fp-ts
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Functional programming in TypeScript
332 lines (331 loc) • 8.97 kB
TypeScript
/**
* ```ts
* interface Task<A> {
* (): Promise<A>
* }
* ```
*
* `Task<A>` represents an asynchronous computation that yields a value of type `A` and **never fails**.
* If you want to represent an asynchronous computation that may fail, please see `TaskEither`.
*
* @since 2.0.0
*/
import { Applicative1 } from './Applicative'
import { IO } from './IO'
import { Monad1 } from './Monad'
import { MonadTask1 } from './MonadTask'
import { Monoid } from './Monoid'
import { Semigroup } from './Semigroup'
import { Functor1 } from './Functor'
/**
* @category model
* @since 2.0.0
*/
export interface Task<A> {
(): Promise<A>
}
/**
* @category constructors
* @since 2.0.0
*/
export declare const fromIO: <A>(ma: IO<A>) => Task<A>
/**
* Creates a task that will complete after a time delay
*
* @example
* import { sequenceT } from 'fp-ts/Apply'
* import * as T from 'fp-ts/Task'
*
* async function test() {
* const log: Array<string> = []
* const append = (message: string): T.Task<void> =>
* T.fromIO(() => {
* log.push(message)
* })
* const fa = append('a')
* const fb = append('b')
* const fc = T.delay(10)(append('c'))
* const fd = append('d')
* await sequenceT(T.task)(fa, fb, fc, fd)()
* assert.deepStrictEqual(log, ['a', 'b', 'd', 'c'])
* }
*
* test()
*
* @category combinators
* @since 2.0.0
*/
export declare function delay(millis: number): <A>(ma: Task<A>) => Task<A>
/**
* @category combinators
* @since 2.4.0
*/
export declare function fromIOK<A extends ReadonlyArray<unknown>, B>(f: (...a: A) => IO<B>): (...a: A) => Task<B>
/**
* @category combinators
* @since 2.4.0
*/
export declare function chainIOK<A, B>(f: (a: A) => IO<B>): (ma: Task<A>) => Task<B>
/**
* `map` can be used to turn functions `(a: A) => B` into functions `(fa: F<A>) => F<B>` whose argument and return types
* use the type constructor `F` to represent some computational context.
*
* @category Functor
* @since 2.0.0
*/
export declare const map: <A, B>(f: (a: A) => B) => (fa: Task<A>) => Task<B>
/**
* Apply a function to an argument under a type constructor.
*
* @category Apply
* @since 2.0.0
*/
export declare const ap: <A>(fa: Task<A>) => <B>(fab: Task<(a: A) => B>) => Task<B>
/**
* Combine two effectful actions, keeping only the result of the first.
*
* Derivable from `Apply`.
*
* @category combinators
* @since 2.0.0
*/
export declare const apFirst: <B>(fb: Task<B>) => <A>(fa: Task<A>) => Task<A>
/**
* Combine two effectful actions, keeping only the result of the second.
*
* Derivable from `Apply`.
*
* @category combinators
* @since 2.0.0
*/
export declare const apSecond: <B>(fb: Task<B>) => <A>(fa: Task<A>) => Task<B>
/**
* Wrap a value into the type constructor.
*
* @category Applicative
* @since 2.0.0
*/
export declare const of: Applicative1<URI>['of']
/**
* Composes computations in sequence, using the return value of one computation to determine the next computation.
*
* @category Monad
* @since 2.0.0
*/
export declare const chain: <A, B>(f: (a: A) => Task<B>) => (ma: Task<A>) => Task<B>
/**
* Composes computations in sequence, using the return value of one computation to determine the next computation and
* keeping only the result of the first.
*
* Derivable from `Monad`.
*
* @category combinators
* @since 2.0.0
*/
export declare const chainFirst: <A, B>(f: (a: A) => Task<B>) => (ma: Task<A>) => Task<A>
/**
* Derivable from `Monad`.
*
* @category combinators
* @since 2.0.0
*/
export declare const flatten: <A>(mma: Task<Task<A>>) => Task<A>
/**
* @category MonadTask
* @since 2.7.0
*/
export declare const fromTask: MonadTask1<URI>['fromTask']
/**
* @category instances
* @since 2.0.0
*/
export declare const URI = 'Task'
/**
* @category instances
* @since 2.0.0
*/
export declare type URI = typeof URI
declare module './HKT' {
interface URItoKind<A> {
readonly [URI]: Task<A>
}
}
/**
* Lift a semigroup into 'Task', the inner values are concatenated using the provided `Semigroup`.
*
* @example
* import * as T from 'fp-ts/Task'
* import { semigroupString } from 'fp-ts/Semigroup'
*
* async function test() {
* const S = T.getSemigroup(semigroupString)
* const fa = T.of('a')
* const fb = T.of('b')
* assert.deepStrictEqual(await S.concat(fa, fb)(), 'ab')
* }
*
* test()
*
* @category instances
* @since 2.0.0
*/
export declare function getSemigroup<A>(S: Semigroup<A>): Semigroup<Task<A>>
/**
* Lift a monoid into 'Task', the inner values are concatenated using the provided `Monoid`.
