<S, A, B>(
initial: LazyArg<S>,
f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>],
options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined
}
): <E, R>(self: Stream<A, E, R>) => Stream<B, E, R>
<A, E, R, S, B>(
self: Stream<A, E, R>,
initial: LazyArg<S>,
f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>],
options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined
}
): Stream<B, E, R>Maps elements statefully, emitting zero or more outputs per input.
Example (Statefully mapping stream values)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const totals = yield* Stream.make(0, 1, 2, 3, 4, 5, 6).pipe(
Stream.mapAccum(() => 0, (total, n) => {
const next = total + n
return [next, [next]] as const
}),
Stream.runCollect
)
yield* Console.log(totals)
})
Effect.runPromise(program)
// Output: [ 0, 1, 3, 6, 10, 15, 21 ]mapping
Source effect/Stream.ts:742445 lines
export const const mapAccum: {
<S, A, B>(
initial: LazyArg<S>,
f: (
s: S,
a: A
) => readonly [
state: S,
values: ReadonlyArray<B>
],
options?: {
readonly onHalt?:
| ((state: S) => ReadonlyArray<B>)
| undefined
}
): <E, R>(
self: Stream<A, E, R>
) => Stream<B, E, R>
<A, E, R, S, B>(
self: Stream<A, E, R>,
initial: LazyArg<S>,
f: (
s: S,
a: A
) => readonly [
state: S,
values: ReadonlyArray<B>
],
options?: {
readonly onHalt?:
| ((state: S) => ReadonlyArray<B>)
| undefined
}
): Stream<B, E, R>
}
Maps elements statefully, emitting zero or more outputs per input.
Example (Statefully mapping stream values)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const totals = yield* Stream.make(0, 1, 2, 3, 4, 5, 6).pipe(
Stream.mapAccum(() => 0, (total, n) => {
const next = total + n
return [next, [next]] as const
}),
Stream.runCollect
)
yield* Console.log(totals)
})
Effect.runPromise(program)
// Output: [ 0, 1, 3, 6, 10, 15, 21 ]
mapAccum: {
<function (type parameter) S in <S, A, B>(initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): <E, R>(self: Stream<A, E, R>) => Stream<B, E, R>
function (type parameter) A in <S, A, B>(initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): <E, R>(self: Stream<A, E, R>) => Stream<B, E, R>
function (type parameter) B in <S, A, B>(initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): <E, R>(self: Stream<A, E, R>) => Stream<B, E, R>
initial: LazyArg<S>initial: type LazyArg<A> = () => AA zero-argument function that produces a value when invoked.
When to use
Use to type a lazy value provider that should not run until called.
Example (Creating a lazy argument)
import { Function } from "effect"
const constNull: Function.LazyArg<null> = Function.constant(null)
LazyArg<function (type parameter) S in <S, A, B>(initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): <E, R>(self: Stream<A, E, R>) => Stream<B, E, R>
f: (
s: S,
a: A
) => readonly [state: S, values: ReadonlyArray<B>]
s: Ss: function (type parameter) S in <S, A, B>(initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): <E, R>(self: Stream<A, E, R>) => Stream<B, E, R>
a: Aa: function (type parameter) A in <S, A, B>(initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): <E, R>(self: Stream<A, E, R>) => Stream<B, E, R>
Sstate: function (type parameter) S in <S, A, B>(initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): <E, R>(self: Stream<A, E, R>) => Stream<B, E, R>
readonly B[]values: interface ReadonlyArray<T>ReadonlyArray<function (type parameter) B in <S, A, B>(initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): <E, R>(self: Stream<A, E, R>) => Stream<B, E, R>
options: | {
readonly onHalt?:
| ((state: S) => ReadonlyArray<B>)
| undefined
}
| undefined
onHalt?: | ((state: S) => ReadonlyArray<B>)
| undefined
state: Sstate: function (type parameter) S in <S, A, B>(initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): <E, R>(self: Stream<A, E, R>) => Stream<B, E, R>
interface ReadonlyArray<T>ReadonlyArray<function (type parameter) B in <S, A, B>(initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): <E, R>(self: Stream<A, E, R>) => Stream<B, E, R>
function (type parameter) E in <E, R>(self: Stream<A, E, R>): Stream<B, E, R>E, function (type parameter) R in <E, R>(self: Stream<A, E, R>): Stream<B, E, R>R>(self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
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 Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <S, A, B>(initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): <E, R>(self: Stream<A, E, R>) => Stream<B, E, R>
function (type parameter) E in <E, R>(self: Stream<A, E, R>): Stream<B, E, R>E, function (type parameter) R in <E, R>(self: Stream<A, E, R>): Stream<B, E, R>R>) => interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) B in <S, A, B>(initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): <E, R>(self: Stream<A, E, R>) => Stream<B, E, R>
function (type parameter) E in <E, R>(self: Stream<A, E, R>): Stream<B, E, R>E, function (type parameter) R in <E, R>(self: Stream<A, E, R>): Stream<B, E, R>R>
<function (type parameter) A in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) E in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) R in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) S in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) B in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
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 Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) E in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) R in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
initial: LazyArg<S>initial: type LazyArg<A> = () => AA zero-argument function that produces a value when invoked.
