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IoEither

Instances​

Combinators​

Constructors​

Conversions​

Do notation​

Error handling​

Filtering​

Instance Methods​

Interop​

Legacy​

Lifting​

Mapping​

Model​

Pattern matching​

Sequencing​

Traversing​

Type lambdas​

Utilities​

Instances​

Alt​

Signature​

export declare const Alt: Alt2<URI>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

ApplicativePar​

Runs computations in parallel.

Signature​

export declare const ApplicativePar: Applicative2<URI>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

ApplicativeSeq​

Runs computations sequentially.

Signature​

export declare const ApplicativeSeq: Applicative2<URI>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

ApplyPar​

Runs computations in parallel.

Signature​

export declare const ApplyPar: Apply2<URI>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Bifunctor​

Signature​

export declare const Bifunctor: Bifunctor2<URI>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Chain​

Signature​

export declare const Chain: chainable.Chain2<URI>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

ChainRec​

Signature​

export declare const ChainRec: ChainRec2<URI>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2022-present Jacob Alford

FromEither​

Signature​

export declare const FromEither: FromEither2<URI>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

FromIO​

Signature​

export declare const FromIO: FromIO2<URI>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Functor​

Signature​

export declare const Functor: Functor2<URI>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Monad​

Signature​

export declare const Monad: Monad2<URI>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

MonadIO​

Signature​

export declare const MonadIO: MonadIO2<URI>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

MonadThrow​

Signature​

export declare const MonadThrow: MonadThrow2<URI>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Pointed​

Signature​

export declare const Pointed: Pointed2<URI>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Combinators​

tap​

Composes computations in sequence, using the return value of one computation to determine the next computation and keeping only the result of the first.

Signature​

export declare const tap: {
  <E1, A, E2, _>(self: IOEither<E1, A>, f: (a: A) => IOEither<E2, _>): IOEither<E1 | E2, A>
  <A, E2, _>(f: (a: A) => IOEither<E2, _>): <E1>(self: IOEither<E1, A>) => IOEither<E2 | E1, A>
}

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

tapEither​

Composes computations in sequence, using the return value of one computation to determine the next computation and keeping only the result of the first.

Signature​

export declare const tapEither: {
  <A, E2, _>(f: (a: A) => Either<E2, _>): <E1>(self: IOEither<E1, A>) => IOEither<E2 | E1, A>
  <E1, A, E2, _>(self: IOEither<E1, A>, f: (a: A) => Either<E2, _>): IOEither<E1 | E2, A>
}

Details​

  • Added in 0.1.0

Example​

import { pipe } from '@fp-tx/core/function'
import * as IOE from '@fp-tx/core/IOEither'
import * as E from '@fp-tx/core/Either'

const compute = (value: string) =>
  pipe(
    IOE.of(value),
    IOE.tapEither(() => (value.length > 0 ? E.right('ok') : E.left('error'))),
  )

assert.deepStrictEqual(compute('')(), E.left('error'))
assert.deepStrictEqual(compute('fp-ts')(), E.right('fp-ts'))

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

tapIO​

Composes computations in sequence, using the return value of one computation to determine the next computation and keeping only the result of the first.

Signature​

export declare const tapIO: {
  <A, _>(f: (a: A) => IO<_>): <E>(self: IOEither<E, A>) => IOEither<E, A>
  <E, A, _>(self: IOEither<E, A>, f: (a: A) => IO<_>): IOEither<E, A>
}

Details​

  • Added in 0.1.0

Example​

import { pipe } from '@fp-tx/core/function'
import * as IOE from '@fp-tx/core/IOEither'
import * as E from '@fp-tx/core/Either'
import * as Console from '@fp-tx/core/Console'

const sayHello = (value: string) => Console.log(`Hello, ${value}`)

// Will produce `Hello, fp-ts` to the stdout
const effectA = IOE.tapIO(IOE.of('fp-ts'), sayHello)

// No output to the stdout
const effectB = pipe(IOE.left<string>('error'), IOE.tapIO(sayHello))

assert.deepStrictEqual(effectA(), E.right('fp-ts'))
assert.deepStrictEqual(effectB(), E.left('error'))

