Packages

trait CoflatMap[F[_]] extends Functor[F]

CoflatMap is the dual of FlatMap.

Must obey the laws in cats.laws.CoflatMapLaws

Source
CoflatMap.scala
Linear Supertypes
Functor[F], Invariant[F], Serializable, Serializable, AnyRef, Any
Known Subclasses
Bimonad, Comonad
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Inherited
  1. CoflatMap
  2. Functor
  3. Invariant
  4. Serializable
  5. Serializable
  6. AnyRef
  7. Any
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Visibility
  1. Public
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Abstract Value Members

  1. abstract def coflatMap[A, B](fa: F[A])(f: (F[A]) ⇒ B): F[B]

    coflatMap is the dual of flatMap on FlatMap.

    coflatMap is the dual of flatMap on FlatMap. It applies a value in a context to a function that takes a value in a context and returns a normal value.

    Example:

    scala> import cats.syntax.all._
scala> import cats.CoflatMap
scala> val fa = Some(3)
scala> def f(a: Option[Int]): Int = a match {
     | case Some(x) => 2 * x
     | case None => 0 }
scala> CoflatMap[Option].coflatMap(fa)(f)
res0: Option[Int] = Some(6)
  2. abstract def map[A, B](fa: F[A])(f: (A) ⇒ B): F[B]
    Definition Classes
    Functor

Concrete Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##(): Int
    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  4. def as[A, B](fa: F[A], b: B): F[B]

    Replaces the A value in F[A] with the supplied value.

    Replaces the A value in F[A] with the supplied value.

    Example:

    scala> import cats.syntax.all._

scala> List(1,2,3).as("hello")
res0: List[String] = List(hello, hello, hello)
    Definition Classes
    Functor
  5. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  6. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()
  7. def coflatten[A](fa: F[A]): F[F[A]]

    coflatten is the dual of flatten on FlatMap.

    coflatten is the dual of flatten on FlatMap. Whereas flatten removes a layer of F, coflatten adds a layer of F

    Example:

    scala> import cats.syntax.all._
scala> import cats.CoflatMap
scala> val fa = Some(3)
fa: Option[Int] = Some(3)
scala> CoflatMap[Option].coflatten(fa)
res0: Option[Option[Int]] = Some(Some(3))
  8. def compose[G[_]](implicit arg0: Functor[G]): Functor[[α]F[G[α]]]
    Definition Classes
    Functor
  9. def compose[G[_]](implicit arg0: Invariant[G]): Invariant[[α]F[G[α]]]

    Compose Invariant F[_] and G[_] then produce Invariant[F[G[_]]] using their imap.

    Compose Invariant F[_] and G[_] then produce Invariant[F[G[_]]] using their imap.

    Example:

    scala> import cats.syntax.all._
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
  10. def composeBifunctor[G[_, _]](implicit arg0: Bifunctor[G]): Bifunctor[[α, β]F[G[α, β]]]
    Definition Classes
    Functor
  11. def composeContravariant[G[_]](implicit arg0: Contravariant[G]): Contravariant[[α]F[G[α]]]

    Compose Invariant F[_] and Contravariant G[_] then produce Invariant[F[G[_]]] using F's imap and G's contramap.

    Compose Invariant F[_] and Contravariant G[_] then produce Invariant[F[G[_]]] using F's imap and G's contramap.

    Example:

    scala> import cats.syntax.all._
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
    Functor → Invariant
  12. def composeFunctor[G[_]](implicit arg0: Functor[G]): Invariant[[α]F[G[α]]]

    Compose Invariant F[_] and Functor G[_] then produce Invariant[F[G[_]]] using F's imap and G's map.

    Compose Invariant F[_] and Functor G[_] then produce Invariant[F[G[_]]] using F's imap and G's map.

    Example:

    scala> import cats.syntax.all._
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
    Invariant
  13. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  14. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  15. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  16. final def fmap[A, B](fa: F[A])(f: (A) ⇒ B): F[B]

    Alias for map, since map can't be injected as syntax if the implementing type already had a built-in .map method.

    Alias for map, since map can't be injected as syntax if the implementing type already had a built-in .map method.

    Example:

    scala> import cats.syntax.all._

scala> val m: Map[Int, String] = Map(1 -> "hi", 2 -> "there", 3 -> "you")

scala> m.fmap(_ ++ "!")
res0: Map[Int,String] = Map(1 -> hi!, 2 -> there!, 3 -> you!)
    Definition Classes
    Functor
  17. def fproduct[A, B](fa: F[A])(f: (A) ⇒ B): F[(A, B)]

    Tuple the values in fa with the result of applying a function with the value

    Tuple the values in fa with the result of applying a function with the value

    Example:

    scala> import cats.syntax.all._

scala> Option(42).fproduct(_.toString)
res0: Option[(Int, String)] = Some((42,42))
    Definition Classes
    Functor
  18. def fproductLeft[A, B](fa: F[A])(f: (A) ⇒ B): F[(B, A)]

    Pair the result of function application with A.

