trait NonEmptyTraverse[F[_]] extends Traverse[F] with Reducible[F] with Serializable

NonEmptyTraverse, also known as Traversable1.

NonEmptyTraverse is like a non-empty Traverse. In addition to the traverse and sequence methods it provides nonEmptyTraverse and nonEmptySequence methods which require an Apply instance instead of Applicative.

Self Type
NonEmptyTraverse[F]
Source
NonEmptyTraverse.scala
Linear Supertypes
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Inherited
  1. NonEmptyTraverse
  2. Reducible
  3. Traverse
  4. UnorderedTraverse
  5. Foldable
  6. UnorderedFoldable
  7. Functor
  8. Invariant
  9. Serializable
  10. Serializable
  11. AnyRef
  12. Any
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Visibility
  1. Public
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Abstract Value Members

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

    Left associative fold on 'F' using the function 'f'.

    Left associative fold on 'F' using the function 'f'.

    Example:

    scala> import cats.Foldable, cats.implicits._
    scala> val fa = Option(1)
    
    Folding by addition to zero:
    scala> Foldable[Option].foldLeft(fa, Option(0))((a, n) => a.map(_ + n))
    res0: Option[Int] = Some(1)

    With syntax extensions, foldLeft can be used like:

    Folding `Option` with addition from zero:
    scala> fa.foldLeft(Option(0))((a, n) => a.map(_ + n))
    res1: Option[Int] = Some(1)
    
    There's also an alias `foldl` which is equivalent:
    scala> fa.foldl(Option(0))((a, n) => a.map(_ + n))
    res2: Option[Int] = Some(1)
    Definition Classes
    Foldable
  2. abstract def foldRight[A, B](fa: F[A], lb: Eval[B])(f: (A, Eval[B]) ⇒ Eval[B]): Eval[B]

    Right associative lazy fold on F using the folding function 'f'.

    Right associative lazy fold on F using the folding function 'f'.

    This method evaluates lb lazily (in some cases it will not be needed), and returns a lazy value. We are using (A, Eval[B]) => Eval[B] to support laziness in a stack-safe way. Chained computation should be performed via .map and .flatMap.

    For more detailed information about how this method works see the documentation for Eval[_].

    Example:

    scala> import cats.Foldable, cats.Eval, cats.implicits._
    scala> val fa = Option(1)
    
    Folding by addition to zero:
    scala> val folded1 = Foldable[Option].foldRight(fa, Eval.now(0))((n, a) => a.map(_ + n))
    Since `foldRight` yields a lazy computation, we need to force it to inspect the result:
    scala> folded1.value
    res0: Int = 1
    
    With syntax extensions, we can write the same thing like this:
    scala> val folded2 = fa.foldRight(Eval.now(0))((n, a) => a.map(_ + n))
    scala> folded2.value
    res1: Int = 1
    
    Unfortunately, since `foldRight` is defined on many collections - this
    extension clashes with the operation defined in `Foldable`.
    
    To get past this and make sure you're getting the lazy `foldRight` defined
    in `Foldable`, there's an alias `foldr`:
    scala> val folded3 = fa.foldr(Eval.now(0))((n, a) => a.map(_ + n))
    scala> folded3.value
    res1: Int = 1
    Definition Classes
    Foldable
  3. abstract def nonEmptyTraverse[G[_], A, B](fa: F[A])(f: (A) ⇒ G[B])(implicit arg0: Apply[G]): G[F[B]]

    Given a function which returns a G effect, thread this effect through the running of this function on all the values in F, returning an F[B] in a G context.

    Given a function which returns a G effect, thread this effect through the running of this function on all the values in F, returning an F[B] in a G context.

    Example:

    scala> import cats.implicits._
    scala> import cats.data.NonEmptyList
    scala> def countWords(words: List[String]): Map[String, Int] = words.groupBy(identity).map { case (k, v) => (k, v.length) }
    scala> NonEmptyList.of(List("How", "do", "you", "fly"), List("What", "do", "you", "do")).nonEmptyTraverse(countWords)
    res0: Map[String,cats.data.NonEmptyList[Int]] = Map(do -> NonEmptyList(1, 2), you -> NonEmptyList(1, 1))
  4. abstract def reduceLeftTo[A, B](fa: F[A])(f: (A) ⇒ B)(g: (B, A) ⇒ B): B

    Apply f to the "initial element" of fa and combine it with every other value using the given function g.

    Apply f to the "initial element" of fa and combine it with every other value using the given function g.

    Definition Classes
    Reducible
  5. abstract def reduceRightTo[A, B](fa: F[A])(f: (A) ⇒ B)(g: (A, Eval[B]) ⇒ Eval[B]): Eval[B]

    Apply f to the "initial element" of fa and lazily combine it with every other value using the given function g.

    Apply f to the "initial element" of fa and lazily combine it with every other value using the given function g.