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Constructors​

left​

Signature​

export declare const left: <E = never, A = never>(l: E) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

leftIO​

Signature​

export declare const leftIO: <E = never, A = never>(me: IO<E>) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

of​

Signature​

export declare const of: <E = never, A = never>(a: A) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Signature​

export declare const right: <E = never, A = never>(a: A) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

rightIO​

Signature​

export declare const rightIO: <E = never, A = never>(ma: IO<A>) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Conversions​

fromEither​

Signature​

export declare const fromEither: <E, A>(fa: Either<E, A>) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

fromIO​

Signature​

export declare const fromIO: <A, E = never>(fa: IO<A>) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

fromOption​

Signature​

export declare const fromOption: <E>(onNone: LazyArg<E>) => <A>(fa: Option<A>) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

toUnion​

Signature​

export declare const toUnion: <E, A>(fa: IOEither<E, A>) => IO<E | A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Do notation​

Do​

Signature​

export declare const Do: IOEither<never, {}>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

apS​

Signature​

export declare const apS: <N extends string, A, E, B>(
  name: Exclude<N, keyof A>,
  fb: IOEither<E, B>,
) => (fa: IOEither<E, A>) => IOEither<E, { readonly [K in N | keyof A]: K extends keyof A ? A[K] : B }>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

apSW​

Less strict version of apS.

The W suffix (short for Widening) means that the error types will be merged.

Signature​

export declare const apSW: <A, N extends string, E2, B>(
  name: Exclude<N, keyof A>,
  fb: IOEither<E2, B>,
) => <E1>(fa: IOEither<E1, A>) => IOEither<
  E1 | E2,
  {
    readonly [K in keyof A | N]: K extends keyof A ? A[K] : B
  }
>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

bind​

Signature​

export declare const bind: <N extends string, A, E, B>(
  name: Exclude<N, keyof A>,
  f: (a: A) => IOEither<E, B>,
) => (ma: IOEither<E, A>) => IOEither<E, { readonly [K in N | keyof A]: K extends keyof A ? A[K] : B }>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

bindTo​

Signature​

export declare const bindTo: <N extends string>(
  name: N,
) => <E, A>(fa: IOEither<E, A>) => IOEither<E, { readonly [K in N]: A }>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

bindW​

The W suffix (short for Widening) means that the error types will be merged.

Signature​

export declare const bindW: <N extends string, A, E2, B>(
  name: Exclude<N, keyof A>,
  f: (a: A) => IOEither<E2, B>,
) => <E1>(fa: IOEither<E1, A>) => IOEither<
  E1 | E2,
  {
    readonly [K in keyof A | N]: K extends keyof A ? A[K] : B
  }
>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Error handling​

alt​

Identifies an associative operation on a type constructor. It is similar to Semigroup, except that it applies to types of kind * -> *.

Signature​

export declare const alt: <E, A>(that: LazyArg<IOEither<E, A>>) => (fa: IOEither<E, A>) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

altW​

Less strict version of alt.

The W suffix (short for Widening) means that the error and the return types will be merged.

Signature​

export declare const altW: <E2, B>(
  that: LazyArg<IOEither<E2, B>>,
) => <E1, A>(fa: IOEither<E1, A>) => IOEither<E2, A | B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

getAltIOValidation​

The default Alt instance returns the last error, if you want to get all errors you need to provide a way to concatenate them via a Semigroup.

See getAltValidation.

Signature​

export declare function getAltIOValidation<E>(S: Semigroup<E>): Alt2C<URI, E>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

getApplicativeIOValidation​

The default ApplicativePar instance returns the first error, if you want to get all errors you need to provide a way to concatenate them via a Semigroup.

See getApplicativeValidation.

Signature​

export declare function getApplicativeIOValidation<E>(S: Semigroup<E>): Applicative2C<URI, E>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

getOrElse​

Signature​

export declare const getOrElse: <E, A>(onLeft: (e: E) => IO<A>) => (ma: IOEither<E, A>) => IO<A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

getOrElseW​

Less strict version of getOrElse.

