<S, A, B>(s: S, f: (s: S, a: A) => readonly [S, B]): (
self: Chunk<A>
) => [S, Chunk<B>]
<S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [
S,
Chunk<B>
]Maps over the chunk statefully, producing new elements of type B.
Example (Mapping with accumulated state)
import { Chunk } from "effect"
const chunk = Chunk.make(1, 2, 3, 4, 5)
const [finalState, mapped] = Chunk.mapAccum(chunk, 0, (state, current) => [
state + current, // accumulate sum
state + current // output running sum
])
console.log(finalState) // 15 (final accumulated sum)
console.log(Chunk.toArray(mapped)) // [1, 3, 6, 10, 15] (running sums)
// Building a string with indices
const words = Chunk.make("hello", "world", "effect")
const [count, indexed] = Chunk.mapAccum(words, 0, (index, word) => [
index + 1,
`${index}: ${word}`
])
console.log(count) // 3
console.log(Chunk.toArray(indexed)) // ["0: hello", "1: world", "2: effect"]folding
Source effect/Chunk.ts:17467 lines
export const const mapAccum: {
<S, A, B>(
s: S,
f: (s: S, a: A) => readonly [S, B]
): (self: Chunk<A>) => [S, Chunk<B>]
<S, A, B>(
self: Chunk<A>,
s: S,
f: (s: S, a: A) => readonly [S, B]
): [S, Chunk<B>]
}
Maps over the chunk statefully, producing new elements of type B.
Example (Mapping with accumulated state)
import { Chunk } from "effect"
const chunk = Chunk.make(1, 2, 3, 4, 5)
const [finalState, mapped] = Chunk.mapAccum(chunk, 0, (state, current) => [
state + current, // accumulate sum
state + current // output running sum
])
console.log(finalState) // 15 (final accumulated sum)
console.log(Chunk.toArray(mapped)) // [1, 3, 6, 10, 15] (running sums)
// Building a string with indices
const words = Chunk.make("hello", "world", "effect")
const [count, indexed] = Chunk.mapAccum(words, 0, (index, word) => [
index + 1,
`${index}: ${word}`
])
console.log(count) // 3
console.log(Chunk.toArray(indexed)) // ["0: hello", "1: world", "2: effect"]
mapAccum: {
<function (type parameter) S in <S, A, B>(s: S, f: (s: S, a: A) => readonly [S, B]): (self: Chunk<A>) => [S, Chunk<B>]S, function (type parameter) A in <S, A, B>(s: S, f: (s: S, a: A) => readonly [S, B]): (self: Chunk<A>) => [S, Chunk<B>]A, function (type parameter) B in <S, A, B>(s: S, f: (s: S, a: A) => readonly [S, B]): (self: Chunk<A>) => [S, Chunk<B>]B>(s: Ss: function (type parameter) S in <S, A, B>(s: S, f: (s: S, a: A) => readonly [S, B]): (self: Chunk<A>) => [S, Chunk<B>]S, f: (s: S, a: A) => readonly [S, B]f: (s: Ss: function (type parameter) S in <S, A, B>(s: S, f: (s: S, a: A) => readonly [S, B]): (self: Chunk<A>) => [S, Chunk<B>]S, a: Aa: function (type parameter) A in <S, A, B>(s: S, f: (s: S, a: A) => readonly [S, B]): (self: Chunk<A>) => [S, Chunk<B>]A) => readonly [function (type parameter) S in <S, A, B>(s: S, f: (s: S, a: A) => readonly [S, B]): (self: Chunk<A>) => [S, Chunk<B>]S, function (type parameter) B in <S, A, B>(s: S, f: (s: S, a: A) => readonly [S, B]): (self: Chunk<A>) => [S, Chunk<B>]B]): (self: Chunk<A>(parameter) self: {
length: number;
right: Chunk<A>;
left: Chunk<A>;
backing: Backing<A>;
depth: number;
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;
}
interface Chunk<out A>A Chunk is an immutable, ordered collection optimized for efficient concatenation and access patterns.
Example (Inspecting chunk values)
import { Chunk } from "effect"
const chunk: Chunk.Chunk<number> = Chunk.make(1, 2, 3)
console.log(chunk.length) // 3
console.log(Chunk.toArray(chunk)) // [1, 2, 3]
A namespace containing utility types for Chunk operations.
