<In, Out extends In>(refinement: Refinement<In, Out>): Sink<
Array<Out>,
In,
In
>
<In>(predicate: Predicate<In>): Sink<Array<In>, In, In>Collects the longest input prefix whose elements satisfy the predicate or refinement.
Details
The first failing input is consumed and excluded from the result. Any later elements from the same pulled array are returned as leftovers.
constructors
Source effect/Sink.ts:155723 lines
export const const takeWhile: {
<In, Out extends In>(
refinement: Refinement<In, Out>
): Sink<Array<Out>, In, In>
<In>(predicate: Predicate<In>): Sink<
Array<In>,
In,
In
>
}
Collects the longest input prefix whose elements satisfy the predicate or
refinement.
Details
The first failing input is consumed and excluded from the result. Any later
elements from the same pulled array are returned as leftovers.
takeWhile: {
<function (type parameter) In in <In, Out extends In>(refinement: Refinement<In, Out>): Sink<Array<Out>, In, In>In, function (type parameter) Out in <In, Out extends In>(refinement: Refinement<In, Out>): Sink<Array<Out>, In, In>Out extends function (type parameter) In in <In, Out extends In>(refinement: Refinement<In, Out>): Sink<Array<Out>, In, In>In>(refinement: Refinement<In, Out>refinement: 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) In in <In, Out extends In>(refinement: Refinement<In, Out>): Sink<Array<Out>, In, In>In, function (type parameter) Out in <In, Out extends In>(refinement: Refinement<In, Out>): Sink<Array<Out>, In, In>Out>): interface Sink<out A, in In = unknown, out L = never, out E = never, out R = never>A Sink<A, In, L, E, R> is used to consume elements produced by a Stream.
You can think of a sink as a function that will consume a variable amount of
In elements (could be 0, 1, or many), might fail with an error of type E,
and will eventually yield a value of type A together with a remainder of
type L (i.e. any leftovers).
Example (Running a sink with a stream)
import { Effect, Sink, Stream } from "effect"
// Create a simple sink that always succeeds with a value
const sink: Sink.Sink<number> = Sink.succeed(42)
// Use the sink to consume a stream
const stream = Stream.make(1, 2, 3)
const program = Stream.run(stream, sink)
Effect.runPromise(program).then(console.log)
// Output: 42
Namespace containing types and interfaces for Sink variance and type relationships.
Sink<interface Array<T>Array<function (type parameter) Out in <In, Out extends In>(refinement: Refinement<In, Out>): Sink<Array<Out>, In, In>Out>, function (type parameter) In in <In, Out extends In>(refinement: Refinement<In, Out>): Sink<Array<Out>, In, In>In, function (type parameter) In in <In, Out extends In>(refinement: Refinement<In, Out>): Sink<Array<Out>, In, In>In>
<function (type parameter) In in <In>(predicate: Predicate<In>): Sink<Array<In>, In, In>In>(predicate: Predicate<In>predicate: 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<function (type parameter) In in <In>(predicate: Predicate<In>): Sink<Array<In>, In, In>In>): interface Sink<out A, in In = unknown, out L = never, out E = never, out R = never>A Sink<A, In, L, E, R> is used to consume elements produced by a Stream.
You can think of a sink as a function that will consume a variable amount of
In elements (could be 0, 1, or many), might fail with an error of type E,
and will eventually yield a value of type A together with a remainder of
type L (i.e. any leftovers).
Example (Running a sink with a stream)
import { Effect, Sink, Stream } from "effect"
// Create a simple sink that always succeeds with a value
const sink: Sink.Sink<number> = Sink.succeed(42)
// Use the sink to consume a stream
const stream = Stream.make(1, 2, 3)
const program = Stream.run(stream, sink)
Effect.runPromise(program).then(console.log)
// Output: 42
Namespace containing types and interfaces for Sink variance and type relationships.
Sink<interface Array<T>Array<function (type parameter) In in <In>(predicate: Predicate<In>): Sink<Array<In>, In, In>In>, function (type parameter) In in <In>(predicate: Predicate<In>): Sink<Array<In>, In, In>In, function (type parameter) In in <In>(predicate: Predicate<In>): Sink<Array<In>, In, In>In>
} = <function (type parameter) In in <In>(predicate: Predicate<In>): Sink<Array<In>, In, In>In>(predicate: Predicate<In>predicate: 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<function (type parameter) In in <In>(predicate: Predicate<In>): Sink<Array<In>, In, In>In>): interface Sink<out A, in In = unknown, out L = never, out E = never, out R = never>A Sink<A, In, L, E, R> is used to consume elements produced by a Stream.
