, 3, 5),
Array.make(2, 4),
Array.make(7, 9)
]).pipe(Channel.filter(nonEmptyArrayPredicate))
const filteredOddChannel = Channel.filterArray(oddChannel, (n) => n % 2 === 0)
// Outputs: [2, 4] (the arrays [1,3,5] and [7,9] are discarded)filtering
Source effect/Channel.ts:338238 lines
export const const filterArray: {
<OutElem, B extends OutElem>(
refinement: Predicate.Refinement<OutElem, B>
): <
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>(
self: Channel<
Arr.NonEmptyReadonlyArray<OutElem>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => Channel<
Arr.NonEmptyReadonlyArray<B>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
<OutElem>(
predicate: Predicate.Predicate<
Types.NoInfer<OutElem>
>
): <
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>(
self: Channel<
Arr.NonEmptyReadonlyArray<OutElem>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => Channel<
Arr.NonEmptyReadonlyArray<OutElem>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env,
B extends OutElem
>(
self: Channel<
Arr.NonEmptyReadonlyArray<OutElem>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
refinement: Predicate.Refinement<OutElem, B>
): Channel<
Arr.NonEmptyReadonlyArray<B>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>(
self: Channel<
Arr.NonEmptyReadonlyArray<OutElem>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
predicate: Predicate.Predicate<
Types.NoInfer<OutElem>
>
): Channel<
Arr.NonEmptyReadonlyArray<OutElem>,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
}
Filters arrays of elements emitted by a channel, applying the filter
to each element within the arrays and only emitting non-empty filtered arrays.
Example (Filtering array output)
import { Array, Channel } from "effect"
const nonEmptyArrayPredicate = Array.isReadonlyArrayNonEmpty
// Create a channel that outputs arrays of mixed data
const arrayChannel = Channel.fromIterable([
Array.make(1, 2, 3, 4, 5),
Array.make(6, 7, 8, 9, 10),
Array.make(11, 12, 13, 14, 15)
]).pipe(Channel.filter(nonEmptyArrayPredicate))
// Filter arrays to keep only even numbers
const evenArraysChannel = Channel.filterArray(arrayChannel, (n) => n % 2 === 0)
// Outputs: [2, 4], [6, 8, 10], [12, 14]
// Note: Only non-empty filtered arrays are emitted
// Arrays that would become empty after filtering are discarded entirely
const oddChannel = Channel.fromIterable([
Array.make(1, 3, 5),
Array.make(2, 4),
Array.make(7, 9)
]).pipe(Channel.filter(nonEmptyArrayPredicate))
const filteredOddChannel = Channel.filterArray(oddChannel, (n) => n % 2 === 0)
// Outputs: [2, 4] (the arrays [1,3,5] and [7,9] are discarded)
filterArray: {
<function (type parameter) OutElem in <OutElem, B extends OutElem>(refinement: Predicate.Refinement<OutElem, B>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem, function (type parameter) B in <OutElem, B extends OutElem>(refinement: Predicate.Refinement<OutElem, B>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>B extends function (type parameter) OutElem in <OutElem, B extends OutElem>(refinement: Predicate.Refinement<OutElem, B>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>(
refinement: Predicate.Refinement<OutElem, B>refinement: import PredicatePredicate.interface Refinement<in A, out B extends A>A predicate that also narrows the input type when it returns true.
When to use
Use when you want a runtime check that refines A to B for TypeScript,
especially when composing type guards with
compose
or safely
checking unknown values.
Details
A refinement returns a type predicate (a is B). Use it with if or
filter to narrow types.
Example (Narrowing unknown values)
import { Predicate } from "effect"
const isString: Predicate.Refinement<unknown, string> = (u): u is string => typeof u === "string"
const data: unknown = "hello"
if (isString(data)) {
console.log(data.toUpperCase())
}
Type-level utilities for working with
Refinement
types.
When to use
Use when you need to extract input and output types from refinement
signatures while writing generic helpers over refinements.
Details
These utilities are type-only, create no runtime values, and the namespace is
erased at runtime.