Example (Working with Chunk utility types)
import type { Chunk } from "effect"
// Extract the element type from a Chunk
declare const chunk: Chunk.Chunk<string>
type ElementType = Chunk.Chunk.Infer<typeof chunk> // string
// Create a preserving non-emptiness
declare const nonEmptyChunk: Chunk.NonEmptyChunk<number>
type WithString = Chunk.Chunk.With<typeof nonEmptyChunk, string> // Chunk.NonEmptyChunk<string>
Chunk<function (type parameter) A in <S, A, B>(s: S, f: (s: S, a: A) => readonly [S, B]): (self: Chunk<A>) => [S, Chunk<B>]A>) => [function (type parameter) S in <S, A, B>(s: S, f: (s: S, a: A) => readonly [S, B]): (self: Chunk<A>) => [S, Chunk<B>]S, interface Chunk<out A>A Chunk is an immutable, ordered collection optimized for efficient concatenation and access patterns.
Example (Inspecting chunk values)
import { Chunk } from "effect"
const chunk: Chunk.Chunk<number> = Chunk.make(1, 2, 3)
console.log(chunk.length) // 3
console.log(Chunk.toArray(chunk)) // [1, 2, 3]
A namespace containing utility types for Chunk operations.
Example (Working with Chunk utility types)
import type { Chunk } from "effect"
// Extract the element type from a Chunk
declare const chunk: Chunk.Chunk<string>
type ElementType = Chunk.Chunk.Infer<typeof chunk> // string
// Create a preserving non-emptiness
declare const nonEmptyChunk: Chunk.NonEmptyChunk<number>
type WithString = Chunk.Chunk.With<typeof nonEmptyChunk, string> // Chunk.NonEmptyChunk<string>
Chunk<function (type parameter) B in <S, A, B>(s: S, f: (s: S, a: A) => readonly [S, B]): (self: Chunk<A>) => [S, Chunk<B>]B>]
<function (type parameter) S in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]S, function (type parameter) A in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]A, function (type parameter) B in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]B>(self: Chunk<A>(parameter) self: {
length: number;
right: Chunk<A>;
left: Chunk<A>;
backing: Backing<A>;
depth: number;
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;
}
interface Chunk<out A>A Chunk is an immutable, ordered collection optimized for efficient concatenation and access patterns.
Example (Inspecting chunk values)
import { Chunk } from "effect"
const chunk: Chunk.Chunk<number> = Chunk.make(1, 2, 3)
console.log(chunk.length) // 3
console.log(Chunk.toArray(chunk)) // [1, 2, 3]
A namespace containing utility types for Chunk operations.
Example (Working with Chunk utility types)
import type { Chunk } from "effect"
// Extract the element type from a Chunk
declare const chunk: Chunk.Chunk<string>
type ElementType = Chunk.Chunk.Infer<typeof chunk> // string
// Create a preserving non-emptiness
declare const nonEmptyChunk: Chunk.NonEmptyChunk<number>
type WithString = Chunk.Chunk.With<typeof nonEmptyChunk, string> // Chunk.NonEmptyChunk<string>
Chunk<function (type parameter) A in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]A>, s: Ss: function (type parameter) S in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]S, f: (s: S, a: A) => readonly [S, B]f: (s: Ss: function (type parameter) S in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]S, a: Aa: function (type parameter) A in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]A) => readonly [function (type parameter) S in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]S, function (type parameter) B in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]B]): [function (type parameter) S in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]S, interface Chunk<out A>A Chunk is an immutable, ordered collection optimized for efficient concatenation and access patterns.
Example (Inspecting chunk values)
import { Chunk } from "effect"
const chunk: Chunk.Chunk<number> = Chunk.make(1, 2, 3)
console.log(chunk.length) // 3
console.log(Chunk.toArray(chunk)) // [1, 2, 3]
A namespace containing utility types for Chunk operations.
