ContravariantCoyoneda

Decomposition of fi.contramap(k) into its components, as it is frequently convenient to apply k separately from sorting or whatever process with fi, even when B is unknown, which is very common.

This is isomorphic to F as long as F itself is a contravariant functor. The homomorphism from F[A] to ContravariantCoyoneda[F,A] exists even when F is not a contravariant functor.

See ContravariantCoyonedaUsage.scala in the scalaz source tree for an interesting usage demonstration.

As ContravariantCoyoneda(o)(identity).unlift = o, further factoring can occur as follows, for free:

ContravariantCoyoneda(o contramap g)(f).unlift =
  ContravariantCoyoneda(o)(g compose f).unlift

Source: ContravariantCoyoneda.scala
See also: https://hackage.haskell.org/package/kan-extensions-4.0.1/docs/Data-Functor-Contravariant-Coyoneda.html

Linear Supertypes

AnyRef, Any

Type Members

abstract type I

The pivot between fi and k, usually existential.

Abstract Value Members

abstract val fi: F[I]

The underlying value.
abstract val k: (A) ⇒ I

The transformer function, to be lifted into F by run.

Concrete Value Members

final def !=(arg0: Any): Boolean

Definition Classes
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final def ##(): Int

Definition Classes
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final def ==(arg0: Any): Boolean

Definition Classes
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final def asInstanceOf[T0]: T0

Definition Classes
Any
def clone(): AnyRef

Attributes
protected[java.lang]
Definition Classes
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Annotations
@throws( ... )
final def contramap[B](f: (B) ⇒ A): Aux[F, B, I]

Simple function composition.
Simple function composition. Allows map fusion without touching the underlying F.
final def eq(arg0: AnyRef): Boolean

Definition Classes
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def equals(arg0: Any): Boolean

Definition Classes
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def finalize(): Unit

Attributes
protected[java.lang]
Definition Classes
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Annotations
@throws( classOf[java.lang.Throwable] )
final def getClass(): Class[_]

Definition Classes
AnyRef → Any
def hashCode(): Int

Definition Classes
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final def isInstanceOf[T0]: Boolean

Definition Classes
Any
final def ne(arg0: AnyRef): Boolean

Definition Classes
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final def notify(): Unit

Definition Classes
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final def notifyAll(): Unit

Definition Classes
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final def run(implicit F: Contravariant[F]): F[A]

Converts to F[A] given that F is a contravariant.
final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
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def toString(): String

Definition Classes
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final def trans[G[_]](f: ~>[F, G]): Aux[G, A, I]

Natural transformation.
final def unlift(implicit F: Contravariant[F]): F[A]

Alias for run.
Alias for run.

Annotations
@inline()
final def wait(): Unit

Definition Classes
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Annotations
@throws( ... )
final def wait(arg0: Long, arg1: Int): Unit

Definition Classes
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Annotations
@throws( ... )
final def wait(arg0: Long): Unit

Definition Classes
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Annotations
@throws( ... )

Related Docs: object ContravariantCoyoneda | package scalaz

sealed abstract class ContravariantCoyoneda[F[_], A] extends AnyRef

Type Members

abstract type I

Abstract Value Members

abstract val fi: F[I]

abstract val k: (A) ⇒ I

Concrete Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: Any): Boolean

final def asInstanceOf[T0]: T0

def clone(): AnyRef

final def contramap[B](f: (B) ⇒ A): Aux[F, B, I]

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

def finalize(): Unit

final def getClass(): Class[_]

def hashCode(): Int

final def isInstanceOf[T0]: Boolean

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

final def run(implicit F: Contravariant[F]): F[A]

final def synchronized[T0](arg0: ⇒ T0): T0

def toString(): String

final def trans[G[_]](f: ~>[F, G]): Aux[G, A, I]

final def unlift(implicit F: Contravariant[F]): F[A]

final def wait(): Unit

final def wait(arg0: Long, arg1: Int): Unit

final def wait(arg0: Long): Unit

Inherited from AnyRef

Inherited from Any

Ungrouped