Packages

trait TraverseFilter[F[_]] extends FunctorFilter[F]

TraverseFilter, also known as Witherable, represents list-like structures that can essentially have a traverse and a filter applied as a single combined operation (traverseFilter).

Based on Haskell's Data.Witherable

Annotations
@implicitNotFound( ... ) @typeclass( ... , ... )
Source
TraverseFilter.scala
Linear Supertypes
FunctorFilter[F], Serializable, Serializable, AnyRef, Any
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Inherited
  1. TraverseFilter
  2. FunctorFilter
  3. Serializable
  4. Serializable
  5. AnyRef
  6. Any
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Visibility
  1. Public
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Abstract Value Members

  1. abstract def traverse: Traverse[F]
  2. abstract def traverseFilter[G[_], A, B](fa: F[A])(f: (A) ⇒ G[Option[B]])(implicit G: Applicative[G]): G[F[B]]

    A combined traverse and filter.

    A combined traverse and filter. Filtering is handled via Option instead of Boolean such that the output type B can be different than the input type A.

    Example:

    scala> import cats.implicits._
    scala> val m: Map[Int, String] = Map(1 -> "one", 3 -> "three")
    scala> val l: List[Int] = List(1, 2, 3, 4)
    scala> def asString(i: Int): Eval[Option[String]] = Now(m.get(i))
    scala> val result: Eval[List[String]] = l.traverseFilter(asString)
    scala> result.value
    res0: List[String] = List(one, three)

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. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  5. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()
  6. def collect[A, B](fa: F[A])(f: PartialFunction[A, B]): F[B]

    Similar to mapFilter but uses a partial function instead of a function that returns an Option.

    Similar to mapFilter but uses a partial function instead of a function that returns an Option.

    Example:

    scala> import cats.implicits._
    scala> val l: List[Int] = List(1, 2, 3, 4)
    scala> FunctorFilter[List].collect(l){
         |   case 1 => "one"
         |   case 3 => "three"
         | }
    res0: List[String] = List(one, three)
    Definition Classes
    FunctorFilter
  7. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  8. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  9. def filter[A](fa: F[A])(f: (A) ⇒ Boolean): F[A]

    Apply a filter to a structure such that the output structure contains all A elements in the input structure that satisfy the predicate f but none that don't.

    Apply a filter to a structure such that the output structure contains all A elements in the input structure that satisfy the predicate f but none that don't.

    Definition Classes
    FunctorFilter
  10. def filterA[G[_], A](fa: F[A])(f: (A) ⇒ G[Boolean])(implicit G: Applicative[G]): G[F[A]]

    Filter values inside a G context.

    Filter values inside a G context.

    This is a generalized version of Haskell's filterM. This StackOverflow question about filterM may be helpful in understanding how it behaves.

    Example:

    scala> import cats.implicits._
    scala> val l: List[Int] = List(1, 2, 3, 4)
    scala> def odd(i: Int): Eval[Boolean] = Now(i % 2 == 1)
    scala> val res: Eval[List[Int]] = l.filterA(odd)
    scala> res.value
    res0: List[Int] = List(1, 3)
    
    scala> List(1, 2, 3).filterA(_ => List(true, false))
    res1: List[List[Int]] = List(List(1, 2, 3), List(1, 2), List(1, 3), List(1), List(2, 3), List(2), List(3), List())
  11. def filterNot[A](fa: F[A])(f: (A) ⇒ Boolean): F[A]

    Apply a filter to a structure such that the output structure contains all A elements in the input structure that do not satisfy the predicate f.

    Apply a filter to a structure such that the output structure contains all A elements in the input structure that do not satisfy the predicate f.

    Definition Classes
    FunctorFilter
  12. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  13. def flattenOption[A](fa: F[Option[A]]): F[A]

    "Flatten" out a structure by collapsing Options.

    "Flatten" out a structure by collapsing Options. Equivalent to using mapFilter with identity.

    Example:

    scala> import cats.implicits._
    scala> val l: List[Option[Int]] = List(Some(1), None, Some(3), None)
    scala> l.flattenOption
    res0: List[Int] = List(1, 3)
    Definition Classes
    FunctorFilter
  14. final def functor: Functor[F]
    Definition Classes
    TraverseFilterFunctorFilter
  15. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  16. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  17. def hashDistinct[A](fa: F[A])(implicit H: Hash[A]): F[A]

    Removes duplicate elements from a list, keeping only the first occurrence.

    Removes duplicate elements from a list, keeping only the first occurrence. This is usually faster than ordDistinct, especially for things that have a slow comparion (like String).

  18. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  19. def mapFilter[A, B](fa: F[A])(f: (A) ⇒ Option[B]): F[B]

    A combined map and filter.

    A combined map and filter. Filtering is handled via Option instead of Boolean such that the output type B can be different than the input type A.

    Example:

    scala> import cats.implicits._
    scala> val m: Map[Int, String] = Map(1 -> "one", 3 -> "three")
    scala> val l: List[Int] = List(1, 2, 3, 4)
    scala> def asString(i: Int): Option[String] = m.get(i)
    scala> l.mapFilter(asString)
    res0: List[String] = List(one, three)
    Definition Classes
    TraverseFilterFunctorFilter
  20. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  21. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  22. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  23. def ordDistinct[A](fa: F[A])(implicit O: Order[A]): F[A]

    Removes duplicate elements from a list, keeping only the first occurrence.

  24. def sequenceFilter[G[_], A](fgoa: F[G[Option[A]]])(implicit G: Applicative[G]): G[F[A]]

    scala> import cats.implicits._
    scala> val a: List[Either[String, Option[Int]]] = List(Right(Some(1)), Right(Some(5)), Right(Some(3)))
    scala> val b: Either[String, List[Int]] = TraverseFilter[List].sequenceFilter(a)
    b: Either[String, List[Int]] = Right(List(1, 5, 3))
    Annotations
    @noop()
  25. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  26. def toString(): String
    Definition Classes
    AnyRef → Any
  27. def traverseEither[G[_], A, B, E](fa: F[A])(f: (A) ⇒ G[Either[E, B]])(g: (A, E) ⇒ G[Unit])(implicit G: Monad[G]): G[F[B]]

    Like traverseFilter, but uses Either instead of Option and allows for an action to be run on each filtered value.

  28. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  29. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  30. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()

Inherited from FunctorFilter[F]

Inherited from Serializable

Inherited from Serializable

Inherited from AnyRef

Inherited from Any

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