When to use
Use to type a lazy value provider that should not run until called.
Example (Creating a lazy argument)
import { Function } from "effect"
const constNull: Function.LazyArg<null> = Function.constant(null)
LazyArg<function (type parameter) S in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
f: (
s: S,
a: A
) => readonly [state: S, values: ReadonlyArray<B>]
s: Ss: function (type parameter) S in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
a: Aa: function (type parameter) A in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
Sstate: function (type parameter) S in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
readonly B[]values: interface ReadonlyArray<T>ReadonlyArray<function (type parameter) B in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
options: | {
readonly onHalt?:
| ((state: S) => ReadonlyArray<B>)
| undefined
}
| undefined
onHalt?: | ((state: S) => ReadonlyArray<B>)
| undefined
state: Sstate: function (type parameter) S in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
interface ReadonlyArray<T>ReadonlyArray<function (type parameter) B in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) B in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) E in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) R in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
dual<(...args: Array<any>) => any, <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}) => Stream<B, E, R>>(isDataFirst: (args: IArguments) => boolean, body: <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}) => Stream<B, E, R>): ((...args: Array<any>) => any) & (<A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}) => Stream<B, E, R>) (+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((args: IArgumentsargs) => const isStream: (
u: unknown
) => u is Stream<unknown, unknown, unknown>
Checks whether a value is a Stream.
Example (Checking whether a value is a Stream)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const stream = Stream.make(1, 2, 3)
const notStream = { data: [1, 2, 3] }
yield* Console.log(Stream.isStream(stream))
// true
yield* Console.log(Stream.isStream(notStream))
// false
})
Effect.runPromise(program)
isStream(args: IArgumentsargs[0]), <function (type parameter) A in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) E in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) R in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) S in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) B in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
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 Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) A in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) E in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) R in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
initial: LazyArg<S>initial: type LazyArg<A> = () => AA zero-argument function that produces a value when invoked.
When to use
Use to type a lazy value provider that should not run until called.
Example (Creating a lazy argument)
import { Function } from "effect"
const constNull: Function.LazyArg<null> = Function.constant(null)
LazyArg<function (type parameter) S in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
f: (
s: S,
a: A
) => readonly [state: S, values: ReadonlyArray<B>]
s: Ss: function (type parameter) S in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
a: Aa: function (type parameter) A in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
Sstate: function (type parameter) S in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
readonly B[]values: interface ReadonlyArray<T>ReadonlyArray<function (type parameter) B in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
options: | {
readonly onHalt?:
| ((state: S) => ReadonlyArray<B>)
| undefined
}
| undefined
onHalt?: | ((state: S) => ReadonlyArray<B>)
| undefined
state: Sstate: function (type parameter) S in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
interface ReadonlyArray<T>ReadonlyArray<function (type parameter) B in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
interface Stream<out A, out E = never, out R = never>A Stream<A, E, R> describes a program that can emit many A values, fail
with E, and require R.
Details
Streams are pull-based with backpressure and emit chunks to amortize effect
evaluation. They support monadic composition and error handling similar to
Effect, adapted for multiple values.
