<A, B extends A>(refinement: (a: NoInfer<A>, i: number) => a is B): (
self: Iterable<A>
) => [init: Array<B>, rest: Array<Exclude<A, B>>]
<A>(predicate: (a: NoInfer<A>, i: number) => boolean): (
self: Iterable<A>
) => [init: Array<A>, rest: Array<A>]
<A, B extends A>(
self: Iterable<A>,
refinement: (a: A, i: number) => a is B
): [init: Array<B>, rest: Array<Exclude<A, B>>]
<A>(self: Iterable<A>, predicate: (a: A, i: number) => boolean): [
init: Array<A>,
rest: Array<A>
]Splits an iterable into two arrays: the longest prefix where the predicate holds, and the remaining elements.
When to use
Use when you need both the longest predicate-matching prefix and the remaining elements.
Details
Equivalent to [takeWhile(pred), dropWhile(pred)], but more efficient
because it runs in a single pass. Supports refinements for type narrowing of
the prefix.
Example (Splitting at predicate boundary)
import { Array } from "effect"
console.log(Array.span([1, 3, 2, 4, 5], (x) => x % 2 === 1)) // [[1, 3], [2, 4, 5]]Source effect/Array.ts:146217 lines
export const const span: {
<A, B extends A>(
refinement: (
a: NoInfer<A>,
i: number
) => a is B
): (
self: Iterable<A>
) => [
init: Array<B>,
rest: Array<Exclude<A, B>>
]
<A>(
predicate: (
a: NoInfer<A>,
i: number
) => boolean
): (
self: Iterable<A>
) => [init: Array<A>, rest: Array<A>]
<A, B extends A>(
self: Iterable<A>,
refinement: (a: A, i: number) => a is B
): [init: Array<B>, rest: Array<Exclude<A, B>>]
<A>(
self: Iterable<A>,
predicate: (a: A, i: number) => boolean
): [init: Array<A>, rest: Array<A>]
}
Splits an iterable into two arrays: the longest prefix where the predicate
holds, and the remaining elements.
When to use
Use when you need both the longest predicate-matching prefix and the
remaining elements.
Details
Equivalent to [takeWhile(pred), dropWhile(pred)], but more efficient
because it runs in a single pass. Supports refinements for type narrowing of
the prefix.
Example (Splitting at predicate boundary)
import { Array } from "effect"
console.log(Array.span([1, 3, 2, 4, 5], (x) => x % 2 === 1)) // [[1, 3], [2, 4, 5]]
span: {
<function (type parameter) A in <A, B extends A>(refinement: (a: NoInfer<A>, i: number) => a is B): (self: Iterable<A>) => [init: Array<B>, rest: Array<Exclude<A, B>>]A, function (type parameter) B in <A, B extends A>(refinement: (a: NoInfer<A>, i: number) => a is B): (self: Iterable<A>) => [init: Array<B>, rest: Array<Exclude<A, B>>]B extends function (type parameter) A in <A, B extends A>(refinement: (a: NoInfer<A>, i: number) => a is B): (self: Iterable<A>) => [init: Array<B>, rest: Array<Exclude<A, B>>]A>(
refinement: (a: NoInfer<A>, i: number) => a is Brefinement: (a: NoInfer<A>a: type NoInfer<A> = [A][A extends any ? 0 : never]Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) A in <A, B extends A>(refinement: (a: NoInfer<A>, i: number) => a is B): (self: Iterable<A>) => [init: Array<B>, rest: Array<Exclude<A, B>>]A>, i: numberi: number) => a: NoInfer<A>a is function (type parameter) B in <A, B extends A>(refinement: (a: NoInfer<A>, i: number) => a is B): (self: Iterable<A>) => [init: Array<B>, rest: Array<Exclude<A, B>>]B
): (self: Iterable<A>self: interface Iterable<T, TReturn = any, TNext = any>Iterable<function (type parameter) A in <A, B extends A>(refinement: (a: NoInfer<A>, i: number) => a is B): (self: Iterable<A>) => [init: Array<B>, rest: Array<Exclude<A, B>>]A>) => [B[]init: interface Array<T>Array<function (type parameter) B in <A, B extends A>(refinement: (a: NoInfer<A>, i: number) => a is B): (self: Iterable<A>) => [init: Array<B>, rest: Array<Exclude<A, B>>]B>, Exclude < A, B > []rest: interface Array<T>Array<type Exclude<T, U> = T extends U
? never
: T
Exclude from T those types that are assignable to U
