Added in v2.0.0
Wrap a value into the type constructor.
Signature
export declare const of: <E, A>(a: A) => Reader<E, A>
Added in v2.0.0
Apply a function to an argument under a type constructor.
Signature
export declare const ap: <R, A>(fa: Reader<R, A>) => <B>(fab: Reader<R, (a: A) => B>) => Reader<R, B>
Added in v2.0.0
Less strict version of ap
.
Signature
export declare const apW: <Q, A>(fa: Reader<Q, A>) => <R, B>(fab: Reader<R, (a: A) => B>) => Reader<Q & R, B>
Added in v2.8.0
Signature
export declare const id: <A>() => Reader<A, A>
Added in v2.0.0
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) => <R>(fa: Reader<R, A>) => Reader<R, B>
Added in v2.0.0
Composes computations in sequence, using the return value of one computation to determine the next computation.
Signature
export declare const chain: <A, R, B>(f: (a: A) => Reader<R, B>) => (ma: Reader<R, A>) => Reader<R, B>
Added in v2.0.0
Less strict version of chain
.
Signature
export declare const chainW: <R, A, B>(f: (a: A) => Reader<R, B>) => <Q>(ma: Reader<Q, A>) => Reader<Q & R, B>
Added in v2.6.0
Signature
export declare const promap: <E, A, D, B>(f: (d: D) => E, g: (a: A) => B) => (fbc: Reader<E, A>) => Reader<D, B>
Added in v2.0.0
Signature
export declare const compose: <A, B>(ab: Reader<A, B>) => <C>(bc: Reader<B, C>) => Reader<A, C>
Added in v2.0.0
Combine two effectful actions, keeping only the result of the first.
Derivable from Apply
.
Signature
export declare const apFirst: <R, B>(fb: Reader<R, B>) => <A>(fa: Reader<R, A>) => Reader<R, A>
Added in v2.0.0
Combine two effectful actions, keeping only the result of the second.
Derivable from Apply
.
Signature
export declare const apSecond: <R, B>(fb: Reader<R, B>) => <A>(fa: Reader<R, A>) => Reader<R, B>
Added in v2.0.0
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
.
Signature
export declare const chainFirst: <A, R, B>(f: (a: A) => Reader<R, B>) => (ma: Reader<R, A>) => Reader<R, A>
Added in v2.0.0
Derivable from Monad
.
Signature
export declare const flatten: <R, A>(mma: Reader<R, Reader<R, A>>) => Reader<R, A>
Added in v2.0.0
Changes the value of the local context during the execution of the action ma
(similar to Contravariant
's
contramap
).
Signature
export declare const local: <Q, R>(f: (d: Q) => R) => <A>(ma: Reader<R, A>) => Reader<Q, A>
Added in v2.0.0
Reads the current context
Signature
export declare const ask: <R>() => Reader<R, R>
Added in v2.0.0
Projects a value from the global context in a Reader
Signature
export declare const asks: <R, A>(f: (r: R) => A) => Reader<R, A>
Added in v2.0.0
Signature
export declare const Applicative: Applicative2<'Reader'>
Added in v2.7.0
Signature
export declare const Category: Category2<'Reader'>
Added in v2.7.0
Signature
export declare const Choice: Choice2<'Reader'>
Added in v2.8.3
Signature
export declare const Functor: Functor2<'Reader'>
Added in v2.7.0
Signature
export declare const Monad: Monad2<'Reader'>
Added in v2.7.0
Signature
export declare const Profunctor: Profunctor2<'Reader'>
Added in v2.7.0
Signature
export declare const Strong: Strong2<'Reader'>
Added in v2.8.3
Signature
export declare const URI: 'Reader'
Added in v2.0.0
Signature
export type URI = typeof URI
Added in v2.0.0
Signature
export declare function getMonoid<R, A>(M: Monoid<A>): Monoid<Reader<R, A>>
Added in v2.0.0
Signature
export declare function getSemigroup<R, A>(S: Semigroup<A>): Semigroup<Reader<R, A>>
Added in v2.0.0
Signature
export declare const reader: Monad2<'Reader'> &
Profunctor2<'Reader'> &
Category2<'Reader'> &
Strong2<'Reader'> &
Choice2<'Reader'>
Added in v2.0.0
Signature
export interface Reader<R, A> {
(r: R): A
}
Added in v2.0.0
Signature
export declare const Do: Reader<unknown, {}>
Added in v2.9.0
Signature
export declare const apS: <A, N extends string, R, B>(
name: Exclude<N, keyof A>,
fb: Reader<R, B>
) => (fa: Reader<R, A>) => Reader<R, { [K in N | keyof A]: K extends keyof A ? A[K] : B }>
Added in v2.8.0
Signature
export declare const apSW: <A, N extends string, Q, B>(
name: Exclude<N, keyof A>,
fb: Reader<Q, B>
) => <R>(fa: Reader<R, A>) => Reader<Q & R, { [K in N | keyof A]: K extends keyof A ? A[K] : B }>
Added in v2.8.0
Signature
export declare const bind: <N extends string, A, R, B>(
name: Exclude<N, keyof A>,
f: (a: A) => Reader<R, B>
) => (fa: Reader<R, A>) => Reader<R, { [K in N | keyof A]: K extends keyof A ? A[K] : B }>
Added in v2.8.0
Signature
export declare const bindTo: <N extends string>(name: N) => <R, A>(fa: Reader<R, A>) => Reader<R, { [K in N]: A }>
Added in v2.8.0
Signature
export declare const bindW: <N extends string, A, Q, B>(
name: Exclude<N, keyof A>,
f: (a: A) => Reader<Q, B>
) => <R>(fa: Reader<R, A>) => Reader<Q & R, { [K in N | keyof A]: K extends keyof A ? A[K] : B }>
Added in v2.8.0
this function has the same behavior of A.sequence(R.reader)
but it's stack safe and optimized
Signature
export declare const sequenceArray: <R, A>(arr: readonly Reader<R, A>[]) => Reader<R, readonly A[]>
Example
import * as RA from 'fp-ts/ReadonlyArray'
import { sequenceArray, Reader } from 'fp-ts/Reader'
import { pipe } from 'fp-ts/function'
const add: (x: number) => Reader<{ value: number }, number> = (x) => (config) => x + config.value
const arr = RA.range(0, 100)
assert.deepStrictEqual(
pipe(arr, RA.map(add), sequenceArray)({ value: 3 }),
pipe(
arr,
RA.map((x) => x + 3)
)
)
Added in v2.9.0
this function has the same behavior of A.traverse(R.reader)
but it's stack safe and optimized
Signature
export declare const traverseArray: <R, A, B>(
f: (a: A) => Reader<R, B>
) => (arr: readonly A[]) => Reader<R, readonly B[]>
Example
import * as RA from 'fp-ts/ReadonlyArray'
import { traverseArray, Reader } from 'fp-ts/Reader'
import { pipe } from 'fp-ts/function'
const add: (x: number) => Reader<{ value: number }, number> = (x) => (config) => x + config.value
const arr = RA.range(0, 100)
assert.deepStrictEqual(
pipe(arr, traverseArray(add))({ value: 3 }),
pipe(
arr,
RA.map((x) => x + 3)
)
)
Added in v2.9.0
Signature
export declare const traverseArrayWithIndex: <R, A, B>(
f: (index: number, a: A) => Reader<R, B>
) => (arr: readonly A[]) => Reader<R, readonly B[]>
Added in v2.9.0