The W suffix (short for Widening) means that the handler return type will be merged.

Signature​

export declare const getOrElseW: <E, B>(onLeft: (e: E) => IO<B>) => <A>(ma: IOEither<E, A>) => IO<A | B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

mapBoth​

Returns a IOEither whose failure and success channels have been mapped by the specified pair of functions, f and g.

Signature​

export declare const mapBoth: {
  <E, G, A, B>(f: (e: E) => G, g: (a: A) => B): (self: IOEither<E, A>) => IOEither<G, B>
  <E, A, G, B>(self: IOEither<E, A>, f: (e: E) => G, g: (a: A) => B): IOEither<G, B>
}

Details​

  • Added in 0.1.0

Example​

import * as IOEither from '@fp-tx/core/IOEither'
import * as Either from '@fp-tx/core/Either'

const f = (s: string) => new Error(s)
const g = (n: number) => n * 2

assert.deepStrictEqual(IOEither.mapBoth(IOEither.right(1), f, g)(), Either.right(2))
assert.deepStrictEqual(IOEither.mapBoth(IOEither.left('err'), f, g)(), Either.left(new Error('err')))

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

mapError​

Returns a IOEither with its error channel mapped using the specified function.

Signature​

export declare const mapError: {
  <E, G>(f: (e: E) => G): <A>(self: IOEither<E, A>) => IOEither<G, A>
  <E, A, G>(self: IOEither<E, A>, f: (e: E) => G): IOEither<G, A>
}

Details​

  • Added in 0.1.0

Example​

import * as IOEither from '@fp-tx/core/IOEither'
import * as Either from '@fp-tx/core/Either'

const f = (s: string) => new Error(s)

assert.deepStrictEqual(IOEither.mapError(IOEither.right(1), f)(), Either.right(1))
assert.deepStrictEqual(IOEither.mapError(IOEither.left('err'), f)(), Either.left(new Error('err')))

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

orElse​

Signature​

export declare const orElse: <E1, A, E2>(onLeft: (e: E1) => IOEither<E2, A>) => (ma: IOEither<E1, A>) => IOEither<E2, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

orElseFirstIOK​

Signature​

export declare const orElseFirstIOK: <E, B>(onLeft: (e: E) => IO<B>) => <A>(ma: IOEither<E, A>) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

orElseW​

Less strict version of orElse.

The W suffix (short for Widening) means that the return types will be merged.

Signature​

export declare const orElseW: <E1, E2, B>(
  onLeft: (e: E1) => IOEither<E2, B>,
) => <A>(ma: IOEither<E1, A>) => IOEither<E2, A | B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

orLeft​

Signature​

export declare const orLeft: <E1, E2>(onLeft: (e: E1) => IO<E2>) => <A>(fa: IOEither<E1, A>) => IOEither<E2, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

tapError​

Returns an effect that effectfully "peeks" at the failure of this effect.

Signature​

export declare const tapError: {
  <E1, E2, _>(onLeft: (e: E1) => IOEither<E2, _>): <A>(self: IOEither<E1, A>) => IOEither<E1 | E2, A>
  <E1, A, E2, _>(self: IOEither<E1, A>, onLeft: (e: E1) => IOEither<E2, _>): IOEither<E1 | E2, A>
}

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Filtering​

filterOrElse​

Signature​

export declare const filterOrElse: {
  <E, A, B extends A>(refinement: Refinement<A, B>, onFalse: (a: A) => E): (ma: IOEither<E, A>) => IOEither<E, B>
  <E, A>(predicate: Predicate<A>, onFalse: (a: A) => E): <B extends A>(mb: IOEither<E, B>) => IOEither<E, B>
  <E, A>(predicate: Predicate<A>, onFalse: (a: A) => E): (ma: IOEither<E, A>) => IOEither<E, A>
}

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

filterOrElseW​

Less strict version of filterOrElse.

The W suffix (short for Widening) means that the error types will be merged.

