Invariant.ts overview

The Invariant typeclass is a higher-order abstraction over types that allow mapping the contents of a type in both directions. It is similar to the Covariant typeclass but provides an imap opration, which allows transforming a value in both directions. This typeclass is useful when dealing with data types that can be converted to and from some other types. The imap operation provides a way to convert such data types to other types that they can interact with while preserving their invariants.

Since v0.24.0

do notation

bindTo

Signature

declare const bindTo: <F extends TypeLambda>(
  F: Invariant<F>
) => {
  <N extends string>(name: N): <R, O, E, A>(self: Kind<F, R, O, E, A>) => Kind<F, R, O, E, { [K in N]: A }>
  <R, O, E, A, N extends string>(self: Kind<F, R, O, E, A>, name: N): Kind<F, R, O, E, { [K in N]: A }>
}

Source

Since v0.24.0

type class

Invariant (interface)

Signature

export interface Invariant<F extends TypeLambda> extends TypeClass<F> {
  readonly imap: {
    <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>
  }
}

Source

Since v0.24.0

utils

imapComposition

Returns a default ternary imap composition.

Signature

declare const imapComposition: <F extends TypeLambda, G extends TypeLambda>(
  F: Invariant<F>,
  G: Invariant<G>
) => <FR, FO, FE, GR, GO, GE, A, B>(
  self: Kind<F, FR, FO, FE, Kind<G, GR, GO, GE, A>>,
  to: (a: A) => B,
  from: (b: B) => A
) => Kind<F, FR, FO, FE, Kind<G, GR, GO, GE, B>>

Source

Since v0.24.0

tupled

Convert a value in a singleton array in a given effect.

Signature

declare const tupled: <F extends TypeLambda>(
  F: Invariant<F>
) => <R, O, E, A>(self: Kind<F, R, O, E, A>) => Kind<F, R, O, E, [A]>

Source

Since v0.24.0