Example (Creating and consuming streams)
import { Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
yield* Stream.make(1, 2, 3).pipe(
Stream.map((n) => n * 2),
Stream.runForEach((n) => Console.log(n))
)
})
Effect.runPromise(program)
// Output:
// 2
// 4
// 6
Stream<function (type parameter) B in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) E in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
function (type parameter) R in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
const fromChannel: <
Arr extends Arr.NonEmptyReadonlyArray<any>,
E,
R
>(
channel: Channel.Channel<
Arr,
E,
void,
unknown,
unknown,
unknown,
R
>
) => Stream<
Arr extends Arr.NonEmptyReadonlyArray<infer A>
? A
: never,
E,
R
>
Creates a stream from a array-emitting Channel.
Example (Creating a stream from an array-emitting channel)
import { Channel, Console, Effect, Stream } from "effect"
const program = Effect.gen(function*() {
const channel = Channel.succeed([1, 2, 3] as const)
const stream = Stream.fromChannel(channel)
const result = yield* Stream.runCollect(stream)
yield* Console.log(result)
})
// Output: [ 1, 2, 3 ]
fromChannel(import ChannelChannel.const mapAccum: {
<S, OutElem, B, E = never, R = never>(
initial: LazyArg<S>,
f: (
s: S,
a: Types.NoInfer<OutElem>
) =>
| Effect.Effect<
readonly [
state: S,
values: ReadonlyArray<B>
],
E,
R
>
| readonly [
state: S,
values: ReadonlyArray<B>
],
options?: {
readonly onHalt?:
| ((state: S) => Array<B>)
| undefined
}
): <
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>
) => Channel<
B,
OutErr | E,
OutDone,
InElem,
InErr,
InDone,
Env | R
>
<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env,
S,
B,
E = never,
R = never
>(
self: Channel<
OutElem,
OutErr,
OutDone,
InElem,
InErr,
InDone,
Env
>,
initial: LazyArg<S>,
f: (
s: S,
a: Types.NoInfer<OutElem>
) =>
| Effect.Effect<
readonly [
state: S,
values: ReadonlyArray<B>
],
E,
R
>
| readonly [
state: S,
values: ReadonlyArray<B>
],
options?: {
readonly onHalt?:
| ((state: S) => Array<B>)
| undefined
}
): Channel<
B,
OutErr | E,
OutDone,
InElem,
InErr,
InDone,
Env | R
>
}
self: Stream<A, E, R>(parameter) self: {
channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>;
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; <…;
}
Stream<A, E, R>.channel: Channel.Channel<Arr.NonEmptyReadonlyArray<A>, E, void, unknown, unknown, unknown, R>(property) Stream<A, E, R>.channel: {
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; <…;
}
initial: LazyArg<S>initial,
(state: Sstate, arr: readonly [A, ...A[]](parameter) arr: {
0: A;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
concat: { (...items: Array<ConcatArray<A>>): Array<A>; (...items: Array<A | ConcatArray<A>>): Array<A> };
join: (separator?: string) => string;
slice: (start?: number, end?: number) => Array<A>;
indexOf: (searchElement: A, fromIndex?: number) => number;
lastIndexOf: (searchElement: A, fromIndex?: number) => number;
every: { (predicate: (value: A, index: number, array: ReadonlyArray<A>) => value is S, thisArg?: any): this is readonly S[]; (predicate: (value: A, index: number, array: ReadonlyArray<A>) => unknown, thisArg?: any): boolean };
some: (predicate: (value: A, index: number, array: ReadonlyArray<A>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: A, index: number, array: ReadonlyArray<A>) => void, thisArg?: any) => void;
map: (callbackfn: (value: A, index: number, array: ReadonlyArray<A>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: A, index: number, array: ReadonlyArray<A>) => value is S, thisArg?: any): Array<S>; (predicate: (value: A, index: number, array: ReadonlyArray<A>) => unknown, thisArg?: any): Array<A> };
reduce: { (callbackfn: (previousValue: A, currentValue: A, currentIndex: number, array: ReadonlyArray<A>) => A): A; (callbackfn: (previousValue: A, currentValue: A, currentIndex: number, array: ReadonlyArray<A>) => A, initialValue: A): A; (callbac…;
reduceRight: { (callbackfn: (previousValue: A, currentValue: A, currentIndex: number, array: ReadonlyArray<A>) => A): A; (callbackfn: (previousValue: A, currentValue: A, currentIndex: number, array: ReadonlyArray<A>) => A, initialValue: A): A; (callbac…;
