1096 lines
29 KiB
TypeScript
1096 lines
29 KiB
TypeScript
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/**
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* ```ts
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* type Option<A> = None | Some<A>
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* ```
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*
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* `Option<A>` is a container for an optional value of type `A`. If the value of type `A` is present, the `Option<A>` is
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* an instance of `Some<A>`, containing the present value of type `A`. If the value is absent, the `Option<A>` is an
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* instance of `None`.
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*
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* An option could be looked at as a collection or foldable structure with either one or zero elements.
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* Another way to look at `Option` is: it represents the effect of a possibly failing computation.
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*
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*
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* @example
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* import * as O from 'fp-ts/Option'
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* import { pipe } from 'fp-ts/function'
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*
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* const double = (n: number): number => n * 2
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*
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* export const imperative = (as: ReadonlyArray<number>): string => {
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* const head = (as: ReadonlyArray<number>): number => {
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* if (as.length === 0) {
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* throw new Error()
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* }
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* return as[0]
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* }
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* const inverse = (n: number): number => {
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* if (n === 0) {
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* throw new Error()
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* }
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* return 1 / n
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* }
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* try {
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* return `Result is ${inverse(double(head(as)))}`
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* } catch (e) {
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* return 'no result'
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* }
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* }
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*
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* export const functional = (as: ReadonlyArray<number>): string => {
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* const head = <A>(as: ReadonlyArray<A>): O.Option<A> =>
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* as.length === 0 ? O.none : O.some(as[0])
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* const inverse = (n: number): O.Option<number> =>
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* n === 0 ? O.none : O.some(1 / n)
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* return pipe(
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* as,
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* head,
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* O.map(double),
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* O.chain(inverse),
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* O.match(
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* () => 'no result', // onNone handler
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* (head) => `Result is ${head}` // onSome handler
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* )
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* )
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* }
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*
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* assert.deepStrictEqual(imperative([1, 2, 3]), functional([1, 2, 3]))
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* assert.deepStrictEqual(imperative([]), functional([]))
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* assert.deepStrictEqual(imperative([0]), functional([0]))
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*
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* @since 2.0.0
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*/
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import { Alt1 } from './Alt'
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import { Alternative1 } from './Alternative'
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import { Applicative1 } from './Applicative'
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import { Apply1 } from './Apply'
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import { Chain1 } from './Chain'
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import { Compactable1 } from './Compactable'
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import { Either } from './Either'
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import { Eq } from './Eq'
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import { Extend1 } from './Extend'
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import { Filterable1 } from './Filterable'
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import { Foldable1 } from './Foldable'
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import { FromEither1 } from './FromEither'
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import { Lazy } from './function'
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import { Functor1 } from './Functor'
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import { Monad1 } from './Monad'
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import { MonadThrow1 } from './MonadThrow'
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import { Monoid } from './Monoid'
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import { Ord } from './Ord'
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import { Pointed1 } from './Pointed'
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import { Predicate } from './Predicate'
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import { ReadonlyNonEmptyArray } from './ReadonlyNonEmptyArray'
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import { Refinement } from './Refinement'
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import { Semigroup } from './Semigroup'
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import { Separated } from './Separated'
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import { Show } from './Show'
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import { PipeableTraverse1, Traversable1 } from './Traversable'
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import { PipeableWilt1, PipeableWither1, Witherable1 } from './Witherable'
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import { Zero1 } from './Zero'
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/**
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* @category model
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* @since 2.0.0
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*/
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export interface None {
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readonly _tag: 'None'
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}
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/**
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* @category model
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* @since 2.0.0
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*/
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export interface Some<A> {
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readonly _tag: 'Some'
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readonly value: A
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}
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/**
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* @category model
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* @since 2.0.0
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*/
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export declare type Option<A> = None | Some<A>
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/**
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* `None` doesn't have a constructor, instead you can use it directly as a value. Represents a missing value.
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*
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* @category constructors
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* @since 2.0.0
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*/
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export declare const none: Option<never>
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/**
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* Constructs a `Some`. Represents an optional value that exists.
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*
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* @category constructors
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* @since 2.0.0
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*/
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export declare const some: <A>(a: A) => Option<A>
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/**
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* Returns a *smart constructor* based on the given predicate.
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*
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* @example
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* import { none, some, fromPredicate } from 'fp-ts/Option'
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*
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* const getOption = fromPredicate((n: number) => n >= 0)
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*
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* assert.deepStrictEqual(getOption(-1), none)
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* assert.deepStrictEqual(getOption(1), some(1))
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*
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* @category lifting
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* @since 2.0.0
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*/
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export declare function fromPredicate<A, B extends A>(refinement: Refinement<A, B>): (a: A) => Option<B>
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export declare function fromPredicate<A>(predicate: Predicate<A>): <B extends A>(b: B) => Option<B>
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export declare function fromPredicate<A>(predicate: Predicate<A>): (a: A) => Option<A>
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/**
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* Returns the `Left` value of an `Either` if possible.
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*
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* @example
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* import { getLeft, none, some } from 'fp-ts/Option'
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* import { right, left } from 'fp-ts/Either'
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*
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* assert.deepStrictEqual(getLeft(right(1)), none)
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* assert.deepStrictEqual(getLeft(left('a')), some('a'))
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*
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* @category constructors
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* @since 2.0.0
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*/
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export declare const getLeft: <E, A>(ma: Either<E, A>) => Option<E>
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/**
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* Returns the `Right` value of an `Either` if possible.