    Pair the result of function application with A.

    Example:

    scala> import cats.syntax.all._

scala> Option(42).fproductLeft(_.toString)
res0: Option[(String, Int)] = Some((42,42))
    Definition Classes
    Functor
  19. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  20. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  21. def ifF[A](fb: F[Boolean])(ifTrue: ⇒ A, ifFalse: ⇒ A): F[A]

    Lifts if to Functor

    Lifts if to Functor

    Example:

    scala> import cats.Functor
scala> import cats.implicits.catsStdInstancesForList

scala> Functor[List].ifF(List(true, false, false))(1, 0)
res0: List[Int] = List(1, 0, 0)
    Definition Classes
    Functor
  22. def imap[A, B](fa: F[A])(f: (A) ⇒ B)(g: (B) ⇒ A): F[B]

    Transform an F[A] into an F[B] by providing a transformation from A to B and one from B to A.

    Transform an F[A] into an F[B] by providing a transformation from A to B and one from B to A.

    Example:

    scala> import cats.syntax.all._
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
    Functor → Invariant
  23. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  24. def lift[A, B](f: (A) ⇒ B): (F[A]) ⇒ F[B]

    Lift a function f to operate on Functors

    Lift a function f to operate on Functors

    Example:

    scala> import cats.Functor
scala> import cats.implicits.catsStdInstancesForOption

scala> val o = Option(42)
scala> Functor[Option].lift((x: Int) => x + 10)(o)
res0: Option[Int] = Some(52)
    Definition Classes
    Functor
  25. def mapOrKeep[A, A1 >: A](fa: F[A])(pf: PartialFunction[A, A1]): F[A1]

    Modifies the A value in F[A] with the supplied function, if the function is defined for the value.

    Modifies the A value in F[A] with the supplied function, if the function is defined for the value. Example:

    scala> import cats.syntax.all._

scala> List(1, 2, 3).mapOrKeep { case 2 => 42 }
res0: List[Int] = List(1, 42, 3)
    Definition Classes
    Functor
  26. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  27. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  28. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  29. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  30. def toString(): String
    Definition Classes
    AnyRef → Any
  31. def tupleLeft[A, B](fa: F[A], b: B): F[(B, A)]

    Tuples the A value in F[A] with the supplied B value, with the B value on the left.

    Tuples the A value in F[A] with the supplied B value, with the B value on the left.

    Example:

    scala> import scala.collection.immutable.Queue
scala> import cats.syntax.all._

scala> Queue("hello", "world").tupleLeft(42)
res0: scala.collection.immutable.Queue[(Int, String)] = Queue((42,hello), (42,world))
    Definition Classes
    Functor
  32. def tupleRight[A, B](fa: F[A], b: B): F[(A, B)]

    Tuples the A value in F[A] with the supplied B value, with the B value on the right.

    Tuples the A value in F[A] with the supplied B value, with the B value on the right.

    Example:

    scala> import scala.collection.immutable.Queue
scala> import cats.syntax.all._

scala> Queue("hello", "world").tupleRight(42)
res0: scala.collection.immutable.Queue[(String, Int)] = Queue((hello,42), (world,42))
    Definition Classes
    Functor
  33. def unzip[A, B](fab: F[(A, B)]): (F[A], F[B])

    Un-zips an F[(A, B)] consisting of element pairs or Tuple2 into two separate F's tupled.

    Un-zips an F[(A, B)] consisting of element pairs or Tuple2 into two separate F's tupled.

    NOTE: Check for effect duplication, possibly memoize before

    scala> import cats.Functor
scala> import cats.implicits.catsStdInstancesForList

scala> Functor[List].unzip(List((1,2), (3, 4)))
res0: (List[Int], List[Int]) = (List(1, 3),List(2, 4))
    Definition Classes
    Functor
  34. def void[A](fa: F[A]): F[Unit]

    Empty the fa of the values, preserving the structure

    Empty the fa of the values, preserving the structure

    Example:

    scala> import cats.syntax.all._

scala> List(1,2,3).void
res0: List[Unit] = List((), (), ())
    Definition Classes
    Functor
  35. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  36. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  37. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()
  38. def widen[A, B >: A](fa: F[A]): F[B]

    Lifts natural subtyping covariance of covariant Functors.

    Lifts natural subtyping covariance of covariant Functors.

    NOTE: In certain (perhaps contrived) situations that rely on universal equality this can result in a ClassCastException, because it is implemented as a type cast. It could be implemented as map(identity), but according to the functor laws, that should be equal to fa, and a type cast is often much more performant. See this example of widen creating a ClassCastException.

    Example:

    scala> import cats.syntax.all._

scala> val l = List(Some(42))
scala> l.widen[Option[Int]]
res0: List[Option[Int]] = List(Some(42))
    Definition Classes
    Functor

Inherited from Functor[F]

Inherited from Invariant[F]

Inherited from Serializable

Inherited from Serializable

Inherited from AnyRef

Inherited from Any

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