Signature​

export declare const filterOrElseW: {
  <A, B extends A, E2>(
    refinement: Refinement<A, B>,
    onFalse: (a: A) => E2,
  ): <E1>(ma: IOEither<E1, A>) => IOEither<E1 | E2, B>
  <A, E2>(
    predicate: Predicate<A>,
    onFalse: (a: A) => E2,
  ): <E1, B extends A>(mb: IOEither<E1, B>) => IOEither<E1 | E2, B>
  <A, E2>(predicate: Predicate<A>, onFalse: (a: A) => E2): <E1>(ma: IOEither<E1, A>) => IOEither<E1 | E2, A>
}

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

getCompactable​

Signature​

export declare const getCompactable: <E>(M: Monoid<E>) => Compactable2C<'IOEither', E>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

getFilterable​

Signature​

export declare function getFilterable<E>(M: Monoid<E>): Filterable2C<URI, E>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Instance Methods​

chainRec​

Signature​

export declare const chainRec: ChainRec2<URI>['chainRec']

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2022-present Jacob Alford

Interop​

tryCatch​

Constructs a new IOEither from a function that performs a side effect and might throw

See also tryCatchK.

Signature​

export declare const tryCatch: <E, A>(f: LazyArg<A>, onThrow: (reason: unknown) => E) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

tryCatchK​

Converts a function that may throw to one returning a IOEither.

Signature​

export declare const tryCatchK: <A extends readonly unknown[], B, E>(
  f: (...a: A) => B,
  onThrow: (reason: unknown) => E,
) => (...a: A) => IOEither<E, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Legacy​

bimap​

Alias of mapBoth.

Signature​

export declare const bimap: <E, G, A, B>(f: (e: E) => G, g: (a: A) => B) => (fa: IOEither<E, A>) => IOEither<G, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

chain​

Alias of flatMap.

Signature​

export declare const chain: <E, A, B>(f: (a: A) => IOEither<E, B>) => (ma: IOEither<E, A>) => IOEither<E, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

chainEitherK​

Alias of flatMapEither.

Signature​

export declare const chainEitherK: <E, A, B>(f: (a: A) => E.Either<E, B>) => (ma: IOEither<E, A>) => IOEither<E, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

chainEitherKW​

Alias of flatMapEither.

Signature​

export declare const chainEitherKW: <E2, A, B>(
  f: (a: A) => Either<E2, B>,
) => <E1>(ma: IOEither<E1, A>) => IOEither<E1 | E2, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

chainFirst​

Alias of tap.

Signature​

export declare const chainFirst: <E, A, B>(f: (a: A) => IOEither<E, B>) => (ma: IOEither<E, A>) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

chainFirstEitherK​

Alias of tapEither.

Signature​

export declare const chainFirstEitherK: <A, E, B>(f: (a: A) => E.Either<E, B>) => (ma: IOEither<E, A>) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

chainFirstEitherKW​

Alias of tapEither.

The W suffix (short for Widening) means that the error types will be merged.

Signature​

export declare const chainFirstEitherKW: <A, E2, B>(
  f: (a: A) => E.Either<E2, B>,
) => <E1>(ma: IOEither<E1, A>) => IOEither<E1 | E2, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

chainFirstIOK​

Alias of tapIO.

Signature​

export declare const chainFirstIOK: <A, B>(f: (a: A) => I.IO<B>) => <E>(first: IOEither<E, A>) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

chainFirstW​

Alias of tap.

Signature​

export declare const chainFirstW: <E2, A, B>(
  f: (a: A) => IOEither<E2, B>,
) => <E1>(ma: IOEither<E1, A>) => IOEither<E1 | E2, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

chainIOK​

Alias of flatMapIO.

Signature​

export declare const chainIOK: <A, B>(f: (a: A) => I.IO<B>) => <E>(first: IOEither<E, A>) => IOEither<E, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

chainOptionK​

Use flatMapOption.

Signature​

export declare const chainOptionK: <E>(
  onNone: LazyArg<E>,
) => <A, B>(f: (a: A) => Option<B>) => (ma: IOEither<E, A>) => IOEither<E, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

chainOptionKW​

Use flatMapOption.