You can think of a sink as a function that will consume a variable amount of
In elements (could be 0, 1, or many), might fail with an error of type E,
and will eventually yield a value of type A together with a remainder of
type L (i.e. any leftovers).
Example (Running a sink with a stream)
import { Effect, Sink, Stream } from "effect"
// Create a simple sink that always succeeds with a value
const sink: Sink.Sink<number> = Sink.succeed(42)
// Use the sink to consume a stream
const stream = Stream.make(1, 2, 3)
const program = Stream.run(stream, sink)
Effect.runPromise(program).then(console.log)
// Output: 42
Namespace containing types and interfaces for Sink variance and type relationships.
Sink<interface Array<T>Array<function (type parameter) In in <In>(predicate: Predicate<In>): Sink<Array<In>, In, In>In>, function (type parameter) In in <In>(predicate: Predicate<In>): Sink<Array<In>, In, In>In, function (type parameter) In in <In>(predicate: Predicate<In>): Sink<Array<In>, In, In>In> =>
const fromTransform: <
In,
A,
E,
R,
L = never
>(
transform: (
upstream: Pull.Pull<
NonEmptyReadonlyArray<In>,
never,
void
>,
scope: Scope.Scope
) => Effect.Effect<End<A, L>, E, R>
) => Sink<A, In, L, E, R>
Creates a Sink from a low-level transform function.
Details
The transform receives the upstream pull of non-empty input arrays and the
active scope, and returns an effect that completes with the sink's End
value.
fromTransform((upstream: Pull.Pull<
readonly [In, ...In[]],
never,
void,
never
>
(parameter) upstream: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
const out: In[]out = import ArrArr.const empty: <In>() => In[]Creates an empty array.
When to use
Use to create a typed empty array without allocating placeholder elements.
Example (Creating an empty array)
import { Array } from "effect"
const result = Array.empty<number>()
console.log(result) // []
empty<function (type parameter) In in <In>(predicate: Predicate<In>): Sink<Array<In>, In, In>In>()
return upstream: Pull.Pull<
readonly [In, ...In[]],
never,
void,
never
>
(parameter) upstream: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
Pipeable.pipe<Pull.Pull<readonly [In, ...In[]], never, void, never>, Effect.Effect<void, Cause.Done<void> | Cause.Done<readonly [In[], readonly [In, ...In[]] | undefined]>, never>, Effect.Effect<never, Cause.Done<void> | Cause.Done<readonly [In[], readonly [In, ...In[]] | undefined]>, never>, Effect.Effect<End<In[], In>, never, never>>(this: Pull.Pull<...>, ab: (_: Pull.Pull<readonly [In, ...In[]], never, void, never>) => Effect.Effect<void, Cause.Done<void> | Cause.Done<readonly [In[], readonly [In, ...In[]] | undefined]>, never>, bc: (_: Effect.Effect<...>) => Effect.Effect<...>, cd: (_: Effect.Effect<...>) => Effect.Effect<...>): Effect.Effect<...> (+21 overloads)pipe(
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>
}
arr: readonly [In, ...In[]](parameter) arr: {
0: In;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
concat: { (...items: Array<ConcatArray<In>>): Array<In>; (...items: Array<In | ConcatArray<In>>): Array<In> };
join: (separator?: string) => string;
slice: (start?: number, end?: number) => Array<In>;
indexOf: (searchElement: In, fromIndex?: number) => number;
lastIndexOf: (searchElement: In, fromIndex?: number) => number;
every: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): this is readonly S[]; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): boolean };
some: (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: In, index: number, array: ReadonlyArray<In>) => void, thisArg?: any) => void;
map: (callbackfn: (value: In, index: number, array: ReadonlyArray<In>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): Array<S>; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): Array<In> };
reduce: { (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In): In; (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In, initialValue: In): I…;
reduceRight: { (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In): In; (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In, initialValue: In): I…;
find: { (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => value is S, thisArg?: any): S | undefined; (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => unknown, thisArg?: any): In | undefined };
findIndex: (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => unknown, thisArg?: any) => number;
entries: () => ArrayIterator<[number, In]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<In>;
includes: (searchElement: In, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: In, index: number, array: Array<In>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => In | undefined;
findLast: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): S | undefined; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): In | undefined };
findLastIndex: (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any) => number;
toReversed: () => Array<In>;
toSorted: (compareFn?: ((a: In, b: In) => number) | undefined) => Array<In>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<In>): Array<In>; (start: number, deleteCount?: number): Array<In> };
with: (index: number, value: In) => Array<In>;
