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fp-ts-indexed-monad

IxState overview

IxState (Indexed State) is a derivation of State, that may have polymorphic states; The input may be of a different type than the output.

State changes are kept track of by the generics I, O, X and Z.

  • I indicates the current input state
  • O indicates the current output state
  • X indicates the next input state
  • Z indicates the next output state

When composing IxState where the indexes are polymorhpic, functions ixchain and ixap can be used to compose <I, O> with <O, Z> to return <I, Z>.

Intuitively this is function composition on the indexes.

IxState is derived by applying the Identity monad to the transformer IxStateT.

Added in v2.10.0

Table of contents

Apply

ap

Signature

export declare const ap: <I, A>(
  fa: IxStateT.IxStateT1<'Identity', I, I, A>
) => <B>(fab: IxStateT.IxStateT1<'Identity', I, I, (a: A) => B>) => IxStateT.IxStateT1<'Identity', I, I, B>

Added in v2.10.0

apFirst

Signature

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

Added in v2.10.0

apSecond

Signature

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

Added in v2.10.0

Chain

chain

Signature

export declare const chain: <I, A, B>(
  f: (a: A) => IxStateT.IxStateT1<'Identity', I, I, B>
) => (fa: IxStateT.IxStateT1<'Identity', I, I, A>) => IxStateT.IxStateT1<'Identity', I, I, B>

Added in v2.10.0

chainFirst

Signature

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

Added in v2.10.0

Functor

flap

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 flap: <A>(a: A) => <R, E, B>(fab: IxState<R, E, (a: A) => B>) => IxState<R, E, B>

Added in v2.10.0

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
) => <I, O>(fa: IxStateT.IxStateT1<'Identity', I, O, A>) => IxStateT.IxStateT1<'Identity', I, O, B>

Added in v2.10.0

IxApply

ixap

Apply a function to an argument under a type constructor.

Signature

export declare const ixap: <O, Z, A>(
  fa: IxStateT.IxStateT1<'Identity', O, Z, A>
) => <I, B>(fab: IxStateT.IxStateT1<'Identity', I, O, (a: A) => B>) => IxStateT.IxStateT1<'Identity', I, Z, B>

Added in v2.10.0

ixapFirst

Signature

export declare const ixapFirst: <O, Z, B>(
  second: IxState<O, Z, B>
) => <I, A>(first: IxState<I, O, A>) => IxState<I, Z, A>

Added in v2.10.0

ixapSecond

Signature

export declare const ixapSecond: <I, O, Z, A, B>(
  second: IxState<O, Z, B>
) => (first: IxState<I, O, A>) => IxState<I, Z, B>

Added in v2.10.0

IxChain

ixchain

Composes computations in sequence, using the return value of one computation to determine the next computation.

Signature

export declare const ixchain: <O, Z, A, B>(
  f: (a: A) => IxStateT.IxStateT1<'Identity', O, Z, B>
) => <I>(fa: IxStateT.IxStateT1<'Identity', I, O, A>) => IxStateT.IxStateT1<'Identity', I, Z, B>

Added in v2.10.0

ixchainFirst

Signature

export declare const ixchainFirst: <I, O, Z, A, B>(
  f: (a: A) => IxState<O, Z, B>
) => (first: IxState<I, O, A>) => IxState<I, Z, A>

Added in v2.10.0

IxFunctor

ixflap

Signature

export declare const ixflap: <A>(a: A) => <I, O, B>(fab: IxState<I, O, (a: A) => B>) => IxState<I, O, B>

Added in v2.10.0

ixmap

Signature

export declare const ixmap: <A, B>(
  f: (a: A) => B
) => <I, O>(fa: IxStateT.IxStateT1<'Identity', I, O, A>) => IxStateT.IxStateT1<'Identity', I, O, B>

Added in v2.10.0

IxPointed

ixof

Signature

export declare const ixof: <I, A>(a: A) => IxState<I, I, A>

Added in v2.10.0

Model

IxState (interface)

Signature

export interface IxState<I, O, A> {
  (i: I): [A, O]
}

Added in v2.10.0

URI

Signature

export declare const URI: 'IxState'

Added in v2.10.0

URI (type alias)

Signature

export type URI = typeof URI

Added in v2.10.0

Pointed

of

Signature

export declare const of: <E, A>(a: A) => IxState<E, E, A>

Added in v2.10.0

combinators

local

Changes the value of the local context during the execution of the action ma (similar to Contravariant’s contramap).