Example (Extracting refinement types)
import { Predicate } from "effect"
type IsString = Predicate.Refinement<unknown, string>
type Input = Predicate.Refinement.In<IsString>
type Output = Predicate.Refinement.Out<IsString>
Refinement<function (type parameter) OutElem in <OutElem, B extends OutElem>(refinement: Predicate.Refinement<OutElem, B>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem, function (type parameter) B in <OutElem, B extends OutElem>(refinement: Predicate.Refinement<OutElem, B>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>B>
): <function (type parameter) OutErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone, function (type parameter) InElem in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InElem, function (type parameter) InErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InErr, function (type parameter) InDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InDone, function (type parameter) Env in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>Env>(
self: Channel<
Arr.NonEmptyReadonlyArray<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<import ArrArr.type Arr.NonEmptyReadonlyArray = /*unresolved*/ anyNonEmptyReadonlyArray<function (type parameter) OutElem in <OutElem, B extends OutElem>(refinement: Predicate.Refinement<OutElem, B>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>, function (type parameter) OutErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone, function (type parameter) InElem in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InElem, function (type parameter) InErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InErr, function (type parameter) InDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InDone, function (type parameter) Env in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, 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<import ArrArr.type Arr.NonEmptyReadonlyArray = /*unresolved*/ anyNonEmptyReadonlyArray<function (type parameter) B in <OutElem, B extends OutElem>(refinement: Predicate.Refinement<OutElem, B>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>B>, function (type parameter) OutErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone, function (type parameter) InElem in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InElem, function (type parameter) InErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InErr, function (type parameter) InDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InDone, function (type parameter) Env in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>Env>
<function (type parameter) OutElem in <OutElem>(predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>(
predicate: Predicate.Predicate<
Types.NoInfer<OutElem>
>
import PredicatePredicate.interface Predicate<in A>A function that decides whether a value of type A satisfies a condition.
When to use
Use when you want a reusable boolean check for A, especially when you plan
to combine checks with
and
/
or
or pass a predicate to arrays
and iterables.
Details
A predicate returns true or false and never throws by itself. It does not
narrow types unless you use Refinement.
Example (Defining a predicate)
import { Predicate } from "effect"
const isPositive: Predicate.Predicate<number> = (n) => n > 0
console.log(isPositive(1))
Type-level utilities for working with
Predicate
types.
When to use
Use when you need to extract input types from predicate signatures while
writing generic helpers over predicate types.
Details
These utilities are type-only, create no runtime values, and the namespace is
erased at runtime.
Example (Extracting predicate input)
import { Predicate } from "effect"
type IsString = Predicate.Predicate<string>
type Input = Predicate.Predicate.In<IsString>
Predicate<import TypesTypes.type NoInfer<A> = [A][A extends any
? 0
: never]
Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) OutElem in <OutElem>(predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>>
): <function (type parameter) OutErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone, function (type parameter) InElem in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InElem, function (type parameter) InErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InErr, function (type parameter) InDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InDone, function (type parameter) Env in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>Env>(
self: Channel<
Arr.NonEmptyReadonlyArray<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<import ArrArr.type Arr.NonEmptyReadonlyArray = /*unresolved*/ anyNonEmptyReadonlyArray<function (type parameter) OutElem in <OutElem>(predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>, function (type parameter) OutErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone, function (type parameter) InElem in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InElem, function (type parameter) InErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InErr, function (type parameter) InDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InDone, function (type parameter) Env in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, 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<import ArrArr.type Arr.NonEmptyReadonlyArray = /*unresolved*/ anyNonEmptyReadonlyArray<function (type parameter) OutElem in <OutElem>(predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>) => Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>, function (type parameter) OutErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone, function (type parameter) InElem in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InElem, function (type parameter) InErr in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InErr, function (type parameter) InDone in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InDone, function (type parameter) Env in <OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>Env>
<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>Env, function (type parameter) B in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>B extends function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>(
self: Channel<
Arr.NonEmptyReadonlyArray<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<import ArrArr.type Arr.NonEmptyReadonlyArray = /*unresolved*/ anyNonEmptyReadonlyArray<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>Env>,
refinement: Predicate.Refinement<OutElem, B>refinement: import PredicatePredicate.interface Refinement<in A, out B extends A>A predicate that also narrows the input type when it returns true.
When to use
Use when you want a runtime check that refines A to B for TypeScript,
especially when composing type guards with
compose
or safely
checking unknown values.