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*
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* @example
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* import { getRight, none, some } from 'fp-ts/Option'
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* import { right, left } from 'fp-ts/Either'
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*
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* assert.deepStrictEqual(getRight(right(1)), some(1))
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* assert.deepStrictEqual(getRight(left('a')), none)
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*
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* @category constructors
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* @since 2.0.0
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*/
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export declare const getRight: <E, A>(ma: Either<E, A>) => Option<A>
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/**
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* @category type lambdas
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* @since 2.0.0
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*/
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export declare const URI = 'Option'
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/**
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* @category type lambdas
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* @since 2.0.0
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*/
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export declare type URI = typeof URI
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declare module './HKT' {
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interface URItoKind<A> {
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readonly [URI]: Option<A>
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}
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}
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/**
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* @category instances
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* @since 2.0.0
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*/
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export declare const getShow: <A>(S: Show<A>) => Show<Option<A>>
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/**
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* @example
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* import { none, some, getEq } from 'fp-ts/Option'
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* import * as N from 'fp-ts/number'
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*
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* const E = getEq(N.Eq)
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* assert.strictEqual(E.equals(none, none), true)
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* assert.strictEqual(E.equals(none, some(1)), false)
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* assert.strictEqual(E.equals(some(1), none), false)
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* assert.strictEqual(E.equals(some(1), some(2)), false)
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* assert.strictEqual(E.equals(some(1), some(1)), true)
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*
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* @category instances
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* @since 2.0.0
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*/
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export declare const getEq: <A>(E: Eq<A>) => Eq<Option<A>>
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/**
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* The `Ord` instance allows `Option` values to be compared with
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* `compare`, whenever there is an `Ord` instance for
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* the type the `Option` contains.
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*
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* `None` is considered to be less than any `Some` value.
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*
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*
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* @example
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* import { none, some, getOrd } from 'fp-ts/Option'
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* import * as N from 'fp-ts/number'
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*
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* const O = getOrd(N.Ord)
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* assert.strictEqual(O.compare(none, none), 0)
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* assert.strictEqual(O.compare(none, some(1)), -1)
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* assert.strictEqual(O.compare(some(1), none), 1)
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* assert.strictEqual(O.compare(some(1), some(2)), -1)
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* assert.strictEqual(O.compare(some(1), some(1)), 0)
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*
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* @category instances
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* @since 2.0.0
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*/
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export declare const getOrd: <A>(O: Ord<A>) => Ord<Option<A>>
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/**
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* Monoid returning the left-most non-`None` value. If both operands are `Some`s then the inner values are
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* concatenated using the provided `Semigroup`
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*
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* | x | y | concat(x, y) |
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* | ------- | ------- | ------------------ |
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* | none | none | none |
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* | some(a) | none | some(a) |
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* | none | some(b) | some(b) |
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* | some(a) | some(b) | some(concat(a, b)) |
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*
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* @example
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* import { getMonoid, some, none } from 'fp-ts/Option'
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* import { SemigroupSum } from 'fp-ts/number'
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*
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* const M = getMonoid(SemigroupSum)
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* assert.deepStrictEqual(M.concat(none, none), none)
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* assert.deepStrictEqual(M.concat(some(1), none), some(1))
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* assert.deepStrictEqual(M.concat(none, some(1)), some(1))
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* assert.deepStrictEqual(M.concat(some(1), some(2)), some(3))
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*
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* @category instances
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* @since 2.0.0
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*/
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export declare const getMonoid: <A>(S: Semigroup<A>) => Monoid<Option<A>>
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/**
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* @category mapping
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* @since 2.0.0
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*/
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export declare const map: <A, B>(f: (a: A) => B) => (fa: Option<A>) => Option<B>
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/**
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* @category instances
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* @since 2.7.0
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*/
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export declare const Functor: Functor1<URI>
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/**
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* @category constructors
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* @since 2.7.0
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*/
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export declare const of: <A>(a: A) => Option<A>
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/**
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* @category instances
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* @since 2.10.0
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*/
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export declare const Pointed: Pointed1<URI>
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/**
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* @since 2.0.0
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*/
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export declare const ap: <A>(fa: Option<A>) => <B>(fab: Option<(a: A) => B>) => Option<B>
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/**
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* @category instances
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* @since 2.10.0
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*/
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export declare const Apply: Apply1<URI>
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/**
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* @category instances
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* @since 2.7.0
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*/
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export declare const Applicative: Applicative1<URI>
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/**
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* Composes computations in sequence, using the return value of one computation to determine the next computation.
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*
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* @category sequencing
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* @since 2.0.0
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*/
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export declare const chain: <A, B>(f: (a: A) => Option<B>) => (ma: Option<A>) => Option<B>
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/**
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* @category instances
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* @since 2.10.0
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*/
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export declare const Chain: Chain1<URI>
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/**
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* @category instances
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* @since 2.7.0
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*/
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export declare const Monad: Monad1<URI>
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/**
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* @category folding
|
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* @since 2.0.0
|
||
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*/
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export declare const reduce: <A, B>(b: B, f: (b: B, a: A) => B) => (fa: Option<A>) => B
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/**
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* @category folding
|
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* @since 2.0.0
|
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*/
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export declare const foldMap: <M>(M: Monoid<M>) => <A>(f: (a: A) => M) => (fa: Option<A>) => M
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/**
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* @category folding
|
||
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* @since 2.0.0
|
||
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*/
|
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export declare const reduceRight: <A, B>(b: B, f: (a: A, b: B) => B) => (fa: Option<A>) => B
|
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|
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/**
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||
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* @category instances
|
||
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* @since 2.7.0
|
||
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*/
|
||
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export declare const Foldable: Foldable1<URI>
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/**
|
||
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* Less strict version of [`alt`](#alt).
|
||
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*
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||
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* The `W` suffix (short for **W**idening) means that the return types will be merged.