Signature​

export declare const chainOptionKW: <E2>(
  onNone: LazyArg<E2>,
) => <A, B>(f: (a: A) => Option<B>) => <E1>(ma: IOEither<E1, A>) => IOEither<E1 | E2, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

chainW​

Alias of flatMap.

Signature​

export declare const chainW: <E2, A, B>(
  f: (a: A) => IOEither<E2, B>,
) => <E1>(ma: IOEither<E1, A>) => IOEither<E1 | E2, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

fromOptionK​

Use liftOption.

Signature​

export declare const fromOptionK: <E>(
  onNone: LazyArg<E>,
) => <A extends ReadonlyArray<unknown>, B>(f: (...a: A) => Option<B>) => (...a: A) => IOEither<E, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

mapLeft​

Alias of mapError.

Signature​

export declare const mapLeft: <E, G>(f: (e: E) => G) => <A>(fa: IOEither<E, A>) => IOEither<G, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

orElseFirst​

Alias of tapError.

Signature​

export declare const orElseFirst: <E, B>(onLeft: (e: E) => IOEither<E, B>) => <A>(ma: IOEither<E, A>) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

orElseFirstW​

Alias of tapError.

Signature​

export declare const orElseFirstW: <E1, E2, B>(
  onLeft: (e: E1) => IOEither<E2, B>,
) => <A>(ma: IOEither<E1, A>) => IOEither<E1 | E2, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Lifting​

fromEitherK​

Signature​

export declare const fromEitherK: <E, A extends ReadonlyArray<unknown>, B>(
  f: (...a: A) => E.Either<E, B>,
) => (...a: A) => IOEither<E, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

fromIOK​

Signature​

export declare const fromIOK: <A extends ReadonlyArray<unknown>, B>(
  f: (...a: A) => I.IO<B>,
) => <E = never>(...a: A) => IOEither<E, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

fromPredicate​

Signature​

export declare const fromPredicate: {
  <E, A, B extends A>(refinement: Refinement<A, B>, onFalse: (a: A) => E): (a: A) => IOEither<E, B>
  <E, A>(predicate: Predicate<A>, onFalse: (a: A) => E): <B extends A>(b: B) => IOEither<E, B>
  <E, A>(predicate: Predicate<A>, onFalse: (a: A) => E): (a: A) => IOEither<E, A>
}

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

liftNullable​

Signature​

export declare const liftNullable: <A extends ReadonlyArray<unknown>, B, E>(
  f: (...a: A) => B | null | undefined,
  onNullable: (...a: A) => E,
) => (...a: A) => IOEither<E, NonNullable<B>>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

liftOption​

Signature​

export declare const liftOption: <A extends ReadonlyArray<unknown>, B, E>(
  f: (...a: A) => Option<B>,
  onNone: (...a: A) => E,
) => (...a: A) => IOEither<E, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Mapping​

as​

Maps the Right value of this IOEither to the specified constant value.

Signature​

export declare const as: {
  <A>(a: A): <E, _>(self: IOEither<E, _>) => IOEither<E, A>
  <E, _, A>(self: IOEither<E, _>, a: A): IOEither<E, A>
}

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

asUnit​

Maps the Right value of this IOEither to the void constant value.

Signature​

export declare const asUnit: <E, _>(self: IOEither<E, _>) => IOEither<E, void>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

flap​

Signature​

export declare const flap: <A>(a: A) => <E, B>(fab: IOEither<E, (a: A) => B>) => IOEither<E, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

map​

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.

Signature​

export declare const map: <A, B>(f: (a: A) => B) => <E>(fa: IOEither<E, A>) => IOEither<E, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Model​

IOEither​

Signature​

export interface IOEither<E, A> extends IO<Either<E, A>> {}

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Pattern matching​

fold​

Alias of matchE.

Signature​

export declare const fold: <E, A, B>(
  onLeft: (e: E) => I.IO<B>,
  onRight: (a: A) => I.IO<B>,
) => (ma: IOEither<E, A>) => I.IO<B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

foldW​

Alias of matchEW.