Details
A refinement returns a type predicate (a is B). Use it with if or
filter to narrow types.
Example (Narrowing unknown values)
import { Predicate } from "effect"
const isString: Predicate.Refinement<unknown, string> = (u): u is string => typeof u === "string"
const data: unknown = "hello"
if (isString(data)) {
console.log(data.toUpperCase())
}
Type-level utilities for working with
Refinement
types.
When to use
Use when you need to extract input and output types from refinement
signatures while writing generic helpers over refinements.
Details
These utilities are type-only, create no runtime values, and the namespace is
erased at runtime.
Example (Extracting refinement types)
import { Predicate } from "effect"
type IsString = Predicate.Refinement<unknown, string>
type Input = Predicate.Refinement.In<IsString>
type Output = Predicate.Refinement.Out<IsString>
Refinement<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem, function (type parameter) B in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>B>
): 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 Arr.NonEmptyReadonlyArray = /*unresolved*/ anyNonEmptyReadonlyArray<function (type parameter) B in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>B>, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env, B extends OutElem>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, refinement: Predicate.Refinement<OutElem, B>): Channel<Arr.NonEmptyReadonlyArray<B>, OutErr, OutDone, InElem, InErr, InDone, Env>Env>
<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>Env>(
self: Channel<
Arr.NonEmptyReadonlyArray<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<import ArrArr.type Arr.NonEmptyReadonlyArray = /*unresolved*/ anyNonEmptyReadonlyArray<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>Env>,
predicate: Predicate.Predicate<
Types.NoInfer<OutElem>
>
import PredicatePredicate.interface Predicate<in A>A function that decides whether a value of type A satisfies a condition.
When to use
Use when you want a reusable boolean check for A, especially when you plan
to combine checks with
and
/
or
or pass a predicate to arrays
and iterables.
Details
A predicate returns true or false and never throws by itself. It does not
narrow types unless you use Refinement.
Example (Defining a predicate)
import { Predicate } from "effect"
const isPositive: Predicate.Predicate<number> = (n) => n > 0
console.log(isPositive(1))
Type-level utilities for working with
Predicate
types.
When to use
Use when you need to extract input types from predicate signatures while
writing generic helpers over predicate types.
Details
These utilities are type-only, create no runtime values, and the namespace is
erased at runtime.
Example (Extracting predicate input)
import { Predicate } from "effect"
type IsString = Predicate.Predicate<string>
type Input = Predicate.Predicate.In<IsString>
Predicate<import TypesTypes.type NoInfer<A> = [A][A extends any
? 0
: never]
Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>>
): 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 Arr.NonEmptyReadonlyArray = /*unresolved*/ anyNonEmptyReadonlyArray<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>Env>
} = dual<(...args: Array<any>) => any, <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>) => Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>>(arity: 2, body: <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>) => Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>): ((...args: Array<any>) => any) & (<OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>) => Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, 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>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>Env>(
self: Channel<
Arr.NonEmptyReadonlyArray<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<import ArrArr.type Arr.NonEmptyReadonlyArray = /*unresolved*/ anyNonEmptyReadonlyArray<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>Env>,
predicate: Predicate.Predicate<
Types.NoInfer<OutElem>
>
import PredicatePredicate.interface Predicate<in A>A function that decides whether a value of type A satisfies a condition.
When to use
Use when you want a reusable boolean check for A, especially when you plan
to combine checks with
and
/
or
or pass a predicate to arrays
and iterables.
Details
A predicate returns true or false and never throws by itself. It does not
narrow types unless you use Refinement.
Example (Defining a predicate)
import { Predicate } from "effect"
const isPositive: Predicate.Predicate<number> = (n) => n > 0
console.log(isPositive(1))
Type-level utilities for working with
Predicate
types.
When to use
Use when you need to extract input types from predicate signatures while
writing generic helpers over predicate types.
Details
These utilities are type-only, create no runtime values, and the namespace is
erased at runtime.