|
||
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*
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||
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* @category error handling
|
||
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* @since 2.9.0
|
||
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*/
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export declare const altW: <B>(that: Lazy<Option<B>>) => <A>(fa: Option<A>) => Option<A | B>
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/**
|
||
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* Identifies an associative operation on a type constructor. It is similar to `Semigroup`, except that it applies to
|
||
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* types of kind `* -> *`.
|
||
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*
|
||
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* In case of `Option` returns the left-most non-`None` value.
|
||
|
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*
|
||
|
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* | x | y | pipe(x, alt(() => y) |
|
||
|
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* | ------- | ------- | -------------------- |
|
||
|
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* | none | none | none |
|
||
|
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* | some(a) | none | some(a) |
|
||
|
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* | none | some(b) | some(b) |
|
||
|
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* | some(a) | some(b) | some(a) |
|
||
|
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*
|
||
|
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* @example
|
||
|
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* import * as O from 'fp-ts/Option'
|
||
|
|
* import { pipe } from 'fp-ts/function'
|
||
|
|
*
|
||
|
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* assert.deepStrictEqual(
|
||
|
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* pipe(
|
||
|
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* O.none,
|
||
|
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* O.alt(() => O.none)
|
||
|
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* ),
|
||
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* O.none
|
||
|
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* )
|
||
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* assert.deepStrictEqual(
|
||
|
|
* pipe(
|
||
|
|
* O.some('a'),
|
||
|
|
* O.alt<string>(() => O.none)
|
||
|
|
* ),
|
||
|
|
* O.some('a')
|
||
|
|
* )
|
||
|
|
* assert.deepStrictEqual(
|
||
|
|
* pipe(
|
||
|
|
* O.none,
|
||
|
|
* O.alt(() => O.some('b'))
|
||
|
|
* ),
|
||
|
|
* O.some('b')
|
||
|
|
* )
|
||
|
|
* assert.deepStrictEqual(
|
||
|
|
* pipe(
|
||
|
|
* O.some('a'),
|
||
|
|
* O.alt(() => O.some('b'))
|
||
|
|
* ),
|
||
|
|
* O.some('a')
|
||
|
|
* )
|
||
|
|
*
|
||
|
|
* @category error handling
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const alt: <A>(that: Lazy<Option<A>>) => (fa: Option<A>) => Option<A>
|
||
|
|
/**
|
||
|
|
* @category instances
|
||
|
|
* @since 2.7.0
|
||
|
|
*/
|
||
|
|
export declare const Alt: Alt1<URI>
|
||
|
|
/**
|
||
|
|
* @since 2.7.0
|
||
|
|
*/
|
||
|
|
export declare const zero: <A>() => Option<A>
|
||
|
|
/**
|
||
|
|
* @category instances
|
||
|
|
* @since 2.11.0
|
||
|
|
*/
|
||
|
|
export declare const Zero: Zero1<URI>
|
||
|
|
/**
|
||
|
|
* @category do notation
|
||
|
|
* @since 2.11.0
|
||
|
|
*/
|
||
|
|
export declare const guard: (b: boolean) => Option<void>
|
||
|
|
/**
|
||
|
|
* @category instances
|
||
|
|
* @since 2.7.0
|
||
|
|
*/
|
||
|
|
export declare const Alternative: Alternative1<URI>
|
||
|
|
/**
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const extend: <A, B>(f: (wa: Option<A>) => B) => (wa: Option<A>) => Option<B>
|
||
|
|
/**
|
||
|
|
* @category instances
|
||
|
|
* @since 2.7.0
|
||
|
|
*/
|
||
|
|
export declare const Extend: Extend1<URI>
|
||
|
|
/**
|
||
|
|
* @category filtering
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const compact: <A>(fa: Option<Option<A>>) => Option<A>
|
||
|
|
/**
|
||
|
|
* @category filtering
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const separate: <A, B>(ma: Option<Either<A, B>>) => Separated<Option<A>, Option<B>>
|
||
|
|
/**
|
||
|
|
* @category instances
|
||
|
|
* @since 2.7.0
|
||
|
|
*/
|
||
|
|
export declare const Compactable: Compactable1<URI>
|
||
|
|
/**
|
||
|
|
* @category filtering
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const filter: {
|
||
|
|
<A, B extends A>(refinement: Refinement<A, B>): (fa: Option<A>) => Option<B>
|
||
|
|
<A>(predicate: Predicate<A>): <B extends A>(fb: Option<B>) => Option<B>
|
||
|
|
<A>(predicate: Predicate<A>): (fa: Option<A>) => Option<A>
|
||
|
|
}
|
||
|
|
/**
|
||
|
|
* @category filtering
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const filterMap: <A, B>(f: (a: A) => Option<B>) => (fa: Option<A>) => Option<B>
|
||
|
|
/**
|
||
|
|
* @category filtering
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const partition: {
|
||
|
|
<A, B extends A>(refinement: Refinement<A, B>): (fa: Option<A>) => Separated<Option<A>, Option<B>>
|
||
|
|
<A>(predicate: Predicate<A>): <B extends A>(fb: Option<B>) => Separated<Option<B>, Option<B>>
|
||
|
|
<A>(predicate: Predicate<A>): (fa: Option<A>) => Separated<Option<A>, Option<A>>
|
||
|
|
}
|
||
|
|
/**
|
||
|
|
* @category filtering
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const partitionMap: <A, B, C>(
|
||
|
|
f: (a: A) => Either<B, C>
|
||
|
|
) => (fa: Option<A>) => Separated<Option<B>, Option<C>>
|
||
|
|
/**
|
||
|
|
* @category instances
|
||
|
|
* @since 2.7.0
|
||
|
|
*/
|
||
|
|
export declare const Filterable: Filterable1<URI>
|
||
|
|
/**
|
||
|
|
* @category traversing
|
||
|
|
* @since 2.6.3
|
||
|
|
*/
|
||
|
|
export declare const traverse: PipeableTraverse1<URI>
|
||
|
|
/**
|
||
|
|
* @category traversing
|
||
|
|
* @since 2.6.3
|
||
|
|
*/
|
||
|
|
export declare const sequence: Traversable1<URI>['sequence']
|
||
|
|
/**
|
||
|
|
* @category instances
|
||
|
|
* @since 2.7.0
|
||
|
|
*/
|
||
|
|
export declare const Traversable: Traversable1<URI>
|
||
|
|
/**
|
||
|
|
* @category filtering
|
||
|
|
* @since 2.6.5
|
||
|
|
*/
|
||
|
|
export declare const wither: PipeableWither1<URI>
|
||
|
|
/**
|
||
|
|
* @category filtering
|
||
|
|
* @since 2.6.5
|
||
|
|
*/
|
||
|
|
export declare const wilt: PipeableWilt1<URI>
|
||
|
|
/**
|
||
|
|
* @category instances
|
||
|
|
* @since 2.7.0
|
||
|
|
*/
|
||
|
|
export declare const Witherable: Witherable1<URI>
|
||
|
|
/**
|
||
|
|
* @since 2.7.0
|
||
|
|
*/
|
||
|
|
export declare const throwError: MonadThrow1<URI>['throwError']
|
||
|
|
/**
|
||
|
|
* @category instances
|
||
|
|
* @since 2.7.0
|
||
|
|
*/
|
||
|
|
export declare const MonadThrow: MonadThrow1<URI>
|
||
|
|
/**
|
||
|
|
* Transforms an `Either` to an `Option` discarding the error.