Signature​

export declare const foldW: <E, B, A, C>(
  onLeft: (e: E) => I.IO<B>,
  onRight: (a: A) => I.IO<C>,
) => (ma: IOEither<E, A>) => I.IO<B | C>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

match​

Signature​

export declare const match: <E, B, A>(onLeft: (e: E) => B, onRight: (a: A) => B) => (ma: IOEither<E, A>) => IO<B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

matchE​

The E suffix (short for Effect) means that the handlers return an effect (IO).

Signature​

export declare const matchE: <E, A, B>(
  onLeft: (e: E) => IO<B>,
  onRight: (a: A) => IO<B>,
) => (ma: IOEither<E, A>) => IO<B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

matchEW​

Less strict version of matchE.

The W suffix (short for Widening) means that the handler return types will be merged.

Signature​

export declare const matchEW: <E, B, A, C>(
  onLeft: (e: E) => IO<B>,
  onRight: (a: A) => IO<C>,
) => (ma: IOEither<E, A>) => IO<B | C>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

matchW​

Less strict version of match.

The W suffix (short for Widening) means that the handler return types will be merged.

Signature​

export declare const matchW: <E, B, A, C>(
  onLeft: (e: E) => B,
  onRight: (a: A) => C,
) => (ma: IOEither<E, A>) => IO<B | C>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Sequencing​

flatMap​

Signature​

export declare const flatMap: {
  <A, E2, B>(f: (a: A) => IOEither<E2, B>): <E1>(ma: IOEither<E1, A>) => IOEither<E1 | E2, B>
  <E1, A, E2, B>(ma: IOEither<E1, A>, f: (a: A) => IOEither<E2, B>): IOEither<E1 | E2, B>
}

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

flatMapEither​

Signature​

export declare const flatMapEither: {
  <A, E2, B>(f: (a: A) => E.Either<E2, B>): <E1>(self: IOEither<E1, A>) => IOEither<E1 | E2, B>
  <E1, A, E2, B>(self: IOEither<E1, A>, f: (a: A) => E.Either<E2, B>): IOEither<E1 | E2, B>
}

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

flatMapIO​

Signature​

export declare const flatMapIO: {
  <A, B>(f: (a: A) => IO<B>): <E>(self: IOEither<E, A>) => IOEither<E, B>
  <E, A, B>(self: IOEither<E, A>, f: (a: A) => IO<B>): IOEither<E, B>
}

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

flatMapNullable​

Signature​

export declare const flatMapNullable: {
  <A, B, E2>(
    f: (a: A) => B | null | undefined,
    onNullable: (a: A) => E2,
  ): <E1>(self: IOEither<E1, A>) => IOEither<E2 | E1, NonNullable<B>>
  <E1, A, B, E2>(
    self: IOEither<E1, A>,
    f: (a: A) => B | null | undefined,
    onNullable: (a: A) => E2,
  ): IOEither<E1 | E2, NonNullable<B>>
}

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

flatMapOption​

Signature​

export declare const flatMapOption: {
  <A, B, E2>(f: (a: A) => Option<B>, onNone: (a: A) => E2): <E1>(self: IOEither<E1, A>) => IOEither<E2 | E1, B>
  <E1, A, B, E2>(self: IOEither<E1, A>, f: (a: A) => Option<B>, onNone: (a: A) => E2): IOEither<E1 | E2, B>
}

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

flatten​

Signature​

export declare const flatten: <E, A>(mma: IOEither<E, IOEither<E, A>>) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

flattenW​

Less strict version of flatten.

The W suffix (short for Widening) means that the error types will be merged.

Signature​

export declare const flattenW: <E1, E2, A>(mma: IOEither<E1, IOEither<E2, A>>) => IOEither<E1 | E2, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Traversing​

sequenceArray​

Equivalent to ReadonlyArray#sequence(Applicative).

Signature​

export declare const sequenceArray: <E, A>(arr: ReadonlyArray<IOEither<E, A>>) => IOEither<E, ReadonlyArray<A>>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

sequenceSeqArray​

Equivalent to ReadonlyArray#sequence(ApplicativeSeq).

Signature​

export declare const sequenceSeqArray: <E, A>(arr: ReadonlyArray<IOEither<E, A>>) => IOEither<E, ReadonlyArray<A>>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

traverseArray​

Equivalent to ReadonlyArray#traverse(Applicative).

