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

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

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Type Members

  1. abstract type I

    The pivot between fi and k, usually existential.

Abstract Value Members

  1. abstract val fi: F[I]

    The underlying value.

  2. abstract val k: (A) ⇒ I

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

Concrete Value Members

  1. final def !=(arg0: Any): Boolean
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  2. final def ##(): Int
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  3. final def ==(arg0: Any): Boolean
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  4. final def asInstanceOf[T0]: T0
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  5. def clone(): AnyRef
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    protected[java.lang]
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    @native() @throws( ... )
  6. 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.

  7. final def eq(arg0: AnyRef): Boolean
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  8. def equals(arg0: Any): Boolean
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  9. def finalize(): Unit
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    @throws( classOf[java.lang.Throwable] )
  10. final def getClass(): Class[_]
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  11. def hashCode(): Int
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    @native()
  12. final def isInstanceOf[T0]: Boolean
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  13. final def ne(arg0: AnyRef): Boolean
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  14. final def notify(): Unit
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  15. final def notifyAll(): Unit
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    @native()
  16. final def run(implicit F: Contravariant[F]): F[A]

    Converts to F[A] given that F is a contravariant.

  17. final def synchronized[T0](arg0: ⇒ T0): T0
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  18. def toString(): String
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  19. final def trans[G[_]](f: ~>[F, G]): Aux[G, A, I]

    Natural transformation.

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

    Alias for run.

    Alias for run.

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  21. final def wait(): Unit
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  22. final def wait(arg0: Long, arg1: Int): Unit
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  23. final def wait(arg0: Long): Unit
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