}
let i: numberi = 0; let i: numberi < arr: readonly [In, ...In[]](parameter) arr: {
0: In;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
concat: { (...items: Array<ConcatArray<In>>): Array<In>; (...items: Array<In | ConcatArray<In>>): Array<In> };
join: (separator?: string) => string;
slice: (start?: number, end?: number) => Array<In>;
indexOf: (searchElement: In, fromIndex?: number) => number;
lastIndexOf: (searchElement: In, fromIndex?: number) => number;
every: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): this is readonly S[]; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): boolean };
some: (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: In, index: number, array: ReadonlyArray<In>) => void, thisArg?: any) => void;
map: (callbackfn: (value: In, index: number, array: ReadonlyArray<In>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): Array<S>; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): Array<In> };
reduce: { (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In): In; (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In, initialValue: In): I…;
reduceRight: { (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In): In; (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In, initialValue: In): I…;
find: { (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => value is S, thisArg?: any): S | undefined; (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => unknown, thisArg?: any): In | undefined };
findIndex: (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => unknown, thisArg?: any) => number;
entries: () => ArrayIterator<[number, In]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<In>;
includes: (searchElement: In, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: In, index: number, array: Array<In>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => In | undefined;
findLast: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): S | undefined; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): In | undefined };
findLastIndex: (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any) => number;
toReversed: () => Array<In>;
toSorted: (compareFn?: ((a: In, b: In) => number) | undefined) => Array<In>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<In>): Array<In>; (start: number, deleteCount?: number): Array<In> };
with: (index: number, value: In) => Array<In>;
}
length: numberlength; let i: numberi++) {
if (!predicate: Predicate<In>predicate(arr: readonly [In, ...In[]](parameter) arr: {
0: In;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
concat: { (...items: Array<ConcatArray<In>>): Array<In>; (...items: Array<In | ConcatArray<In>>): Array<In> };
join: (separator?: string) => string;
slice: (start?: number, end?: number) => Array<In>;
indexOf: (searchElement: In, fromIndex?: number) => number;
lastIndexOf: (searchElement: In, fromIndex?: number) => number;
every: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): this is readonly S[]; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): boolean };
some: (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: In, index: number, array: ReadonlyArray<In>) => void, thisArg?: any) => void;
map: (callbackfn: (value: In, index: number, array: ReadonlyArray<In>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): Array<S>; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): Array<In> };
reduce: { (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In): In; (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In, initialValue: In): I…;
reduceRight: { (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In): In; (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In, initialValue: In): I…;
find: { (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => value is S, thisArg?: any): S | undefined; (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => unknown, thisArg?: any): In | undefined };
findIndex: (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => unknown, thisArg?: any) => number;
entries: () => ArrayIterator<[number, In]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<In>;
includes: (searchElement: In, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: In, index: number, array: Array<In>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => In | undefined;
findLast: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): S | undefined; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): In | undefined };
findLastIndex: (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any) => number;
toReversed: () => Array<In>;
toSorted: (compareFn?: ((a: In, b: In) => number) | undefined) => Array<In>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<In>): Array<In>; (start: number, deleteCount?: number): Array<In> };
with: (index: number, value: In) => Array<In>;
}
let i: numberi])) {
const const leftover:
| Arr.NonEmptyReadonlyArray<In>
| undefined
import ArrArr.type NonEmptyReadonlyArray<A> = readonly [
A,
...A[]
]
A readonly array guaranteed to have at least one element.
When to use
Use when non-emptiness must be tracked at the type level while preventing mutation.
Many Array module functions accept or return this type.