*
* @category instances
* @since 2.0.0
*/
export declare function getMonoid<A>(M: Monoid<A>): Monoid<Task<A>>
/**
* Monoid returning the first completed task.
*
* Note: uses `Promise.race` internally.
*
* @example
* import * as T from 'fp-ts/Task'
*
* async function test() {
* const S = T.getRaceMonoid<string>()
* const fa = T.delay(20)(T.of('a'))
* const fb = T.delay(10)(T.of('b'))
* assert.deepStrictEqual(await S.concat(fa, fb)(), 'b')
* }
*
* test()
*
* @category instances
* @since 2.0.0
*/
export declare function getRaceMonoid<A = never>(): Monoid<Task<A>>
/**
* @category instances
* @since 2.7.0
*/
export declare const Functor: Functor1<URI>
/**
* @category instances
* @since 2.7.0
*/
export declare const ApplicativePar: Applicative1<URI>
/**
* @category instances
* @since 2.7.0
*/
export declare const ApplicativeSeq: Applicative1<URI>
/**
* @category instances
* @since 2.0.0
*/
export declare const task: Monad1<URI> & MonadTask1<URI>
/**
* Like `task` but `ap` is sequential
*
* @category instances
* @since 2.0.0
*/
export declare const taskSeq: typeof task
/**
* A `Task` that never completes.
*
* @since 2.0.0
*/
export declare const never: Task<never>
/**
* @since 2.9.0
*/
export declare const Do: Task<{}>
/**
* @since 2.8.0
*/
export declare const bindTo: <N extends string>(name: N) => <A>(fa: Task<A>) => Task<{ [K in N]: A }>
/**
* @since 2.8.0
*/
export declare const bind: <N extends string, A, B>(
name: Exclude<N, keyof A>,
f: (a: A) => Task<B>
) => (fa: Task<A>) => Task<{ [K in N | keyof A]: K extends keyof A ? A[K] : B }>
/**
* @since 2.8.0
*/
export declare const apS: <A, N extends string, B>(
name: Exclude<N, keyof A>,
fb: Task<B>
) => (fa: Task<A>) => Task<{ [K in N | keyof A]: K extends keyof A ? A[K] : B }>
/**
* @since 2.9.0
*/
export declare const traverseArrayWithIndex: <A, B>(
f: (index: number, a: A) => Task<B>
) => (arr: ReadonlyArray<A>) => Task<ReadonlyArray<B>>
/**
* this function map array to task using provided function and transform it to a task of array.
*
* this function has the same behavior of `A.traverse(T.task)` but it's stack safe.
*
* > **This function run all task in parallel for sequential use `traverseSeqArray` **
*
* @example
* import { range } from 'fp-ts/ReadonlyArray'
* import { pipe } from 'fp-ts/function'
* import { of, traverseArray } from 'fp-ts/Task'
* async function test() {
* const arr = range(0, 10)
* assert.deepStrictEqual(await pipe(arr, traverseArray(of))(), arr)
* }
*
* test()
*
* @since 2.9.0
*/
export declare const traverseArray: <A, B>(f: (a: A) => Task<B>) => (arr: ReadonlyArray<A>) => Task<ReadonlyArray<B>>
/**
* this function works like `Promise.all` it will get an array of tasks and return a task of array.
*
* this function has the same behavior of `A.sequence(T.task)` but it's stack safe.
*
* > **This function run all task in parallel for sequential use `sequenceSeqArray` **
*
* @example
* import * as RA from 'fp-ts/ReadonlyArray'
* import { pipe } from 'fp-ts/function'
* import { of, sequenceArray } from 'fp-ts/Task'
*
* async function test() {
* const arr = RA.range(1, 10)
* assert.deepStrictEqual(await pipe(arr, RA.map(of), sequenceArray)(), arr)
* }
*
* test()
*
* @since 2.9.0
*/
export declare const sequenceArray: <A>(arr: ReadonlyArray<Task<A>>) => Task<ReadonlyArray<A>>
/**
* @since 2.9.0
*/
export declare const traverseSeqArrayWithIndex: <A, B>(
f: (index: number, a: A) => Task<B>
) => (arr: ReadonlyArray<A>) => Task<ReadonlyArray<B>>
/**
* runs an action for every element in array then run task sequential, and accumulates the results in the array.
*
* this function has the same behavior of `A.traverse(T.taskSeq)` but it's stack safe.
*
* > **This function run all task sequentially for parallel use `traverseArray` **
*
*
* @since 2.9.0
*/
export declare const traverseSeqArray: <A, B>(f: (a: A) => Task<B>) => (arr: ReadonlyArray<A>) => Task<ReadonlyArray<B>>
/**
* run tasks in array sequential and give a task of array
*
* this function has the same behavior of `A.sequence(T.taskSeq)` but it's stack safe.
*
* > **This function run all task sequentially for parallel use `sequenceArray` **
*
* @since 2.9.0
*/
export declare const sequenceSeqArray: <A>(arr: ReadonlyArray<Task<A>>) => Task<ReadonlyArray<A>>