Example (Extracting predicate input)
import { Predicate } from "effect"
type IsString = Predicate.Predicate<string>
type Input = Predicate.Predicate.In<IsString>
Predicate<import TypesTypes.type NoInfer<A> = [A][A extends any
? 0
: never]
Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>>
): 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 Arr.NonEmptyReadonlyArray = /*unresolved*/ anyNonEmptyReadonlyArray<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone, function (type parameter) InElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InElem, function (type parameter) InErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InErr, function (type parameter) InDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>InDone, function (type parameter) Env in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>Env> =>
const transformPull: <
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env,
OutElem2,
OutErr2,
OutDone2,
Env2,
OutErrX,
EnvX
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
f: (
pull: Pull.Pull<OutElem, OutErr, OutDone>,
scope: Scope.Scope
) => Effect.Effect<
Pull.Pull<OutElem2, OutErr2, OutDone2, Env2>,
OutErrX,
EnvX
>
) => Channel<
OutElem2,
Pull.ExcludeDone<OutErr2> | OutErrX,
OutDone2,
InElem,
InErr,
InDone,
Env | Env2 | EnvX
>
Transforms a Channel by applying a function to its Pull implementation.
Example (Transforming pull behavior)
import { Channel, Effect } from "effect"
// Transform a channel by modifying its pull behavior
const originalChannel = Channel.fromIterable([1, 2, 3])
const transformedChannel = Channel.transformPull(
originalChannel,
(pull, scope) =>
Effect.succeed(
Effect.map(pull, (value) => value * 2)
)
)
// Outputs: 2, 4, 6
transformPull(self: Channel<
Arr.NonEmptyReadonlyArray<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; <…;
}
pull: Pull.Pull<
readonly [OutElem, ...OutElem[]],
OutErr,
OutDone,
never
>
(parameter) pull: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
import EffectEffect.const succeed: <A>(value: A) => Effect<A>Creates an Effect that always succeeds with a given value.
When to use
Use when an effect should complete successfully with a specific value without any errors
or external dependencies.
Example (Creating a successful effect)
import { Effect } from "effect"
// Creating an effect that represents a successful scenario
//
// ┌─── Effect<number, never, never>
// ▼
const success = Effect.succeed(42)
succeed(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>
}
pull: Pull.Pull<
readonly [OutElem, ...OutElem[]],
OutErr,
OutDone,
never
>
(parameter) pull: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
function (local function) loop(arr: readonly [OutElem, ...OutElem[]]): Pull.Pull<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone>loop(arr: Arr.NonEmptyReadonlyArray<OutElem>(parameter) arr: {
0: OutElem;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
concat: { (...items: Array<ConcatArray<OutElem>>): Array<OutElem>; (...items: Array<OutElem | ConcatArray<OutElem>>): Array<OutElem> };
join: (separator?: string) => string;
slice: (start?: number, end?: number) => Array<OutElem>;
indexOf: (searchElement: OutElem, fromIndex?: number) => number;
lastIndexOf: (searchElement: OutElem, fromIndex?: number) => number;
every: { (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => value is S, thisArg?: any): this is readonly S[]; (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any): boolea…;
some: (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => void, thisArg?: any) => void;
map: (callbackfn: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => value is S, thisArg?: any): Array<S>; (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any): Array<OutElem> };
reduce: { (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArray<OutElem>) => OutElem): OutElem; (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArr…;
reduceRight: { (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArray<OutElem>) => OutElem): OutElem; (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArr…;
find: { (predicate: (value: OutElem, index: number, obj: ReadonlyArray<OutElem>) => value is S, thisArg?: any): S | undefined; (predicate: (value: OutElem, index: number, obj: ReadonlyArray<OutElem>) => unknown, thisArg?: any): OutElem | undefin…;
findIndex: (predicate: (value: OutElem, index: number, obj: ReadonlyArray<OutElem>) => unknown, thisArg?: any) => number;
entries: () => ArrayIterator<[number, OutElem]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<OutElem>;
includes: (searchElement: OutElem, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: OutElem, index: number, array: Array<OutElem>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => OutElem | undefined;
findLast: { (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => value is S, thisArg?: any): S | undefined; (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any): OutElem | und…;
findLastIndex: (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any) => number;
toReversed: () => Array<OutElem>;
toSorted: (compareFn?: ((a: OutElem, b: OutElem) => number) | undefined) => Array<OutElem>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<OutElem>): Array<OutElem>; (start: number, deleteCount?: number): Array<OutElem> };
with: (index: number, value: OutElem) => Array<OutElem>;
}
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<import ArrArr.type Arr.NonEmptyReadonlyArray = /*unresolved*/ anyNonEmptyReadonlyArray<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>, function (type parameter) OutErr in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutErr, function (type parameter) OutDone in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutDone> {
const const passes: OutElem[]passes: interface Array<T>Array<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem> = []