Example (Typing a non-empty array)
import type { Array } from "effect"
const nonEmpty: Array.NonEmptyReadonlyArray<number> = [1, 2, 3]
const head: number = nonEmpty[0] // guaranteed to exist
NonEmptyReadonlyArray<function (type parameter) In in <In>(predicate: Predicate<In>): Sink<Array<In>, In, In>In> | undefined = (let i: numberi + 1) < arr: readonly [In, ...In[]](parameter) arr: {
0: In;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
concat: { (...items: Array<ConcatArray<In>>): Array<In>; (...items: Array<In | ConcatArray<In>>): Array<In> };
join: (separator?: string) => string;
slice: (start?: number, end?: number) => Array<In>;
indexOf: (searchElement: In, fromIndex?: number) => number;
lastIndexOf: (searchElement: In, fromIndex?: number) => number;
every: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): this is readonly S[]; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): boolean };
some: (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: In, index: number, array: ReadonlyArray<In>) => void, thisArg?: any) => void;
map: (callbackfn: (value: In, index: number, array: ReadonlyArray<In>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): Array<S>; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): Array<In> };
reduce: { (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In): In; (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In, initialValue: In): I…;
reduceRight: { (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In): In; (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In, initialValue: In): I…;
find: { (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => value is S, thisArg?: any): S | undefined; (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => unknown, thisArg?: any): In | undefined };
findIndex: (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => unknown, thisArg?: any) => number;
entries: () => ArrayIterator<[number, In]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<In>;
includes: (searchElement: In, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: In, index: number, array: Array<In>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => In | undefined;
findLast: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): S | undefined; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): In | undefined };
findLastIndex: (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any) => number;
toReversed: () => Array<In>;
toSorted: (compareFn?: ((a: In, b: In) => number) | undefined) => Array<In>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<In>): Array<In>; (start: number, deleteCount?: number): Array<In> };
with: (index: number, value: In) => Array<In>;
}
length: numberlength
? arr: readonly [In, ...In[]](parameter) arr: {
0: In;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
concat: { (...items: Array<ConcatArray<In>>): Array<In>; (...items: Array<In | ConcatArray<In>>): Array<In> };
join: (separator?: string) => string;
slice: (start?: number, end?: number) => Array<In>;
indexOf: (searchElement: In, fromIndex?: number) => number;
lastIndexOf: (searchElement: In, fromIndex?: number) => number;
every: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): this is readonly S[]; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): boolean };
some: (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: In, index: number, array: ReadonlyArray<In>) => void, thisArg?: any) => void;
map: (callbackfn: (value: In, index: number, array: ReadonlyArray<In>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): Array<S>; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): Array<In> };
reduce: { (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In): In; (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In, initialValue: In): I…;
reduceRight: { (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In): In; (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In, initialValue: In): I…;
find: { (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => value is S, thisArg?: any): S | undefined; (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => unknown, thisArg?: any): In | undefined };
findIndex: (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => unknown, thisArg?: any) => number;
entries: () => ArrayIterator<[number, In]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<In>;
includes: (searchElement: In, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: In, index: number, array: Array<In>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => In | undefined;
findLast: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): S | undefined; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): In | undefined };
findLastIndex: (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any) => number;
toReversed: () => Array<In>;
toSorted: (compareFn?: ((a: In, b: In) => number) | undefined) => Array<In>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<In>): Array<In>; (start: number, deleteCount?: number): Array<In> };
with: (index: number, value: In) => Array<In>;
}
ReadonlyArray<In>.slice(start?: number, end?: number): In[]Returns a section of an array.
slice(let i: numberi + 1) as any
: var undefinedundefined
return import CauseCause.const done: <A = void>(
value?: A
) => Effect.Effect<never, Done<A>>
Creates an Effect that fails with a Done error. Shorthand for
Effect.fail(Cause.Done(value)).
When to use
Use when you model stream or queue completion through the error channel.
Example (Failing with Done)
import { Cause, Effect } from "effect"
const program = Cause.done("finished")
Effect.runPromiseExit(program).then((exit) => {
console.log(exit._tag) // "Failure"
})
done([const out: In[]out, const leftover:
| Arr.NonEmptyReadonlyArray<In>
| undefined
type const = readonly [In[], readonly [In, ...In[]] | undefined]const)
}
const out: In[]out.Array<In>.push(...items: In[]): numberAppends new elements to the end of an array, and returns the new length of the array.