find: { (predicate: (value: A, index: number, obj: ReadonlyArray<A>) => value is S, thisArg?: any): S | undefined; (predicate: (value: A, index: number, obj: ReadonlyArray<A>) => unknown, thisArg?: any): A | undefined };
findIndex: (predicate: (value: A, index: number, obj: ReadonlyArray<A>) => unknown, thisArg?: any) => number;
entries: () => ArrayIterator<[number, A]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<A>;
includes: (searchElement: A, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: A, index: number, array: Array<A>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => A | undefined;
findLast: { (predicate: (value: A, index: number, array: ReadonlyArray<A>) => value is S, thisArg?: any): S | undefined; (predicate: (value: A, index: number, array: ReadonlyArray<A>) => unknown, thisArg?: any): A | undefined };
findLastIndex: (predicate: (value: A, index: number, array: ReadonlyArray<A>) => unknown, thisArg?: any) => number;
toReversed: () => Array<A>;
toSorted: (compareFn?: ((a: A, b: A) => number) | undefined) => Array<A>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<A>): Array<A>; (start: number, deleteCount?: number): Array<A> };
with: (index: number, value: A) => Array<A>;
}
const acc: B[]acc = import ArrArr.const empty: <B>() => B[]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) B in <A, E, R, S, B>(self: Stream<A, E, R>, initial: LazyArg<S>, f: (s: S, a: A) => readonly [state: S, values: ReadonlyArray<B>], options?: {
readonly onHalt?: ((state: S) => ReadonlyArray<B>) | undefined;
}): Stream<B, E, R>
let index: numberindex = 0; let index: numberindex < arr: readonly [A, ...A[]](parameter) arr: {
0: A;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
concat: { (...items: Array<ConcatArray<A>>): Array<A>; (...items: Array<A | ConcatArray<A>>): Array<A> };
join: (separator?: string) => string;
slice: (start?: number, end?: number) => Array<A>;
indexOf: (searchElement: A, fromIndex?: number) => number;
lastIndexOf: (searchElement: A, fromIndex?: number) => number;
every: { (predicate: (value: A, index: number, array: ReadonlyArray<A>) => value is S, thisArg?: any): this is readonly S[]; (predicate: (value: A, index: number, array: ReadonlyArray<A>) => unknown, thisArg?: any): boolean };
some: (predicate: (value: A, index: number, array: ReadonlyArray<A>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: A, index: number, array: ReadonlyArray<A>) => void, thisArg?: any) => void;
map: (callbackfn: (value: A, index: number, array: ReadonlyArray<A>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: A, index: number, array: ReadonlyArray<A>) => value is S, thisArg?: any): Array<S>; (predicate: (value: A, index: number, array: ReadonlyArray<A>) => unknown, thisArg?: any): Array<A> };
reduce: { (callbackfn: (previousValue: A, currentValue: A, currentIndex: number, array: ReadonlyArray<A>) => A): A; (callbackfn: (previousValue: A, currentValue: A, currentIndex: number, array: ReadonlyArray<A>) => A, initialValue: A): A; (callbac…;
reduceRight: { (callbackfn: (previousValue: A, currentValue: A, currentIndex: number, array: ReadonlyArray<A>) => A): A; (callbackfn: (previousValue: A, currentValue: A, currentIndex: number, array: ReadonlyArray<A>) => A, initialValue: A): A; (callbac…;
find: { (predicate: (value: A, index: number, obj: ReadonlyArray<A>) => value is S, thisArg?: any): S | undefined; (predicate: (value: A, index: number, obj: ReadonlyArray<A>) => unknown, thisArg?: any): A | undefined };
findIndex: (predicate: (value: A, index: number, obj: ReadonlyArray<A>) => unknown, thisArg?: any) => number;
entries: () => ArrayIterator<[number, A]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<A>;
includes: (searchElement: A, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: A, index: number, array: Array<A>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => A | undefined;