for (let let i: numberi = 0; let i: numberi < arr: Arr.NonEmptyReadonlyArray<OutElem>(parameter) arr: {
0: OutElem;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
concat: { (...items: Array<ConcatArray<OutElem>>): Array<OutElem>; (...items: Array<OutElem | ConcatArray<OutElem>>): Array<OutElem> };
join: (separator?: string) => string;
slice: (start?: number, end?: number) => Array<OutElem>;
indexOf: (searchElement: OutElem, fromIndex?: number) => number;
lastIndexOf: (searchElement: OutElem, fromIndex?: number) => number;
every: { (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => value is S, thisArg?: any): this is readonly S[]; (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any): boolea…;
some: (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => void, thisArg?: any) => void;
map: (callbackfn: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => value is S, thisArg?: any): Array<S>; (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any): Array<OutElem> };
reduce: { (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArray<OutElem>) => OutElem): OutElem; (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArr…;
reduceRight: { (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArray<OutElem>) => OutElem): OutElem; (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArr…;
find: { (predicate: (value: OutElem, index: number, obj: ReadonlyArray<OutElem>) => value is S, thisArg?: any): S | undefined; (predicate: (value: OutElem, index: number, obj: ReadonlyArray<OutElem>) => unknown, thisArg?: any): OutElem | undefin…;
findIndex: (predicate: (value: OutElem, index: number, obj: ReadonlyArray<OutElem>) => unknown, thisArg?: any) => number;
entries: () => ArrayIterator<[number, OutElem]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<OutElem>;
includes: (searchElement: OutElem, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: OutElem, index: number, array: Array<OutElem>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => OutElem | undefined;
findLast: { (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => value is S, thisArg?: any): S | undefined; (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any): OutElem | und…;
findLastIndex: (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any) => number;
toReversed: () => Array<OutElem>;
toSorted: (compareFn?: ((a: OutElem, b: OutElem) => number) | undefined) => Array<OutElem>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<OutElem>): Array<OutElem>; (start: number, deleteCount?: number): Array<OutElem> };
with: (index: number, value: OutElem) => Array<OutElem>;
}
let i: numberi++) {
if (predicate: Predicate.Predicate<
Types.NoInfer<OutElem>
>
arr: Arr.NonEmptyReadonlyArray<OutElem>(parameter) arr: {
0: OutElem;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
concat: { (...items: Array<ConcatArray<OutElem>>): Array<OutElem>; (...items: Array<OutElem | ConcatArray<OutElem>>): Array<OutElem> };
join: (separator?: string) => string;
slice: (start?: number, end?: number) => Array<OutElem>;
indexOf: (searchElement: OutElem, fromIndex?: number) => number;
lastIndexOf: (searchElement: OutElem, fromIndex?: number) => number;
every: { (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => value is S, thisArg?: any): this is readonly S[]; (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any): boolea…;
some: (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => void, thisArg?: any) => void;
map: (callbackfn: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => value is S, thisArg?: any): Array<S>; (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any): Array<OutElem> };
reduce: { (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArray<OutElem>) => OutElem): OutElem; (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArr…;
reduceRight: { (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArray<OutElem>) => OutElem): OutElem; (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArr…;
find: { (predicate: (value: OutElem, index: number, obj: ReadonlyArray<OutElem>) => value is S, thisArg?: any): S | undefined; (predicate: (value: OutElem, index: number, obj: ReadonlyArray<OutElem>) => unknown, thisArg?: any): OutElem | undefin…;
findIndex: (predicate: (value: OutElem, index: number, obj: ReadonlyArray<OutElem>) => unknown, thisArg?: any) => number;
entries: () => ArrayIterator<[number, OutElem]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<OutElem>;
includes: (searchElement: OutElem, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: OutElem, index: number, array: Array<OutElem>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => OutElem | undefined;
findLast: { (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => value is S, thisArg?: any): S | undefined; (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any): OutElem | und…;
findLastIndex: (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any) => number;
toReversed: () => Array<OutElem>;
toSorted: (compareFn?: ((a: OutElem, b: OutElem) => number) | undefined) => Array<OutElem>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<OutElem>): Array<OutElem>; (start: number, deleteCount?: number): Array<OutElem> };
with: (index: number, value: OutElem) => Array<OutElem>;
}
let i: numberi] as import TypesTypes.type NoInfer<A> = [A][A extends any
? 0
: never]
Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) OutElem in <OutElem, OutErr, OutDone, InElem, InErr, InDone, Env>(self: Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>, predicate: Predicate.Predicate<Types.NoInfer<OutElem>>): Channel<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone, InElem, InErr, InDone, Env>OutElem>)) {
const passes: OutElem[]passes.Array<OutElem>.push(...items: OutElem[]): numberAppends new elements to the end of an array, and returns the new length of the array.