|
||
|
|
*
|
||
|
|
* Alias of [getRight](#getright)
|
||
|
|
*
|
||
|
|
* @category conversions
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const fromEither: <A>(fa: Either<unknown, A>) => Option<A>
|
||
|
|
/**
|
||
|
|
* @category instances
|
||
|
|
* @since 2.11.0
|
||
|
|
*/
|
||
|
|
export declare const FromEither: FromEither1<URI>
|
||
|
|
/**
|
||
|
|
* Returns `true` if the option is an instance of `Some`, `false` otherwise.
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* import { some, none, isSome } from 'fp-ts/Option'
|
||
|
|
*
|
||
|
|
* assert.strictEqual(isSome(some(1)), true)
|
||
|
|
* assert.strictEqual(isSome(none), false)
|
||
|
|
*
|
||
|
|
* @category refinements
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const isSome: <A>(fa: Option<A>) => fa is Some<A>
|
||
|
|
/**
|
||
|
|
* Returns `true` if the option is `None`, `false` otherwise.
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* import { some, none, isNone } from 'fp-ts/Option'
|
||
|
|
*
|
||
|
|
* assert.strictEqual(isNone(some(1)), false)
|
||
|
|
* assert.strictEqual(isNone(none), true)
|
||
|
|
*
|
||
|
|
* @category refinements
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const isNone: (fa: Option<unknown>) => fa is None
|
||
|
|
/**
|
||
|
|
* Less strict version of [`match`](#match).
|
||
|
|
*
|
||
|
|
* The `W` suffix (short for **W**idening) means that the handler return types will be merged.
|
||
|
|
*
|
||
|
|
* @category pattern matching
|
||
|
|
* @since 2.10.0
|
||
|
|
*/
|
||
|
|
export declare const matchW: <B, A, C>(onNone: Lazy<B>, onSome: (a: A) => C) => (ma: Option<A>) => B | C
|
||
|
|
/**
|
||
|
|
* Alias of [`matchW`](#matchw).
|
||
|
|
*
|
||
|
|
* @category pattern matching
|
||
|
|
* @since 2.10.0
|
||
|
|
*/
|
||
|
|
export declare const foldW: <B, A, C>(onNone: Lazy<B>, onSome: (a: A) => C) => (ma: Option<A>) => B | C
|
||
|
|
/**
|
||
|
|
* Takes a (lazy) default value, a function, and an `Option` value, if the `Option` value is `None` the default value is
|
||
|
|
* returned, otherwise the function is applied to the value inside the `Some` and the result is returned.
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* import { some, none, match } from 'fp-ts/Option'
|
||
|
|
* import { pipe } from 'fp-ts/function'
|
||
|
|
*
|
||
|
|
* assert.strictEqual(
|
||
|
|
* pipe(
|
||
|
|
* some(1),
|
||
|
|
* match(() => 'a none', a => `a some containing ${a}`)
|
||
|
|
* ),
|
||
|
|
* 'a some containing 1'
|
||
|
|
* )
|
||
|
|
*
|
||
|
|
* assert.strictEqual(
|
||
|
|
* pipe(
|
||
|
|
* none,
|
||
|
|
* match(() => 'a none', a => `a some containing ${a}`)
|
||
|
|
* ),
|
||
|
|
* 'a none'
|
||
|
|
* )
|
||
|
|
*
|
||
|
|
* @category pattern matching
|
||
|
|
* @since 2.10.0
|
||
|
|
*/
|
||
|
|
export declare const match: <A, B>(onNone: Lazy<B>, onSome: (a: A) => B) => (ma: Option<A>) => B
|
||
|
|
/**
|
||
|
|
* Alias of [`match`](#match).
|
||
|
|
*
|
||
|
|
* @category pattern matching
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const fold: <A, B>(onNone: Lazy<B>, onSome: (a: A) => B) => (ma: Option<A>) => B
|
||
|
|
/**
|
||
|
|
* Less strict version of [`getOrElse`](#getorelse).