findLast: { (predicate: (value: A, index: number, array: ReadonlyArray<A>) => value is S, thisArg?: any): S | undefined; (predicate: (value: A, index: number, array: ReadonlyArray<A>) => unknown, thisArg?: any): A | undefined };
findLastIndex: (predicate: (value: A, index: number, array: ReadonlyArray<A>) => unknown, thisArg?: any) => number;
toReversed: () => Array<A>;
toSorted: (compareFn?: ((a: A, b: A) => number) | undefined) => Array<A>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<A>): Array<A>; (start: number, deleteCount?: number): Array<A> };
with: (index: number, value: A) => Array<A>;
}
length: numberlength; let index: numberindex++) {
const [const newState: SnewState, const values: readonly B[]values] = f: (
s: S,
a: A
) => readonly [state: S, values: ReadonlyArray<B>]
state: Sstate, arr: readonly [A, ...A[]](parameter) arr: {
0: A;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
concat: { (...items: Array<ConcatArray<A>>): Array<A>; (...items: Array<A | ConcatArray<A>>): Array<A> };
join: (separator?: string) => string;
slice: (start?: number, end?: number) => Array<A>;
indexOf: (searchElement: A, fromIndex?: number) => number;
lastIndexOf: (searchElement: A, fromIndex?: number) => number;
every: { (predicate: (value: A, index: number, array: ReadonlyArray<A>) => value is S, thisArg?: any): this is readonly S[]; (predicate: (value: A, index: number, array: ReadonlyArray<A>) => unknown, thisArg?: any): boolean };
some: (predicate: (value: A, index: number, array: ReadonlyArray<A>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: A, index: number, array: ReadonlyArray<A>) => void, thisArg?: any) => void;
map: (callbackfn: (value: A, index: number, array: ReadonlyArray<A>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: A, index: number, array: ReadonlyArray<A>) => value is S, thisArg?: any): Array<S>; (predicate: (value: A, index: number, array: ReadonlyArray<A>) => unknown, thisArg?: any): Array<A> };
reduce: { (callbackfn: (previousValue: A, currentValue: A, currentIndex: number, array: ReadonlyArray<A>) => A): A; (callbackfn: (previousValue: A, currentValue: A, currentIndex: number, array: ReadonlyArray<A>) => A, initialValue: A): A; (callbac…;
reduceRight: { (callbackfn: (previousValue: A, currentValue: A, currentIndex: number, array: ReadonlyArray<A>) => A): A; (callbackfn: (previousValue: A, currentValue: A, currentIndex: number, array: ReadonlyArray<A>) => A, initialValue: A): A; (callbac…;
find: { (predicate: (value: A, index: number, obj: ReadonlyArray<A>) => value is S, thisArg?: any): S | undefined; (predicate: (value: A, index: number, obj: ReadonlyArray<A>) => unknown, thisArg?: any): A | undefined };
findIndex: (predicate: (value: A, index: number, obj: ReadonlyArray<A>) => unknown, thisArg?: any) => number;
entries: () => ArrayIterator<[number, A]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<A>;
includes: (searchElement: A, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: A, index: number, array: Array<A>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => A | undefined;
findLast: { (predicate: (value: A, index: number, array: ReadonlyArray<A>) => value is S, thisArg?: any): S | undefined; (predicate: (value: A, index: number, array: ReadonlyArray<A>) => unknown, thisArg?: any): A | undefined };
findLastIndex: (predicate: (value: A, index: number, array: ReadonlyArray<A>) => unknown, thisArg?: any) => number;
toReversed: () => Array<A>;
toSorted: (compareFn?: ((a: A, b: A) => number) | undefined) => Array<A>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<A>): Array<A>; (start: number, deleteCount?: number): Array<A> };
with: (index: number, value: A) => Array<A>;
}
let index: numberindex])
state: Sstate = const newState: SnewState
const acc: B[]acc.Array<B>.push(...items: B[]): numberAppends new elements to the end of an array, and returns the new length of the array.
push(...const values: readonly B[]values)
}
return [state: Sstate, import ArrArr.const isArrayNonEmpty: <A>(
self: Array<A>
) => self is NonEmptyArray<A>
Checks whether a mutable Array is non-empty, narrowing the type to
NonEmptyArray.