Exclude<function (type parameter) A in <A, B extends A>(refinement: (a: NoInfer<A>, i: number) => a is B): (self: Iterable<A>) => [init: Array<B>, rest: Array<Exclude<A, B>>]A, function (type parameter) B in <A, B extends A>(refinement: (a: NoInfer<A>, i: number) => a is B): (self: Iterable<A>) => [init: Array<B>, rest: Array<Exclude<A, B>>]B>>]
<function (type parameter) A in <A>(predicate: (a: NoInfer<A>, i: number) => boolean): (self: Iterable<A>) => [init: Array<A>, rest: Array<A>]A>(predicate: (a: NoInfer<A>, i: number) => booleanpredicate: (a: NoInfer<A>a: type NoInfer<A> = [A][A extends any ? 0 : never]Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) A in <A>(predicate: (a: NoInfer<A>, i: number) => boolean): (self: Iterable<A>) => [init: Array<A>, rest: Array<A>]A>, i: numberi: number) => boolean): (self: Iterable<A>self: interface Iterable<T, TReturn = any, TNext = any>Iterable<function (type parameter) A in <A>(predicate: (a: NoInfer<A>, i: number) => boolean): (self: Iterable<A>) => [init: Array<A>, rest: Array<A>]A>) => [A[]init: interface Array<T>Array<function (type parameter) A in <A>(predicate: (a: NoInfer<A>, i: number) => boolean): (self: Iterable<A>) => [init: Array<A>, rest: Array<A>]A>, A[]rest: interface Array<T>Array<function (type parameter) A in <A>(predicate: (a: NoInfer<A>, i: number) => boolean): (self: Iterable<A>) => [init: Array<A>, rest: Array<A>]A>]
<function (type parameter) A in <A, B extends A>(self: Iterable<A>, refinement: (a: A, i: number) => a is B): [init: Array<B>, rest: Array<Exclude<A, B>>]A, function (type parameter) B in <A, B extends A>(self: Iterable<A>, refinement: (a: A, i: number) => a is B): [init: Array<B>, rest: Array<Exclude<A, B>>]B extends function (type parameter) A in <A, B extends A>(self: Iterable<A>, refinement: (a: A, i: number) => a is B): [init: Array<B>, rest: Array<Exclude<A, B>>]A>(
self: Iterable<A>self: interface Iterable<T, TReturn = any, TNext = any>Iterable<function (type parameter) A in <A, B extends A>(self: Iterable<A>, refinement: (a: A, i: number) => a is B): [init: Array<B>, rest: Array<Exclude<A, B>>]A>,
refinement: (a: A, i: number) => a is Brefinement: (a: Aa: function (type parameter) A in <A, B extends A>(self: Iterable<A>, refinement: (a: A, i: number) => a is B): [init: Array<B>, rest: Array<Exclude<A, B>>]A, i: numberi: number) => a: Aa is function (type parameter) B in <A, B extends A>(self: Iterable<A>, refinement: (a: A, i: number) => a is B): [init: Array<B>, rest: Array<Exclude<A, B>>]B
): [B[]init: interface Array<T>Array<function (type parameter) B in <A, B extends A>(self: Iterable<A>, refinement: (a: A, i: number) => a is B): [init: Array<B>, rest: Array<Exclude<A, B>>]B>, Exclude < A, B > []rest: interface Array<T>Array<type Exclude<T, U> = T extends U
? never
: T
Exclude from T those types that are assignable to U
Exclude<function (type parameter) A in <A, B extends A>(self: Iterable<A>, refinement: (a: A, i: number) => a is B): [init: Array<B>, rest: Array<Exclude<A, B>>]A, function (type parameter) B in <A, B extends A>(self: Iterable<A>, refinement: (a: A, i: number) => a is B): [init: Array<B>, rest: Array<Exclude<A, B>>]B>>]
<function (type parameter) A in <A>(self: Iterable<A>, predicate: (a: A, i: number) => boolean): [init: Array<A>, rest: Array<A>]A>(self: Iterable<A>self: interface Iterable<T, TReturn = any, TNext = any>Iterable<function (type parameter) A in <A>(self: Iterable<A>, predicate: (a: A, i: number) => boolean): [init: Array<A>, rest: Array<A>]A>, predicate: (a: A, i: number) => booleanpredicate: (a: Aa: function (type parameter) A in <A>(self: Iterable<A>, predicate: (a: A, i: number) => boolean): [init: Array<A>, rest: Array<A>]A, i: numberi: number) => boolean): [A[]init: interface Array<T>Array<function (type parameter) A in <A>(self: Iterable<A>, predicate: (a: A, i: number) => boolean): [init: Array<A>, rest: Array<A>]A>, A[]rest: interface Array<T>Array<function (type parameter) A in <A>(self: Iterable<A>, predicate: (a: A, i: number) => boolean): [init: Array<A>, rest: Array<A>]A>]