push(arr: Arr.NonEmptyReadonlyArray<OutElem>(parameter) arr: {
0: OutElem;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
concat: { (...items: Array<ConcatArray<OutElem>>): Array<OutElem>; (...items: Array<OutElem | ConcatArray<OutElem>>): Array<OutElem> };
join: (separator?: string) => string;
slice: (start?: number, end?: number) => Array<OutElem>;
indexOf: (searchElement: OutElem, fromIndex?: number) => number;
lastIndexOf: (searchElement: OutElem, fromIndex?: number) => number;
every: { (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => value is S, thisArg?: any): this is readonly S[]; (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any): boolea…;
some: (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => void, thisArg?: any) => void;
map: (callbackfn: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => value is S, thisArg?: any): Array<S>; (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any): Array<OutElem> };
reduce: { (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArray<OutElem>) => OutElem): OutElem; (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArr…;
reduceRight: { (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArray<OutElem>) => OutElem): OutElem; (callbackfn: (previousValue: OutElem, currentValue: OutElem, currentIndex: number, array: ReadonlyArr…;
find: { (predicate: (value: OutElem, index: number, obj: ReadonlyArray<OutElem>) => value is S, thisArg?: any): S | undefined; (predicate: (value: OutElem, index: number, obj: ReadonlyArray<OutElem>) => unknown, thisArg?: any): OutElem | undefin…;
findIndex: (predicate: (value: OutElem, index: number, obj: ReadonlyArray<OutElem>) => unknown, thisArg?: any) => number;
entries: () => ArrayIterator<[number, OutElem]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<OutElem>;
includes: (searchElement: OutElem, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: OutElem, index: number, array: Array<OutElem>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => OutElem | undefined;
findLast: { (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => value is S, thisArg?: any): S | undefined; (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any): OutElem | und…;
findLastIndex: (predicate: (value: OutElem, index: number, array: ReadonlyArray<OutElem>) => unknown, thisArg?: any) => number;
toReversed: () => Array<OutElem>;
toSorted: (compareFn?: ((a: OutElem, b: OutElem) => number) | undefined) => Array<OutElem>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<OutElem>): Array<OutElem>; (start: number, deleteCount?: number): Array<OutElem> };
with: (index: number, value: OutElem) => Array<OutElem>;
}
let i: numberi])
}
}
return import ArrArr.isReadonlyArrayNonEmpty(const passes: OutElem[]passes)
? import EffectEffect.const succeed: <A>(value: A) => Effect<A>Creates an Effect that always succeeds with a given value.
When to use
Use when an effect should complete successfully with a specific value without any errors
or external dependencies.
Example (Creating a successful effect)
import { Effect } from "effect"
// Creating an effect that represents a successful scenario
//
// ┌─── Effect<number, never, never>
// ▼
const success = Effect.succeed(42)
succeed(const passes: OutElem[]passes)
: 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>
}
pull: Pull.Pull<
readonly [OutElem, ...OutElem[]],
OutErr,
OutDone,
never
>
(parameter) pull: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
function (local function) loop(arr: readonly [OutElem, ...OutElem[]]): Pull.Pull<Arr.NonEmptyReadonlyArray<OutElem>, OutErr, OutDone>loop)
}
))))Referenced by 1 symbols