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core

Contravariant overview

Added in v1.0.0

Table of contents

type class

Contravariant (interface)

Signature

export interface Contravariant<F extends TypeLambda> extends Invariant<F> {
  readonly contramap: {
    <B, A>(f: (b: B) => A): <R, O, E>(self: Kind<F, R, O, E, A>) => Kind<F, R, O, E, B>
    <R, O, E, A, B>(self: Kind<F, R, O, E, A>, f: (b: B) => A): Kind<F, R, O, E, B>
  }
}

Added in v1.0.0

utils

contramapComposition

Composing two contravariant functors yields a Covariant functor.

Returns a default binary map composition.

Signature

export declare const contramapComposition: <F extends TypeLambda, G extends TypeLambda>(
  F: Contravariant<F>,
  G: Contravariant<G>
) => <FR, FO, FE, GR, GO, GE, A, B>(
  self: Kind<F, FR, FO, FE, Kind<G, GR, GO, GE, A>>,
  f: (a: A) => B
) => Kind<F, FR, FO, FE, Kind<G, GR, GO, GE, B>>

Added in v1.0.0

imap

Returns a default imap implementation.

Signature

export declare const imap: <F extends TypeLambda>(
  contramap: <R, O, E, A, B>(self: Kind<F, R, O, E, A>, f: (b: B) => A) => Kind<F, R, O, E, B>
) => {
  <A, B>(to: (a: A) => B, from: (b: B) => A): <R, O, E>(self: Kind<F, R, O, E, A>) => Kind<F, R, O, E, B>
  <R, O, E, A, B>(self: Kind<F, R, O, E, A>, to: (a: A) => B, from: (b: B) => A): Kind<F, R, O, E, B>
}

Added in v1.0.0