} = dual<(...args: Array<any>) => any, <A>(self: Iterable<A>, predicate: (a: A, i: number) => boolean) => [init: Array<A>, rest: Array<A>]>(arity: 2, body: <A>(self: Iterable<A>, predicate: (a: A, i: number) => boolean) => [init: Array<A>, rest: Array<A>]): ((...args: Array<any>) => any) & (<A>(self: Iterable<A>, predicate: (a: A, i: number) => boolean) => [init: Array<A>, rest: Array<A>]) (+1 overload)Creates a function that can be called in data-first style or data-last
(pipe-friendly) style.
When to use
Use to expose one implementation through both direct and pipe-friendly
call styles.
Details
Pass either the arity of the uncurried function or a predicate that decides
whether the current call is data-first. Arity is the common case. Use a
predicate when optional arguments make arity ambiguous.
Example (Selecting data-first or data-last style by arity)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(2, (self, that) => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Defining overloads with call signatures)
import { Function, pipe } from "effect"
const sum: {
(that: number): (self: number) => number
(self: number, that: number): number
} = Function.dual(2, (self: number, that: number): number => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Selecting data-first or data-last style with a predicate)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(
(args) => args.length === 2,
(self, that) => self + that
)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
dual(
2,
<function (type parameter) A in <A>(self: Iterable<A>, predicate: (a: A, i: number) => boolean): [init: Array<A>, rest: Array<A>]A>(self: Iterable<A>self: interface Iterable<T, TReturn = any, TNext = any>Iterable<function (type parameter) A in <A>(self: Iterable<A>, predicate: (a: A, i: number) => boolean): [init: Array<A>, rest: Array<A>]A>, predicate: (a: A, i: number) => booleanpredicate: (a: Aa: function (type parameter) A in <A>(self: Iterable<A>, predicate: (a: A, i: number) => boolean): [init: Array<A>, rest: Array<A>]A, i: numberi: number) => boolean): [A[]init: interface Array<T>Array<function (type parameter) A in <A>(self: Iterable<A>, predicate: (a: A, i: number) => boolean): [init: Array<A>, rest: Array<A>]A>, A[]rest: interface Array<T>Array<function (type parameter) A in <A>(self: Iterable<A>, predicate: (a: A, i: number) => boolean): [init: Array<A>, rest: Array<A>]A>] => {
const const input: A[]input = const fromIterable: <A>(
collection: Iterable<A>
) => A[]
Converts an Iterable to an Array.
When to use
Use to convert any Iterable (Set, Generator, etc.) into an array.
Details
If the input is already an array, this returns it by reference without
copying. Otherwise, it creates a new array from the iterable. Use copy if
you need a fresh array even when the input is already an array.
Example (Converting a Set to an array)
import { Array } from "effect"
const result = Array.fromIterable(new Set([1, 2, 3]))
console.log(result) // [1, 2, 3]
fromIterable(self: Iterable<A>self)
return const splitAt: <A>(self: Iterable<A>, n: number) => [beforeIndex: A[], fromIndex: A[]] (+1 overload)splitAt(const input: A[]input, const spanIndex: <A>(
self: Iterable<A>,
predicate: (a: A, i: number) => boolean
) => number
const input: A[]input, predicate: (a: A, i: number) => booleanpredicate))
}
)Referenced by 1 symbols