Signature

export declare const local: <I, X>(
  f: (x: X) => I
) => <O, A>(fa: IxStateT.IxStateT1<'Identity', I, O, A>) => IxStateT.IxStateT1<'Identity', X, O, A>

Added in v2.10.0

constructors

fromState

Signature

export declare const fromState: <I, A>(fa: State<I, A>) => IxState<I, I, A>

Added in v2.10.0

get

Signature

export declare const get: <I>() => IxStateT.IxStateT1<'Identity', I, I, I>

Added in v2.10.0

gets

Signature

export declare const gets: <I, A>(f: (i: I) => A) => IxStateT.IxStateT1<'Identity', I, I, A>

Added in v2.10.0

ixmodify

Signature

export declare const ixmodify: <I, O>(f: (i: I) => O) => IxState<I, O, void>

Added in v2.10.0

put

Signature

export declare const put: <I>(fi: I) => IxState<I, I, void>

Added in v2.10.0

destructors

evaluate

Signature

export declare const evaluate: <I>(i: I) => <O, A>(fa: IxStateT.IxStateT1<'Identity', I, O, A>) => A

Added in v2.10.0

ixexecute

Signature

export declare const ixexecute: <I>(i: I) => <O, A>(fa: IxStateT.IxStateT1<'Identity', I, O, A>) => O

Added in v2.10.0

toState

Signature

export declare const toState: <I, A>(fa: IxState<I, I, A>) => State<I, A>

Added in v2.10.0

instances

Apply

Signature

export declare const Apply: Apply2<'IxState'>

Added in v2.10.0

Chain

Signature

export declare const Chain: Chain2<'IxState'>

Added in v2.10.0

Functor

Signature

export declare const Functor: Functor3<'IxState'>

Added in v2.10.0

IxApplicative

Signature

export declare const IxApplicative: IxApplicative3<'IxState'>

Added in v2.10.0

IxApply

Signature

export declare const IxApply: IxApply3<'IxState'>

Added in v2.10.0

IxChain

Signature

export declare const IxChain: IxChain3<'IxState'>

Added in v2.10.0

IxFunctor

Signature

export declare const IxFunctor: IxFunctor3<'IxState'>

Added in v2.10.0

IxMonad

Signature

export declare const IxMonad: IxMonad3<'IxState'>

Added in v2.10.0

IxPointed

Signature

export declare const IxPointed: IxPointed3<'IxState'>

Added in v2.10.0

Monad

Signature

export declare const Monad: Monad2<'IxState'>

Added in v2.10.0

Pointed

Signature

export declare const Pointed: Pointed2<'IxState'>

Added in v2.10.0

utils

Do

Signature

export declare const Do: <I>() => IxState<I, I, {}>

Added in v2.10.0

apS

Signature

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

Added in v2.10.0

bind

Signature

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

Added in v2.10.0

bindTo

Signature

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

Added in v2.10.0

discard

Do-notation combinator for discarding the result of a computation rather than binding it to a name. It is simply an alias for chainFirst

Signature

export declare const discard: <A, E, B>(f: (a: A) => IxState<E, E, B>) => (first: IxState<E, E, A>) => IxState<E, E, A>

Added in v2.10.0

ixDo

Signature

export declare const ixDo: <I>() => IxState<I, I, {}>

Added in v2.10.0

ixapS

Signature

export declare const ixapS: <N, A, O, S, B>(
  name: Exclude<N, keyof A>,
  fb: IxState<O, S, B>
) => <First, O>(fa: IxState<First, O, A>) => IxState<First, S, { [K in N | keyof A]: K extends keyof A ? A[K] : B }>

Added in v2.10.0

ixbind

Signature

export declare const ixbind: <N, A, Second, Third, B>(
  name: Exclude<N, keyof A>,
  f: (a: A) => IxState<Second, Third, B>
) => <First>(
  ma: IxState<First, Second, A>
) => IxState<First, Third, { [K in N | keyof A]: K extends keyof A ? A[K] : B }>

Added in v2.10.0

ixbindTo

Signature

export declare const ixbindTo: <N>(name: N) => <I, O, A>(fa: IxState<I, O, A>) => IxState<I, O, { [K in N]: A }>

Added in v2.10.0

ixdiscard

ixDo-notation combinator for discarding the result of a computation rather than binding it to a name. It is simply an alias for ixchainFirst

Signature

export declare const ixdiscard: <I, O, Z, A, B>(
  f: (a: A) => IxState<O, Z, B>
) => (first: IxState<I, O, A>) => IxState<I, Z, A>

Added in v2.10.0

ixlet

Signature

export declare const ixlet: <N, A, B>(
  name: Exclude<N, keyof A>,
  val: (a: A) => B
) => <I, O>(ma: IxState<I, O, A>) => IxState<I, O, { [K in N | keyof A]: K extends keyof A ? A[K] : B }>

Added in v2.10.2

let

Signature

export declare const let: <N, A, B>(
  name: Exclude<N, keyof A>,
  val: (a: A) => B
) => <I, O>(ma: IxState<I, O, A>) => IxState<I, O, { [K in N | keyof A]: K extends keyof A ? A[K] : B }>

Added in v2.10.2

let_

Signature

export declare const let_: <N, A, B>(
  name: Exclude<N, keyof A>,
  val: (a: A) => B
) => <I, O>(ma: IxState<I, O, A>) => IxState<I, O, { [K in N | keyof A]: K extends keyof A ? A[K] : B }>

Added in v2.10.2