|
||
|
|
*
|
||
|
|
* The `W` suffix (short for **W**idening) means that the handler return type will be merged.
|
||
|
|
*
|
||
|
|
* @category error handling
|
||
|
|
* @since 2.6.0
|
||
|
|
*/
|
||
|
|
export declare const getOrElseW: <B>(onNone: Lazy<B>) => <A>(ma: Option<A>) => B | A
|
||
|
|
/**
|
||
|
|
* Extracts the value out of the structure, if it exists. Otherwise returns the given default value
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* import { some, none, getOrElse } from 'fp-ts/Option'
|
||
|
|
* import { pipe } from 'fp-ts/function'
|
||
|
|
*
|
||
|
|
* assert.strictEqual(
|
||
|
|
* pipe(
|
||
|
|
* some(1),
|
||
|
|
* getOrElse(() => 0)
|
||
|
|
* ),
|
||
|
|
* 1
|
||
|
|
* )
|
||
|
|
* assert.strictEqual(
|
||
|
|
* pipe(
|
||
|
|
* none,
|
||
|
|
* getOrElse(() => 0)
|
||
|
|
* ),
|
||
|
|
* 0
|
||
|
|
* )
|
||
|
|
*
|
||
|
|
* @category error handling
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const getOrElse: <A>(onNone: Lazy<A>) => (ma: Option<A>) => A
|
||
|
|
/**
|
||
|
|
* @category mapping
|
||
|
|
* @since 2.10.0
|
||
|
|
*/
|
||
|
|
export declare const flap: <A>(a: A) => <B>(fab: Option<(a: A) => B>) => Option<B>
|
||
|
|
/**
|
||
|
|
* Combine two effectful actions, keeping only the result of the first.
|
||
|
|
*
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const apFirst: <B>(second: Option<B>) => <A>(first: Option<A>) => Option<A>
|
||
|
|
/**
|
||
|
|
* Combine two effectful actions, keeping only the result of the second.
|
||
|
|
*
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const apSecond: <B>(second: Option<B>) => <A>(first: Option<A>) => Option<B>
|
||
|
|
/**
|
||
|
|
* @category sequencing
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const flatten: <A>(mma: Option<Option<A>>) => Option<A>
|
||
|
|
/**
|
||
|
|
* Composes computations in sequence, using the return value of one computation to determine the next computation and
|
||
|
|
* keeping only the result of the first.
|
||
|
|
*
|
||
|
|
* @category sequencing
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const chainFirst: <A, B>(f: (a: A) => Option<B>) => (first: Option<A>) => Option<A>
|
||
|
|
/**
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const duplicate: <A>(ma: Option<A>) => Option<Option<A>>
|
||
|
|
/**
|
||
|
|
* @category lifting
|
||
|
|
* @since 2.11.0
|
||
|
|
*/
|
||
|
|
export declare const fromEitherK: <E, A extends ReadonlyArray<unknown>, B>(
|
||
|
|
f: (...a: A) => Either<E, B>
|
||
|
|
) => (...a: A) => Option<B>
|
||
|
|
/**
|
||
|
|
* @category sequencing
|
||
|
|
* @since 2.11.0
|
||
|
|
*/
|
||
|
|
export declare const chainEitherK: <E, A, B>(f: (a: A) => Either<E, B>) => (ma: Option<A>) => Option<B>
|
||
|
|
/**
|
||
|
|
* @category sequencing
|
||
|
|
* @since 2.12.0
|
||
|
|
*/
|
||
|
|
export declare const chainFirstEitherK: <E, A, B>(f: (a: A) => Either<E, B>) => (ma: Option<A>) => Option<A>
|
||
|
|
/**
|
||
|
|
* Constructs a new `Option` from a nullable type. If the value is `null` or `undefined`, returns `None`, otherwise
|
||
|
|
* returns the value wrapped in a `Some`.
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* import { none, some, fromNullable } from 'fp-ts/Option'
|
||
|
|
*
|
||
|
|
* assert.deepStrictEqual(fromNullable(undefined), none)
|
||
|
|
* assert.deepStrictEqual(fromNullable(null), none)
|
||
|
|
* assert.deepStrictEqual(fromNullable(1), some(1))
|
||
|
|
*
|
||
|
|
* @category conversions
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const fromNullable: <A>(a: A) => Option<NonNullable<A>>
|
||
|
|
/**
|
||
|
|
* Transforms an exception into an `Option`. If `f` throws, returns `None`, otherwise returns the output wrapped in a
|
||
|
|
* `Some`.
|
||
|
|
*
|
||
|
|
* See also [`tryCatchK`](#trycatchk).
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* import { none, some, tryCatch } from 'fp-ts/Option'
|
||
|
|
*
|
||
|
|
* assert.deepStrictEqual(
|
||
|
|
* tryCatch(() => {
|
||
|
|
* throw new Error()
|
||
|
|
* }),
|
||
|
|
* none
|
||
|
|
* )
|
||
|
|
* assert.deepStrictEqual(tryCatch(() => 1), some(1))
|
||
|
|
*
|
||
|
|
* @category interop
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const tryCatch: <A>(f: Lazy<A>) => Option<A>
|
||
|
|
/**
|
||
|
|
* Converts a function that may throw to one returning a `Option`.
|
||
|
|
*
|
||
|
|
* @category interop
|
||
|
|
* @since 2.10.0
|
||
|
|
*/
|
||
|
|
export declare const tryCatchK: <A extends readonly unknown[], B>(f: (...a: A) => B) => (...a: A) => Option<B>
|
||
|
|
/**
|
||
|
|
* Returns a *smart constructor* from a function that returns a nullable value.