When to use
Use when you need the narrowed value to remain a mutable Array after proving
it has at least one element.
Example (Checking for a non-empty array)
import { Array } from "effect"
console.log(Array.isArrayNonEmpty([])) // false
console.log(Array.isArrayNonEmpty([1, 2, 3])) // true
isArrayNonEmpty(const acc: B[]acc) ? import ArrArr.const of: <A>(a: A) => NonEmptyArray<A>Wraps a single value in a NonEmptyArray.
Example (Creating a single-element array)
import { Array } from "effect"
console.log(Array.of(1)) // [1]
of(const acc: [B, ...B[]]const acc: {
0: B;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
pop: () => B | undefined;
push: (...items: Array<B>) => number;
concat: { (...items: Array<ConcatArray<B>>): Array<B>; (...items: Array<B | ConcatArray<B>>): Array<B> };
join: (separator?: string) => string;
reverse: () => Array<B>;
shift: () => B | undefined;
slice: (start?: number, end?: number) => Array<B>;
sort: (compareFn?: ((a: B, b: B) => number) | undefined) => [B, ...B[]];
splice: { (start: number, deleteCount?: number): Array<B>; (start: number, deleteCount: number, ...items: Array<B>): Array<B> };
unshift: (...items: Array<B>) => number;
indexOf: (searchElement: B, fromIndex?: number) => number;
lastIndexOf: (searchElement: B, fromIndex?: number) => number;
every: { (predicate: (value: B, index: number, array: Array<B>) => value is S, thisArg?: any): this is S[]; (predicate: (value: B, index: number, array: Array<B>) => unknown, thisArg?: any): boolean };
some: (predicate: (value: B, index: number, array: Array<B>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: B, index: number, array: Array<B>) => void, thisArg?: any) => void;
map: (callbackfn: (value: B, index: number, array: Array<B>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: B, index: number, array: Array<B>) => value is S, thisArg?: any): Array<S>; (predicate: (value: B, index: number, array: Array<B>) => unknown, thisArg?: any): Array<B> };
reduce: { (callbackfn: (previousValue: B, currentValue: B, currentIndex: number, array: Array<B>) => B): B; (callbackfn: (previousValue: B, currentValue: B, currentIndex: number, array: Array<B>) => B, initialValue: B): B; (callbackfn: (previousVa…;
reduceRight: { (callbackfn: (previousValue: B, currentValue: B, currentIndex: number, array: Array<B>) => B): B; (callbackfn: (previousValue: B, currentValue: B, currentIndex: number, array: Array<B>) => B, initialValue: B): B; (callbackfn: (previousVa…;
find: { (predicate: (value: B, index: number, obj: Array<B>) => value is S, thisArg?: any): S | undefined; (predicate: (value: B, index: number, obj: Array<B>) => unknown, thisArg?: any): B | undefined };
findIndex: (predicate: (value: B, index: number, obj: Array<B>) => unknown, thisArg?: any) => number;
fill: (value: B, start?: number, end?: number) => [B, ...B[]];
copyWithin: (target: number, start: number, end?: number) => [B, ...B[]];
entries: () => ArrayIterator<[number, B]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<B>;
includes: (searchElement: B, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: B, index: number, array: Array<B>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => B | undefined;
findLast: { (predicate: (value: B, index: number, array: Array<B>) => value is S, thisArg?: any): S | undefined; (predicate: (value: B, index: number, array: Array<B>) => unknown, thisArg?: any): B | undefined };
findLastIndex: (predicate: (value: B, index: number, array: Array<B>) => unknown, thisArg?: any) => number;
toReversed: () => Array<B>;
toSorted: (compareFn?: ((a: B, b: B) => number) | undefined) => Array<B>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<B>): Array<B>; (start: number, deleteCount?: number): Array<B> };
with: (index: number, value: B) => Array<B>;
}
const emptyArr: never[]emptyArr]
},
options: | {
readonly onHalt?:
| ((state: S) => ReadonlyArray<B>)
| undefined
}
| undefined
onHalt?: | ((state: S) => ReadonlyArray<B>)
| undefined
onHalt?: | ((state: S) => (readonly [B, ...B[]])[])
| undefined
state: Sstate) {
const const arr: readonly B[]arr = options: {
readonly onHalt?:
| ((state: S) => ReadonlyArray<B>)
| undefined
}
onHalt?: | ((state: S) => ReadonlyArray<B>)
| undefined
state: Sstate)
return import ArrArr.const isReadonlyArrayNonEmpty: <A>(
self: ReadonlyArray<A>
) => self is NonEmptyReadonlyArray<A>
Checks whether a ReadonlyArray is non-empty, narrowing the type to
NonEmptyReadonlyArray.