Signature​

export declare const traverseArray: <A, E, B>(
  f: (a: A) => IOEither<E, B>,
) => (as: readonly A[]) => IOEither<E, readonly B[]>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

traverseArrayWithIndex​

Equivalent to ReadonlyArray#traverseWithIndex(Applicative).

Signature​

export declare const traverseArrayWithIndex: <A, E, B>(
  f: (index: number, a: A) => IOEither<E, B>,
) => (as: ReadonlyArray<A>) => IOEither<E, ReadonlyArray<B>>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

traverseReadonlyArrayWithIndex​

Equivalent to ReadonlyArray#traverseWithIndex(ApplicativePar).

Signature​

export declare const traverseReadonlyArrayWithIndex: <A, E, B>(
  f: (index: number, a: A) => IOEither<E, B>,
) => (as: readonly A[]) => IOEither<E, readonly B[]>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

traverseReadonlyArrayWithIndexSeq​

Equivalent to ReadonlyArray#traverseWithIndex(ApplicativeSeq).

Signature​

export declare const traverseReadonlyArrayWithIndexSeq: <A, E, B>(
  f: (index: number, a: A) => IOEither<E, B>,
) => (as: readonly A[]) => IOEither<E, readonly B[]>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

traverseReadonlyNonEmptyArrayWithIndex​

Equivalent to ReadonlyNonEmptyArray#traverseWithIndex(ApplicativePar).

Signature​

export declare const traverseReadonlyNonEmptyArrayWithIndex: <A, E, B>(
  f: (index: number, a: A) => IOEither<E, B>,
) => (as: ReadonlyNonEmptyArray<A>) => IOEither<E, ReadonlyNonEmptyArray<B>>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

traverseReadonlyNonEmptyArrayWithIndexSeq​

Equivalent to ReadonlyNonEmptyArray#traverseWithIndex(ApplicativeSeq).

Signature​

export declare const traverseReadonlyNonEmptyArrayWithIndexSeq: <A, E, B>(
  f: (index: number, a: A) => IOEither<E, B>,
) => (as: ReadonlyNonEmptyArray<A>) => IOEither<E, ReadonlyNonEmptyArray<B>>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

traverseSeqArray​

Equivalent to ReadonlyArray#traverse(ApplicativeSeq).

Signature​

export declare const traverseSeqArray: <A, E, B>(
  f: (a: A) => IOEither<E, B>,
) => (as: readonly A[]) => IOEither<E, readonly B[]>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

traverseSeqArrayWithIndex​

Equivalent to ReadonlyArray#traverseWithIndex(ApplicativeSeq).

Signature​

export declare const traverseSeqArrayWithIndex: <A, E, B>(
  f: (index: number, a: A) => IOEither<E, B>,
) => (as: ReadonlyArray<A>) => IOEither<E, ReadonlyArray<B>>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Type lambdas​

URI​

Signature​

export type URI = typeof URI

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

URI​

Signature​

export declare const URI = 'IOEither'

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Utilities​

ApT​

Signature​

export declare const ApT: IOEither<never, readonly []>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

Applicative​

Use ApplicativePar instead

Signature​

export declare const Applicative: Applicative2<URI>

Details​

  • Added in 0.1.0
  • Deprecated

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

ap​

Signature​

export declare const ap: <E, A>(fa: IOEither<E, A>) => <B>(fab: IOEither<E, (a: A) => B>) => IOEither<E, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

apFirst​

Combine two effectful actions, keeping only the result of the first.

Signature​

export declare const apFirst: <E, B>(second: IOEither<E, B>) => <A>(first: IOEither<E, A>) => IOEither<E, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

apFirstW​

Less strict version of apFirst.

The W suffix (short for Widening) means that the error types will be merged.

Signature​

export declare const apFirstW: <E2, B>(
  second: IOEither<E2, B>,
) => <E1, A>(first: IOEither<E1, A>) => IOEither<E1 | E2, A>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

apSecond​

Combine two effectful actions, keeping only the result of the second.