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* import { fromNullableK, none, some } from 'fp-ts/Option'
|
||
|
|
*
|
||
|
|
* const f = (s: string): number | undefined => {
|
||
|
|
* const n = parseFloat(s)
|
||
|
|
* return isNaN(n) ? undefined : n
|
||
|
|
* }
|
||
|
|
*
|
||
|
|
* const g = fromNullableK(f)
|
||
|
|
*
|
||
|
|
* assert.deepStrictEqual(g('1'), some(1))
|
||
|
|
* assert.deepStrictEqual(g('a'), none)
|
||
|
|
*
|
||
|
|
* @category lifting
|
||
|
|
* @since 2.9.0
|
||
|
|
*/
|
||
|
|
export declare const fromNullableK: <A extends ReadonlyArray<unknown>, B>(
|
||
|
|
f: (...a: A) => B | null | undefined
|
||
|
|
) => (...a: A) => Option<NonNullable<B>>
|
||
|
|
/**
|
||
|
|
* This is `chain` + `fromNullable`, useful when working with optional values.
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* import { some, none, fromNullable, chainNullableK } from 'fp-ts/Option'
|
||
|
|
* import { pipe } from 'fp-ts/function'
|
||
|
|
*
|
||
|
|
* interface Employee {
|
||
|
|
* readonly company?: {
|
||
|
|
* readonly address?: {
|
||
|
|
* readonly street?: {
|
||
|
|
* readonly name?: string
|
||
|
|
* }
|
||
|
|
* }
|
||
|
|
* }
|
||
|
|
* }
|
||
|
|
*
|
||
|
|
* const employee1: Employee = { company: { address: { street: { name: 'high street' } } } }
|
||
|
|
*
|
||
|
|
* assert.deepStrictEqual(
|
||
|
|
* pipe(
|
||
|
|
* fromNullable(employee1.company),
|
||
|
|
* chainNullableK(company => company.address),
|
||
|
|
* chainNullableK(address => address.street),
|
||
|
|
* chainNullableK(street => street.name)
|
||
|
|
* ),
|
||
|
|
* some('high street')
|
||
|
|
* )
|
||
|
|
*
|
||
|
|
* const employee2: Employee = { company: { address: { street: {} } } }
|
||
|
|
*
|
||
|
|
* assert.deepStrictEqual(
|
||
|
|
* pipe(
|
||
|
|
* fromNullable(employee2.company),
|
||
|
|
* chainNullableK(company => company.address),
|
||
|
|
* chainNullableK(address => address.street),
|
||
|
|
* chainNullableK(street => street.name)
|
||
|
|
* ),
|
||
|
|
* none
|
||
|
|
* )
|
||
|
|
*
|
||
|
|
* @category sequencing
|
||
|
|
* @since 2.9.0
|
||
|
|
*/
|
||
|
|
export declare const chainNullableK: <A, B>(
|
||
|
|
f: (a: A) => B | null | undefined
|
||
|
|
) => (ma: Option<A>) => Option<NonNullable<B>>
|
||
|
|
/**
|
||
|
|
* Extracts the value out of the structure, if it exists. Otherwise returns `null`.
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* import { some, none, toNullable } from 'fp-ts/Option'
|
||
|
|
* import { pipe } from 'fp-ts/function'
|
||
|
|
*
|
||
|
|
* assert.strictEqual(
|
||
|
|
* pipe(
|
||
|
|
* some(1),
|
||
|
|
* toNullable
|
||
|
|
* ),
|
||
|
|
* 1
|
||
|
|
* )
|
||
|
|
* assert.strictEqual(
|
||
|
|
* pipe(
|
||
|
|
* none,
|
||
|
|
* toNullable
|
||
|
|
* ),
|
||
|
|
* null
|
||
|
|
* )
|
||
|
|
*
|
||
|
|
* @category conversions
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const toNullable: <A>(ma: Option<A>) => A | null
|
||
|
|
/**
|
||
|
|
* Extracts the value out of the structure, if it exists. Otherwise returns `undefined`.
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* import { some, none, toUndefined } from 'fp-ts/Option'
|
||
|
|
* import { pipe } from 'fp-ts/function'
|
||
|
|
*
|
||
|
|
* assert.strictEqual(
|
||
|
|
* pipe(
|
||
|
|
* some(1),
|
||
|
|
* toUndefined
|
||
|
|
* ),
|
||
|
|
* 1
|
||
|
|
* )
|
||
|
|
* assert.strictEqual(
|
||
|
|
* pipe(
|
||
|
|
* none,
|
||
|
|
* toUndefined
|
||
|
|
* ),
|
||
|
|
* undefined
|
||
|
|
* )
|
||
|
|
*
|
||
|
|
* @category conversions
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const toUndefined: <A>(ma: Option<A>) => A | undefined
|
||
|
|
/**
|
||
|
|
* Returns `true` if `ma` contains `a`
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* import { some, none, elem } from 'fp-ts/Option'
|
||
|
|
* import { pipe } from 'fp-ts/function'
|
||
|
|
* import * as N from 'fp-ts/number'
|
||
|
|
*
|
||
|
|
* assert.strictEqual(pipe(some(1), elem(N.Eq)(1)), true)
|
||
|
|
* assert.strictEqual(pipe(some(1), elem(N.Eq)(2)), false)
|
||
|
|
* assert.strictEqual(pipe(none, elem(N.Eq)(1)), false)