When to use
Use when you need to prove a readonly array has at least one element without
requiring mutable array methods afterward.
Example (Checking for a non-empty readonly array)
import { Array } from "effect"
console.log(Array.isReadonlyArrayNonEmpty([])) // false
console.log(Array.isReadonlyArrayNonEmpty([1, 2, 3])) // true
isReadonlyArrayNonEmpty(const arr: readonly B[]arr) ? import ArrArr.const of: <A>(a: A) => NonEmptyArray<A>Wraps a single value in a NonEmptyArray.
Example (Creating a single-element array)
import { Array } from "effect"
console.log(Array.of(1)) // [1]
of(const arr: readonly [B, ...B[]]const arr: {
0: B;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
concat: { (...items: Array<ConcatArray<B>>): Array<B>; (...items: Array<B | ConcatArray<B>>): Array<B> };
join: (separator?: string) => string;
slice: (start?: number, end?: number) => Array<B>;
indexOf: (searchElement: B, fromIndex?: number) => number;
lastIndexOf: (searchElement: B, fromIndex?: number) => number;
every: { (predicate: (value: B, index: number, array: ReadonlyArray<B>) => value is S, thisArg?: any): this is readonly S[]; (predicate: (value: B, index: number, array: ReadonlyArray<B>) => unknown, thisArg?: any): boolean };
some: (predicate: (value: B, index: number, array: ReadonlyArray<B>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: B, index: number, array: ReadonlyArray<B>) => void, thisArg?: any) => void;
map: (callbackfn: (value: B, index: number, array: ReadonlyArray<B>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: B, index: number, array: ReadonlyArray<B>) => value is S, thisArg?: any): Array<S>; (predicate: (value: B, index: number, array: ReadonlyArray<B>) => unknown, thisArg?: any): Array<B> };
reduce: { (callbackfn: (previousValue: B, currentValue: B, currentIndex: number, array: ReadonlyArray<B>) => B): B; (callbackfn: (previousValue: B, currentValue: B, currentIndex: number, array: ReadonlyArray<B>) => B, initialValue: B): B; (callbac…;
reduceRight: { (callbackfn: (previousValue: B, currentValue: B, currentIndex: number, array: ReadonlyArray<B>) => B): B; (callbackfn: (previousValue: B, currentValue: B, currentIndex: number, array: ReadonlyArray<B>) => B, initialValue: B): B; (callbac…;
find: { (predicate: (value: B, index: number, obj: ReadonlyArray<B>) => value is S, thisArg?: any): S | undefined; (predicate: (value: B, index: number, obj: ReadonlyArray<B>) => unknown, thisArg?: any): B | undefined };
findIndex: (predicate: (value: B, index: number, obj: ReadonlyArray<B>) => unknown, thisArg?: any) => number;
entries: () => ArrayIterator<[number, B]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<B>;
includes: (searchElement: B, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: B, index: number, array: Array<B>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => B | undefined;
findLast: { (predicate: (value: B, index: number, array: ReadonlyArray<B>) => value is S, thisArg?: any): S | undefined; (predicate: (value: B, index: number, array: ReadonlyArray<B>) => unknown, thisArg?: any): B | undefined };
findLastIndex: (predicate: (value: B, index: number, array: ReadonlyArray<B>) => unknown, thisArg?: any) => number;
toReversed: () => Array<B>;
toSorted: (compareFn?: ((a: B, b: B) => number) | undefined) => Array<B>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<B>): Array<B>; (start: number, deleteCount?: number): Array<B> };
with: (index: number, value: B) => Array<B>;
}
const emptyArr: never[]emptyArr
}
} :
var undefinedundefined
)))