Signature​

export declare const apSecond: <E, B>(second: IOEither<E, B>) => <A>(first: IOEither<E, A>) => IOEither<E, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

apSecondW​

Less strict version of apSecond.

The W suffix (short for Widening) means that the error types will be merged.

Signature​

export declare const apSecondW: <E2, B>(
  second: IOEither<E2, B>,
) => <E1, A>(first: IOEither<E1, A>) => IOEither<E1 | E2, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

apW​

Less strict version of ap.

The W suffix (short for Widening) means that the error types will be merged.

Signature​

export declare const apW: <E2, A>(
  fa: IOEither<E2, A>,
) => <E1, B>(fab: IOEither<E1, (a: A) => B>) => IOEither<E1 | E2, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

bracket​

Make sure that a resource is cleaned up in the event of an exception (). The release action is called regardless of whether the body action throws () or returns.

(*) i.e. returns a Left

Signature​

export declare const bracket: <E, A, B>(
  acquire: IOEither<E, A>,
  use: (a: A) => IOEither<E, B>,
  release: (a: A, e: E.Either<E, B>) => IOEither<E, void>,
) => IOEither<E, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

bracketW​

Less strict version of bracket.

The W suffix (short for Widening) means that the error types will be merged.

Signature​

export declare const bracketW: <E1, A, E2, B, E3>(
  acquire: IOEither<E1, A>,
  use: (a: A) => IOEither<E2, B>,
  release: (a: A, e: E.Either<E2, B>) => IOEither<E3, void>,
) => IOEither<E1 | E2 | E3, B>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

do​

Signature​

export declare const do_: <MA extends IOEitherIterable<any, any>, A>(
  yieldFunction: (unwrap: <E, A>(ma: IOEither<E, A>) => IOEitherIterable<E, A>) => Generator<MA, A>,
) => IOEither<MA extends IOEitherIterable<infer E, any> ? E : never, A>

getApplyMonoid​

Use getApplicativeMonoid instead.

Signature​

export declare const getApplyMonoid: <E, A>(M: Monoid<A>) => Monoid<IOEither<E, A>>

Details​

  • Added in 0.1.0
  • Deprecated

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

getApplySemigroup​

Use getApplySemigroup instead.

Signature​

export declare const getApplySemigroup: <E, A>(S: Semigroup<A>) => Semigroup<IOEither<E, A>>

Details​

  • Added in 0.1.0
  • Deprecated

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

getIOValidation​

Use getApplicativeIOValidation and getAltIOValidation.

Signature​

export declare function getIOValidation<E>(
  SE: Semigroup<E>,
): Monad2C<URI, E> & Bifunctor2<URI> & Alt2C<URI, E> & MonadIO2C<URI, E> & MonadThrow2C<URI, E>

Details​

  • Added in 0.1.0
  • Deprecated

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

getSemigroup​

Use getApplySemigroup instead.

Signature​

export declare const getSemigroup: <E, A>(S: Semigroup<A>) => Semigroup<IOEither<E, A>>

Details​

  • Added in 0.1.0
  • Deprecated

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

ioEither​

This instance is deprecated, use small, specific instances instead. For example if a function needs a Functor instance, pass IOE.Functor instead of IOE.ioEither (where IOE is from import IOE from 'fp-ts/IOEither')

Signature​

export declare const ioEither: Monad2<URI> & Bifunctor2<URI> & Alt2<URI> & MonadIO2<URI> & MonadThrow2<URI>

Details​

  • Added in 0.1.0
  • Deprecated

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

let​

Signature​

export declare const let_: <N extends string, A, B>(
  name: Exclude<N, keyof A>,
  f: (a: A) => B,
) => <E>(fa: IOEither<E, A>) => IOEither<E, { readonly [K in N | keyof A]: K extends keyof A ? A[K] : B }>

swap​

Signature​

export declare const swap: <E, A>(ma: IOEither<E, A>) => IOEither<A, E>

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti

throwError​

Signature​

export declare const throwError: MonadThrow2<URI>['throwError']

Details​

  • Added in 0.1.0

License​

  • MIT – Copyright (c) 2017-present Giulio Canti