trait ContravariantMonoidal[F[_]] extends ContravariantSemigroupal[F] with InvariantMonoidal[F]
ContravariantMonoidal functors are functors that supply
a unit along the diagonal map for the contramap2 operation.
Must obey the laws defined in cats.laws.ContravariantMonoidalLaws.
Based on ekmett's contravariant library: https://hackage.haskell.org/package/contravariant-1.4/docs/Data-Functor-Contravariant-Divisible.html
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- @implicitNotFound( ... ) @typeclass( ... , ... )
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- ContravariantMonoidal.scala
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Abstract Value Members
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abstract
def
contramap[A, B](fa: F[A])(f: (B) ⇒ A): F[B]
- Definition Classes
- Contravariant
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abstract
def
product[A, B](fa: F[A], fb: F[B]): F[(A, B)]
Combine an
F[A]and anF[B]into anF[(A, B)]that maintains the effects of bothfaandfb.Combine an
F[A]and anF[B]into anF[(A, B)]that maintains the effects of bothfaandfb.Example:
scala> import cats.implicits._ scala> val noneInt: Option[Int] = None scala> val some3: Option[Int] = Some(3) scala> val noneString: Option[String] = None scala> val someFoo: Option[String] = Some("foo") scala> Semigroupal[Option].product(noneInt, noneString) res0: Option[(Int, String)] = None scala> Semigroupal[Option].product(noneInt, someFoo) res1: Option[(Int, String)] = None scala> Semigroupal[Option].product(some3, noneString) res2: Option[(Int, String)] = None scala> Semigroupal[Option].product(some3, someFoo) res3: Option[(Int, String)] = Some((3,foo))
- Definition Classes
- Semigroupal
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abstract
def
unit: F[Unit]
- Definition Classes
- InvariantMonoidal
Concrete Value Members
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final
def
!=(arg0: Any): Boolean
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final
def
##(): Int
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final
def
==(arg0: Any): Boolean
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final
def
asInstanceOf[T0]: T0
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def
clone(): AnyRef
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def
compose[G[_]](implicit arg0: Contravariant[G]): Functor[[α]F[G[α]]]
- Definition Classes
- Contravariant
-
def
compose[G[_]](implicit arg0: Invariant[G]): Invariant[[α]F[G[α]]]
Compose Invariant
F[_]andG[_]then produceInvariant[F[G[_]]]using theirimap.Compose Invariant
F[_]andG[_]then produceInvariant[F[G[_]]]using theirimap.Example:
scala> import cats.implicits._ scala> import scala.concurrent.duration._ scala> val durSemigroupList: Semigroup[List[FiniteDuration]] = | Invariant[Semigroup].compose[List].imap(Semigroup[List[Long]])(Duration.fromNanos)(_.toNanos) scala> durSemigroupList.combine(List(2.seconds, 3.seconds), List(4.seconds)) res1: List[FiniteDuration] = List(2 seconds, 3 seconds, 4 seconds)
- Definition Classes
- Invariant
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def
composeApply[G[_]](implicit arg0: Apply[G]): InvariantSemigroupal[[α]F[G[α]]]
- Definition Classes
- InvariantSemigroupal
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def
composeContravariant[G[_]](implicit arg0: Contravariant[G]): Invariant[[α]F[G[α]]]
Compose Invariant
F[_]and ContravariantG[_]then produceInvariant[F[G[_]]]using F'simapand G'scontramap.Compose Invariant
F[_]and ContravariantG[_]then produceInvariant[F[G[_]]]using F'simapand G'scontramap.Example:
scala> import cats.implicits._ scala> import scala.concurrent.duration._ scala> type ToInt[T] = T => Int scala> val durSemigroupToInt: Semigroup[ToInt[FiniteDuration]] = | Invariant[Semigroup] | .composeContravariant[ToInt] | .imap(Semigroup[ToInt[Long]])(Duration.fromNanos)(_.toNanos) // semantically equal to (2.seconds.toSeconds.toInt + 1) + (2.seconds.toSeconds.toInt * 2) = 7 scala> durSemigroupToInt.combine(_.toSeconds.toInt + 1, _.toSeconds.toInt * 2)(2.seconds) res1: Int = 7
- Definition Classes
- Invariant
-
def
composeFunctor[G[_]](implicit arg0: Functor[G]): ContravariantSemigroupal[[α]F[G[α]]]
Compose Invariant
F[_]and FunctorG[_]then produceInvariant[F[G[_]]]using F'simapand G'smap.Compose Invariant
F[_]and FunctorG[_]then produceInvariant[F[G[_]]]using F'simapand G'smap.Example:
scala> import cats.implicits._ scala> import scala.concurrent.duration._ scala> val durSemigroupList: Semigroup[List[FiniteDuration]] = | Invariant[Semigroup] | .composeFunctor[List] | .imap(Semigroup[List[Long]])(Duration.fromNanos)(_.toNanos) scala> durSemigroupList.combine(List(2.seconds, 3.seconds), List(4.seconds)) res1: List[FiniteDuration] = List(2 seconds, 3 seconds, 4 seconds)
- Definition Classes
- ContravariantSemigroupal → Contravariant → Invariant
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final
def
eq(arg0: AnyRef): Boolean
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def
equals(arg0: Any): Boolean
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final
def
getClass(): Class[_]
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def
hashCode(): Int
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def
imap[A, B](fa: F[A])(f: (A) ⇒ B)(fi: (B) ⇒ A): F[B]
Transform an
F[A]into anF[B]by providing a transformation fromAtoBand one fromBtoA.Transform an
F[A]into anF[B]by providing a transformation fromAtoBand one fromBtoA.Example:
scala> import cats.implicits._ scala> import scala.concurrent.duration._ scala> val durSemigroup: Semigroup[FiniteDuration] = | Invariant[Semigroup].imap(Semigroup[Long])(Duration.fromNanos)(_.toNanos) scala> durSemigroup.combine(2.seconds, 3.seconds) res1: FiniteDuration = 5 seconds
- Definition Classes
- Contravariant → Invariant
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final
def
isInstanceOf[T0]: Boolean
- Definition Classes
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def
liftContravariant[A, B](f: (A) ⇒ B): (F[B]) ⇒ F[A]
- Definition Classes
- Contravariant
-
def
narrow[A, B <: A](fa: F[A]): F[B]
Lifts natural subtyping contravariance of contravariant Functors.
Lifts natural subtyping contravariance of contravariant Functors. could be implemented as contramap(identity), but the Functor laws say this is equivalent
- Definition Classes
- Contravariant
-
final
def
ne(arg0: AnyRef): Boolean
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final
def
notify(): Unit
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final
def
notifyAll(): Unit
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def
point[A](a: A): F[A]
pointlifts any value into a Monoidal Functor.pointlifts any value into a Monoidal Functor.Example:
scala> import cats.implicits._ scala> InvariantMonoidal[Option].point(10) res0: Option[Int] = Some(10)
- Definition Classes
- InvariantMonoidal
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final
def
synchronized[T0](arg0: ⇒ T0): T0
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-
def
toString(): String
- Definition Classes
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-
def
trivial[A]: F[A]
trivialproduces an instance ofFfor any typeAthat is trivial with respect tocontramap2along the diagonal -
final
def
wait(arg0: Long, arg1: Int): Unit
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final
def
wait(arg0: Long): Unit
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final
def
wait(): Unit
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