fp-ts

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Overview

The Alt type class identifies an associative operation on a type constructor. It is similar to Semigroup, except that it applies to types of kind * -> *, like Array or Option, rather than concrete types like string or number.

Alt instances are required to satisfy the following laws:

  1. Associativity: A.alt(A.alt(fa, ga), ha) = A.alt(fa, A.alt(ga, ha))
  2. Distributivity: A.map(A.alt(fa, ga), ab) = A.alt(A.map(fa, ab), A.map(ga, ab))

Table of contents

Alt (interface)

Signature

export interface Alt<F> extends Functor<F> {
  readonly alt: <A>(fx: HKT<F, A>, fy: HKT<F, A>) => HKT<F, A>
}

Added in v1.0.0

Alt1 (interface)

Signature

export interface Alt1<F extends URIS> extends Functor1<F> {
  readonly alt: <A>(fx: Type<F, A>, fy: Type<F, A>) => Type<F, A>
}

Alt2 (interface)

Signature

export interface Alt2<F extends URIS2> extends Functor2<F> {
  readonly alt: <L, A>(fx: Type2<F, L, A>, fy: Type2<F, L, A>) => Type2<F, L, A>
}

Alt2C (interface)

Signature

export interface Alt2C<F extends URIS2, L> extends Functor2C<F, L> {
  readonly alt: <A>(fx: Type2<F, L, A>, fy: Type2<F, L, A>) => Type2<F, L, A>
}

Alt3 (interface)

Signature

export interface Alt3<F extends URIS3> extends Functor3<F> {
  readonly alt: <U, L, A>(fx: Type3<F, U, L, A>, fy: Type3<F, U, L, A>) => Type3<F, U, L, A>
}

Alt3C (interface)

Signature

export interface Alt3C<F extends URIS3, U, L> extends Functor3C<F, U, L> {
  readonly alt: <A>(fx: Type3<F, U, L, A>, fy: Type3<F, U, L, A>) => Type3<F, U, L, A>
}