push(arr: readonly [In, ...In[]](parameter) arr: {
0: In;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
concat: { (...items: Array<ConcatArray<In>>): Array<In>; (...items: Array<In | ConcatArray<In>>): Array<In> };
join: (separator?: string) => string;
slice: (start?: number, end?: number) => Array<In>;
indexOf: (searchElement: In, fromIndex?: number) => number;
lastIndexOf: (searchElement: In, fromIndex?: number) => number;
every: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): this is readonly S[]; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): boolean };
some: (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: In, index: number, array: ReadonlyArray<In>) => void, thisArg?: any) => void;
map: (callbackfn: (value: In, index: number, array: ReadonlyArray<In>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): Array<S>; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): Array<In> };
reduce: { (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In): In; (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In, initialValue: In): I…;
reduceRight: { (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In): In; (callbackfn: (previousValue: In, currentValue: In, currentIndex: number, array: ReadonlyArray<In>) => In, initialValue: In): I…;
find: { (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => value is S, thisArg?: any): S | undefined; (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => unknown, thisArg?: any): In | undefined };
findIndex: (predicate: (value: In, index: number, obj: ReadonlyArray<In>) => unknown, thisArg?: any) => number;
entries: () => ArrayIterator<[number, In]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<In>;
includes: (searchElement: In, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: In, index: number, array: Array<In>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => In | undefined;
findLast: { (predicate: (value: In, index: number, array: ReadonlyArray<In>) => value is S, thisArg?: any): S | undefined; (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any): In | undefined };
findLastIndex: (predicate: (value: In, index: number, array: ReadonlyArray<In>) => unknown, thisArg?: any) => number;
toReversed: () => Array<In>;
toSorted: (compareFn?: ((a: In, b: In) => number) | undefined) => Array<In>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<In>): Array<In>; (start: number, deleteCount?: number): Array<In> };
with: (index: number, value: In) => Array<In>;
}
let i: numberi])
}
return import EffectEffect.const void: Effect.Effect<void, never, never>(alias) const void: {
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;
}
Returns an effect that succeeds with void.
void
}),
import EffectEffect.const forever: <
Arg extends
| Effect<any, any, any>
| {
readonly disableYield?:
| boolean
| undefined
}
| undefined = {
readonly disableYield?: boolean | undefined
}
>(
effectOrOptions?: Arg,
options?:
| {
readonly disableYield?:
| boolean
| undefined
}
| undefined
) => [Arg] extends [
Effect<infer _A, infer _E, infer _R>
]
? Effect<never, _E, _R>
: <A, E, R>(
self: Effect<A, E, R>
) => Effect<never, E, R>
Repeats this effect forever (until the first error).
Example (Repeating forever)
import { Console, Effect, Fiber } from "effect"
const task = Effect.gen(function*() {
yield* Console.log("Task running...")
yield* Effect.sleep("1 second")
})
// This will run forever, printing every second
const program = task.pipe(Effect.forever)
// This will run forever, without yielding every iteration
const programNoYield = task.pipe(Effect.forever({ disableYield: true }))
// Run for 5 seconds then interrupt
const timedProgram = Effect.gen(function*() {
const fiber = yield* Effect.forkChild(program)
yield* Effect.sleep("5 seconds")
yield* Fiber.interrupt(fiber)
})
forever({ disableYield: truedisableYield: true }),
import PullPull.const catchDone: {
<E, A2, E2, R2>(
f: (
leftover: Cause.Done.Extract<E>
) => Effect<A2, E2, R2>
): <A, R>(
self: Effect<A, E, R>
) => Effect<A | A2, ExcludeDone<E> | E2, R | R2>
<A, R, E, A2, E2, R2>(
self: Effect<A, E, R>,
f: (
leftover: Cause.Done.Extract<E>
) => Effect<A2, E2, R2>
): Effect<A | A2, ExcludeDone<E> | E2, R | R2>
}
end: | void
| readonly [
In[],
readonly [In, ...In[]] | undefined
]
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<type End<A, L = never> = readonly [
value: A,
leftover?: readonly [L, ...L[]] | undefined
]
Tuple returned when a Sink finishes.
Details
The first element is the sink result. The optional second element contains a
non-empty array of leftover input that was pulled but not consumed.
End<interface Array<T>Array<function (type parameter) In in <In>(predicate: Predicate<In>): Sink<Array<In>, In, In>In>, function (type parameter) In in <In>(predicate: Predicate<In>): Sink<Array<In>, In, In>In>>(end: | void
| readonly [
In[],
readonly [In, ...In[]] | undefined
]
const out: In[]out]))
)
})Referenced by 1 symbols