|
||
|
|
*
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare function elem<A>(E: Eq<A>): {
|
||
|
|
(a: A): (ma: Option<A>) => boolean
|
||
|
|
(a: A, ma: Option<A>): boolean
|
||
|
|
}
|
||
|
|
/**
|
||
|
|
* Returns `true` if the predicate is satisfied by the wrapped value
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* import { some, none, exists } from 'fp-ts/Option'
|
||
|
|
* import { pipe } from 'fp-ts/function'
|
||
|
|
*
|
||
|
|
* assert.strictEqual(
|
||
|
|
* pipe(
|
||
|
|
* some(1),
|
||
|
|
* exists(n => n > 0)
|
||
|
|
* ),
|
||
|
|
* true
|
||
|
|
* )
|
||
|
|
* assert.strictEqual(
|
||
|
|
* pipe(
|
||
|
|
* some(1),
|
||
|
|
* exists(n => n > 1)
|
||
|
|
* ),
|
||
|
|
* false
|
||
|
|
* )
|
||
|
|
* assert.strictEqual(
|
||
|
|
* pipe(
|
||
|
|
* none,
|
||
|
|
* exists(n => n > 0)
|
||
|
|
* ),
|
||
|
|
* false
|
||
|
|
* )
|
||
|
|
*
|
||
|
|
* @since 2.0.0
|
||
|
|
*/
|
||
|
|
export declare const exists: <A>(predicate: Predicate<A>) => (ma: Option<A>) => boolean
|
||
|
|
/**
|
||
|
|
* @category do notation
|
||
|
|
* @since 2.9.0
|
||
|
|
*/
|
||
|
|
export declare const Do: Option<{}>
|
||
|
|
/**
|
||
|
|
* @category do notation
|
||
|
|
* @since 2.8.0
|
||
|
|
*/
|
||
|
|
export declare const bindTo: <N extends string>(name: N) => <A>(fa: Option<A>) => Option<{ readonly [K in N]: A }>
|
||
|
|
declare const let_: <N extends string, A, B>(
|
||
|
|
name: Exclude<N, keyof A>,
|
||
|
|
f: (a: A) => B
|
||
|
|
) => (fa: Option<A>) => Option<{ readonly [K in N | keyof A]: K extends keyof A ? A[K] : B }>
|
||
|
|
export {
|
||
|
|
/**
|
||
|
|
* @category do notation
|
||
|
|
* @since 2.13.0
|
||
|
|
*/
|
||
|
|
let_ as let
|
||
|
|
}
|
||
|
|
/**
|
||
|
|
* @category do notation
|
||
|
|
* @since 2.8.0
|
||
|
|
*/
|
||
|
|
export declare const bind: <N extends string, A, B>(
|
||
|
|
name: Exclude<N, keyof A>,
|
||
|
|
f: (a: A) => Option<B>
|
||
|
|
) => (ma: Option<A>) => Option<{ readonly [K in N | keyof A]: K extends keyof A ? A[K] : B }>
|
||
|
|
/**
|
||
|
|
* @category do notation
|
||
|
|
* @since 2.8.0
|
||
|
|
*/
|
||
|
|
export declare const apS: <N extends string, A, B>(
|
||
|
|
name: Exclude<N, keyof A>,
|
||
|
|
fb: Option<B>
|
||
|
|
) => (fa: Option<A>) => Option<{ readonly [K in N | keyof A]: K extends keyof A ? A[K] : B }>
|
||
|
|
/**
|
||
|
|
* @since 2.11.0
|
||
|
|
*/
|
||
|
|
export declare const ApT: Option<readonly []>
|
||
|
|
/**
|
||
|
|
* Equivalent to `ReadonlyNonEmptyArray#traverseWithIndex(Applicative)`.
|
||
|
|
*
|
||
|
|
* @category traversing
|
||
|
|
* @since 2.11.0
|
||
|
|
*/
|
||
|
|
export declare const traverseReadonlyNonEmptyArrayWithIndex: <A, B>(
|
||
|
|
f: (index: number, a: A) => Option<B>
|
||
|
|
) => (as: ReadonlyNonEmptyArray<A>) => Option<ReadonlyNonEmptyArray<B>>
|
||
|
|
/**
|
||
|
|
* Equivalent to `ReadonlyArray#traverseWithIndex(Applicative)`.
|
||
|
|
*
|
||
|
|
* @category traversing
|
||
|
|
* @since 2.11.0
|
||
|
|
*/
|
||
|
|
export declare const traverseReadonlyArrayWithIndex: <A, B>(
|
||
|
|
f: (index: number, a: A) => Option<B>
|
||
|
|
) => (as: readonly A[]) => Option<readonly B[]>
|
||
|
|
/**
|
||
|
|
* Equivalent to `ReadonlyArray#traverseWithIndex(Applicative)`.
|
||
|
|
*
|
||
|
|
* @category traversing
|
||
|
|
* @since 2.9.0
|
||
|
|
*/
|
||
|
|
export declare const traverseArrayWithIndex: <A, B>(
|
||
|
|
f: (index: number, a: A) => Option<B>
|
||
|
|
) => (as: ReadonlyArray<A>) => Option<ReadonlyArray<B>>
|
||
|
|
/**
|
||
|
|
* Equivalent to `ReadonlyArray#traverse(Applicative)`.
|
||
|
|
*
|
||
|
|
* @category traversing
|
||
|
|
* @since 2.9.0
|
||
|
|
*/
|
||
|
|
export declare const traverseArray: <A, B>(f: (a: A) => Option<B>) => (as: readonly A[]) => Option<readonly B[]>
|
||
|
|
/**
|
||
|
|
* Equivalent to `ReadonlyArray#sequence(Applicative)`.
|
||
|
|
*
|
||
|
|
* @category traversing
|
||
|
|
* @since 2.9.0
|
||
|
|
*/
|
||
|
|
export declare const sequenceArray: <A>(arr: ReadonlyArray<Option<A>>) => Option<ReadonlyArray<A>>
|
||
|
|
/**
|
||
|
|
* Use `Refinement` module instead.