Example (Working with Chunk utility types)
import type { Chunk } from "effect"
// Extract the element type from a Chunk
declare const chunk: Chunk.Chunk<string>
type ElementType = Chunk.Chunk.Infer<typeof chunk> // string
// Create a preserving non-emptiness
declare const nonEmptyChunk: Chunk.NonEmptyChunk<number>
type WithString = Chunk.Chunk.With<typeof nonEmptyChunk, string> // Chunk.NonEmptyChunk<string>
Chunk<function (type parameter) B in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]B>]
} = dual<(...args: Array<any>) => any, <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]) => [S, Chunk<B>]>(arity: 3, body: <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]) => [S, Chunk<B>]): ((...args: Array<any>) => any) & (<S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]) => [S, Chunk<B>]) (+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(3, <function (type parameter) S in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]S, function (type parameter) A in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]A, function (type parameter) B in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]B>(self: Chunk<A>(parameter) self: {
length: number;
right: Chunk<A>;
left: Chunk<A>;
backing: Backing<A>;
depth: number;
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;
}
interface Chunk<out A>A Chunk is an immutable, ordered collection optimized for efficient concatenation and access patterns.
Example (Inspecting chunk values)
import { Chunk } from "effect"
const chunk: Chunk.Chunk<number> = Chunk.make(1, 2, 3)
console.log(chunk.length) // 3
console.log(Chunk.toArray(chunk)) // [1, 2, 3]
A namespace containing utility types for Chunk operations.
Example (Working with Chunk utility types)
import type { Chunk } from "effect"
// Extract the element type from a Chunk
declare const chunk: Chunk.Chunk<string>
type ElementType = Chunk.Chunk.Infer<typeof chunk> // string
// Create a preserving non-emptiness
declare const nonEmptyChunk: Chunk.NonEmptyChunk<number>
type WithString = Chunk.Chunk.With<typeof nonEmptyChunk, string> // Chunk.NonEmptyChunk<string>
Chunk<function (type parameter) A in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]A>, s: Ss: function (type parameter) S in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]S, f: (s: S, a: A) => readonly [S, B]f: (s: Ss: function (type parameter) S in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]S, a: Aa: function (type parameter) A in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]A) => readonly [function (type parameter) S in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]S, function (type parameter) B in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]B]): [function (type parameter) S in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]S, interface Chunk<out A>A Chunk is an immutable, ordered collection optimized for efficient concatenation and access patterns.
Example (Inspecting chunk values)
import { Chunk } from "effect"
const chunk: Chunk.Chunk<number> = Chunk.make(1, 2, 3)
console.log(chunk.length) // 3
console.log(Chunk.toArray(chunk)) // [1, 2, 3]
A namespace containing utility types for Chunk operations.
Example (Working with Chunk utility types)
import type { Chunk } from "effect"
// Extract the element type from a Chunk
declare const chunk: Chunk.Chunk<string>
type ElementType = Chunk.Chunk.Infer<typeof chunk> // string
// Create a preserving non-emptiness
declare const nonEmptyChunk: Chunk.NonEmptyChunk<number>
type WithString = Chunk.Chunk.With<typeof nonEmptyChunk, string> // Chunk.NonEmptyChunk<string>
Chunk<function (type parameter) B in <S, A, B>(self: Chunk<A>, s: S, f: (s: S, a: A) => readonly [S, B]): [S, Chunk<B>]B>] => {
const [const s1: anys1, const as: anyas] = import RARA.mapAccum(self: Chunk<A>(parameter) self: {
length: number;
right: Chunk<A>;
left: Chunk<A>;
backing: Backing<A>;
depth: number;
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;
}
s: Ss, f: (s: S, a: A) => readonly [S, B]f)
return [const s1: anys1, const fromArrayUnsafe: <A>(
self: ReadonlyArray<A>
) => Chunk<A>
Wraps an array into a chunk without copying.
When to use
Use when the input array can be shared with the resulting Chunk and avoiding
a copy matters.
Gotchas
Mutating the source array after wrapping can mutate the resulting Chunk.
Example (Creating chunks without copying arrays)
import { Chunk } from "effect"
const array = [1, 2, 3, 4, 5]
const chunk = Chunk.fromArrayUnsafe(array)
console.log(Chunk.toArray(chunk)) // [1, 2, 3, 4, 5]
// Warning: Since this doesn't copy the array, mutations affect the chunk
array[0] = 999
console.log(Chunk.toArray(chunk)) // [999, 2, 3, 4, 5]
fromArrayUnsafe(const as: anyas)]
})