# Extract

## extract

Signature

``````export declare const extract: <A>(wa: A) => A
``````

# 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: { <A, _>(self: A, f: (a: A) => _): A; <A, _>(f: (a: A) => _): (self: A) => A }
``````

# constructors

## of

Signature

``````export declare const of: <A>(a: A) => A
``````

# do notation

## Do

Signature

``````export declare const Do: {}
``````

## apS

Signature

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

## bind

Signature

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

## bindTo

Signature

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

## let

Signature

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

# 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: <A>(that: () => A) => (fa: A) => A
``````

## altW

Less strict version of `alt`.

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

Signature

``````export declare const altW: <B>(that: () => B) => <A>(fa: A) => B | A
``````

# folding

## foldMap

Signature

``````export declare const foldMap: <M>(M: Monoid<M>) => <A>(f: (a: A) => M) => (fa: A) => M
``````

## reduce

Signature

``````export declare const reduce: <A, B>(b: B, f: (b: B, a: A) => B) => (fa: A) => B
``````

## reduceRight

Signature

``````export declare const reduceRight: <A, B>(b: B, f: (a: A, b: B) => B) => (fa: A) => B
``````

# instances

## Alt

Signature

``````export declare const Alt: Alt1<'Identity'>
``````

## Applicative

Signature

``````export declare const Applicative: Applicative1<'Identity'>
``````

## Apply

Signature

``````export declare const Apply: Apply1<'Identity'>
``````

## Chain

Signature

``````export declare const Chain: Chain1<'Identity'>
``````

## ChainRec

Signature

``````export declare const ChainRec: ChainRec1<'Identity'>
``````

Signature

``````export declare const Comonad: Comonad1<'Identity'>
``````

## Foldable

Signature

``````export declare const Foldable: Foldable1<'Identity'>
``````

## Functor

Signature

``````export declare const Functor: Functor1<'Identity'>
``````

Signature

``````export declare const Monad: Monad1<'Identity'>
``````

## Pointed

Signature

``````export declare const Pointed: Pointed1<'Identity'>
``````

## Traversable

Signature

``````export declare const Traversable: Traversable1<'Identity'>
``````

## getEq

Signature

``````export declare const getEq: <A>(E: Eq<A>) => Eq<A>
``````

## getShow

Signature

``````export declare const getShow: <A>(S: Show<A>) => Show<A>
``````

# legacy

## chain

Alias of `flatMap`.

Signature

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

## chainFirst

Alias of `tap`

Signature

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

# mapping

## flap

Signature

``````export declare const flap: <A>(a: A) => <B>(fab: (a: A) => B) => B
``````

## 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) => (fa: A) => B
``````

# model

## Identity (type alias)

Signature

``````export type Identity<A> = A
``````

# sequencing

## flatMap

Signature

``````export declare const flatMap: { <A, B>(f: (a: A) => B): (ma: A) => B; <A, B>(ma: A, f: (a: A) => B): B }
``````

## flatten

Signature

``````export declare const flatten: <A>(mma: A) => A
``````

# traversing

## sequence

Signature

``````export declare const sequence: Sequence1<'Identity'>
``````

## traverse

Signature

``````export declare const traverse: PipeableTraverse1<'Identity'>
``````

# type lambdas

## URI

Signature

``````export declare const URI: 'Identity'
``````

## URI (type alias)

Signature

``````export type URI = typeof URI
``````

# utils

## ap

Signature

``````export declare const ap: <A>(fa: A) => <B>(fab: (a: A) => B) => B
``````

## apFirst

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

Signature

``````export declare const apFirst: <B>(second: B) => <A>(first: A) => A
``````

## apSecond

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

Signature

``````export declare const apSecond: <B>(second: B) => <A>(first: A) => B
``````

## duplicate

Signature

``````export declare const duplicate: <A>(ma: A) => A
``````

## extend

Signature

``````export declare const extend: <A, B>(f: (wa: A) => B) => (wa: A) => B
``````

# zone of death

## identity

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

Signature

``````export declare const identity: Monad1<'Identity'> &
Foldable1<'Identity'> &
Traversable1<'Identity'> &
Alt1<'Identity'> &