|
||
|
|
*
|
||
|
|
* @category zone of death
|
||
|
|
* @since 2.0.0
|
||
|
|
* @deprecated
|
||
|
|
*/
|
||
|
|
export declare function getRefinement<A, B extends A>(getOption: (a: A) => Option<B>): Refinement<A, B>
|
||
|
|
/**
|
||
|
|
* Use [`chainNullableK`](#chainnullablek) instead.
|
||
|
|
*
|
||
|
|
* @category zone of death
|
||
|
|
* @since 2.0.0
|
||
|
|
* @deprecated
|
||
|
|
*/
|
||
|
|
export declare const mapNullable: <A, B>(f: (a: A) => B | null | undefined) => (ma: Option<A>) => Option<NonNullable<B>>
|
||
|
|
/**
|
||
|
|
* This instance is deprecated, use small, specific instances instead.
|
||
|
|
* For example if a function needs a `Functor` instance, pass `O.Functor` instead of `O.option`
|
||
|
|
* (where `O` is from `import O from 'fp-ts/Option'`)
|
||
|
|
*
|
||
|
|
* @category zone of death
|
||
|
|
* @since 2.0.0
|
||
|
|
* @deprecated
|
||
|
|
*/
|
||
|
|
export declare const option: Monad1<URI> &
|
||
|
|
Foldable1<URI> &
|
||
|
|
Alternative1<URI> &
|
||
|
|
Extend1<URI> &
|
||
|
|
Witherable1<URI> &
|
||
|
|
MonadThrow1<URI>
|
||
|
|
/**
|
||
|
|
* Use [`getApplySemigroup`](./Apply.ts.html#getapplysemigroup) instead.
|
||
|
|
*
|
||
|
|
* @category zone of death
|
||
|
|
* @since 2.0.0
|
||
|
|
* @deprecated
|
||
|
|
*/
|
||
|
|
export declare const getApplySemigroup: <A>(S: Semigroup<A>) => Semigroup<Option<A>>
|
||
|
|
/**
|
||
|
|
* Use [`getApplicativeMonoid`](./Applicative.ts.html#getapplicativemonoid) instead.
|
||
|
|
*
|
||
|
|
* @category zone of death
|
||
|
|
* @since 2.0.0
|
||
|
|
* @deprecated
|
||
|
|
*/
|
||
|
|
export declare const getApplyMonoid: <A>(M: Monoid<A>) => Monoid<Option<A>>
|
||
|
|
/**
|
||
|
|
* Use
|
||
|
|
*
|
||
|
|
* ```ts
|
||
|
|
* import { first } from 'fp-ts/Semigroup'
|
||
|
|
* import { getMonoid } from 'fp-ts/Option'
|
||
|
|
*
|
||
|
|
* getMonoid(first())
|
||
|
|
* ```
|
||
|
|
*
|
||
|
|
* instead.
|
||
|
|
*
|
||
|
|
* Monoid returning the left-most non-`None` value
|
||
|
|
*
|
||
|
|
* | x | y | concat(x, y) |
|
||
|
|
* | ------- | ------- | ------------ |
|
||
|
|
* | none | none | none |
|
||
|
|
* | some(a) | none | some(a) |
|
||
|
|
* | none | some(b) | some(b) |
|
||
|
|
* | some(a) | some(b) | some(a) |
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* import { getFirstMonoid, some, none } from 'fp-ts/Option'
|
||
|
|
*
|
||
|
|
* const M = getFirstMonoid<number>()
|
||
|
|
* assert.deepStrictEqual(M.concat(none, none), none)
|
||
|
|
* assert.deepStrictEqual(M.concat(some(1), none), some(1))
|
||
|
|
* assert.deepStrictEqual(M.concat(none, some(2)), some(2))
|
||
|
|
* assert.deepStrictEqual(M.concat(some(1), some(2)), some(1))
|
||
|
|
*
|
||
|
|
* @category zone of death
|
||
|
|
* @since 2.0.0
|
||
|
|
* @deprecated
|
||
|
|
*/
|
||
|
|
export declare const getFirstMonoid: <A = never>() => Monoid<Option<A>>
|
||
|
|
/**
|
||
|
|
* Use
|
||
|
|
*
|
||
|
|
* ```ts
|
||
|
|
* import { last } from 'fp-ts/Semigroup'
|
||
|
|
* import { getMonoid } from 'fp-ts/Option'
|
||
|
|
*
|
||
|
|
* getMonoid(last())
|
||
|
|
* ```
|
||
|
|
*
|
||
|
|
* instead.
|
||
|
|
*
|
||
|
|
* Monoid returning the right-most non-`None` value
|
||
|
|
*
|
||
|
|
* | x | y | concat(x, y) |
|
||
|
|
* | ------- | ------- | ------------ |
|
||
|
|
* | none | none | none |
|
||
|
|
* | some(a) | none | some(a) |
|
||
|
|
* | none | some(b) | some(b) |
|
||
|
|
* | some(a) | some(b) | some(b) |
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* import { getLastMonoid, some, none } from 'fp-ts/Option'
|
||
|
|
*
|
||
|
|
* const M = getLastMonoid<number>()
|
||
|
|
* assert.deepStrictEqual(M.concat(none, none), none)
|
||
|
|
* assert.deepStrictEqual(M.concat(some(1), none), some(1))
|
||
|
|
* assert.deepStrictEqual(M.concat(none, some(2)), some(2))
|
||
|
|
* assert.deepStrictEqual(M.concat(some(1), some(2)), some(2))
|
||
|
|
*
|
||
|
|
* @category zone of death
|
||
|
|
* @since 2.0.0
|
||
|
|
* @deprecated
|
||
|
|
*/
|
||
|
|
export declare const getLastMonoid: <A = never>() => Monoid<Option<A>>
|