    Definition Classes
    Reducible

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.Functor
    scala> import cats.implicits.catsStdInstancesForList
    
    scala> Functor[List].as(List(1,2,3), "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[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @native() @throws( ... )
  7. def collectFirst[A, B](fa: F[A])(pf: PartialFunction[A, B]): Option[B]
    Definition Classes
    Foldable
  8. def collectFirstSome[A, B](fa: F[A])(f: (A) ⇒ Option[B]): Option[B]

    Like collectFirst from scala.collection.Traversable but takes A => Option[B] instead of PartialFunctions.

    Like collectFirst from scala.collection.Traversable but takes A => Option[B] instead of PartialFunctions.

    scala> import cats.implicits._
    scala> val keys = List(1, 2, 4, 5)
    scala> val map = Map(4 -> "Four", 5 -> "Five")
    scala> keys.collectFirstSome(map.get)
    res0: Option[String] = Some(Four)
    scala> val map2 = Map(6 -> "Six", 7 -> "Seven")
    scala> keys.collectFirstSome(map2.get)
    res1: Option[String] = None
    Definition Classes
    Foldable
  9. def combineAll[A](fa: F[A])(implicit arg0: Monoid[A]): A

    Alias for fold.

    Alias for fold.

    Definition Classes
    Foldable
  10. def compose[G[_]](implicit arg0: NonEmptyTraverse[G]): NonEmptyTraverse[[α]F[G[α]]]
  11. def compose[G[_]](implicit arg0: Reducible[G]): Reducible[[α]F[G[α]]]
    Definition Classes
    Reducible
  12. def compose[G[_]](implicit arg0: Traverse[G]): Traverse[[α]F[G[α]]]
    Definition Classes
    Traverse
  13. def compose[G[_]](implicit arg0: Foldable[G]): Foldable[[α]F[G[α]]]
    Definition Classes
    Foldable
  14. def compose[G[_]](implicit arg0: Functor[G]): Functor[[α]F[G[α]]]
    Definition Classes
    Functor
  15. def compose[G[_]](implicit arg0: Invariant[G]): Invariant[[α]F[G[α]]]
    Definition Classes
    Invariant
  16. def composeContravariant[G[_]](implicit arg0: Contravariant[G]): Contravariant[[α]F[G[α]]]
    Definition Classes
    FunctorInvariant
  17. def composeFunctor[G[_]](implicit arg0: Functor[G]): Invariant[[α]F[G[α]]]
    Definition Classes
    Invariant
  18. def dropWhile_[A](fa: F[A])(p: (A) ⇒ Boolean): List[A]

    Convert F[A] to a List[A], dropping all initial elements which match p.

    Convert F[A] to a List[A], dropping all initial elements which match p.

    Definition Classes
    Foldable
  19. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  20. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  21. def exists[A](fa: F[A])(p: (A) ⇒ Boolean): Boolean

    Check whether at least one element satisfies the predicate.

    Check whether at least one element satisfies the predicate.

    If there are no elements, the result is false.

    Definition Classes
    FoldableUnorderedFoldable
  22. def existsM[G[_], A](fa: F[A])(p: (A) ⇒ G[Boolean])(implicit G: Monad[G]): G[Boolean]

    Check whether at least one element satisfies the effectful predicate.

    Check whether at least one element satisfies the effectful predicate.

    If there are no elements, the result is false. existsM short-circuits, i.e. once a true result is encountered, no further effects are produced.

    For example:

    scala> import cats.implicits._
    scala> val F = Foldable[List]
    scala> F.existsM(List(1,2,3,4))(n => Option(n <= 4))
    res0: Option[Boolean] = Some(true)
    
    scala> F.existsM(List(1,2,3,4))(n => Option(n > 4))
    res1: Option[Boolean] = Some(false)
    
    scala> F.existsM(List(1,2,3,4))(n => if (n <= 2) Option(true) else Option(false))
    res2: Option[Boolean] = Some(true)
    
    scala> F.existsM(List(1,2,3,4))(n => if (n <= 2) Option(true) else None)
    res3: Option[Boolean] = Some(true)
    
    scala> F.existsM(List(1,2,3,4))(n => if (n <= 2) None else Option(true))
    res4: Option[Boolean] = None
    Definition Classes
    Foldable
  23. def filter_[A](fa: F[A])(p: (A) ⇒ Boolean): List[A]

    Convert F[A] to a List[A], only including elements which match p.

    Convert F[A] to a List[A], only including elements which match p.

    Definition Classes
    Foldable
  24. def finalize(): Unit
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  25. def find[A](fa: F[A])(f: (A) ⇒ Boolean): Option[A]

    Find the first element matching the predicate, if one exists.

    Find the first element matching the predicate, if one exists.

    Definition Classes
    Foldable
  26. def flatSequence[G[_], A](fgfa: F[G[F[A]]])(implicit G: Applicative[G], F: FlatMap[F]): G[F[A]]

    Thread all the G effects through the F structure and flatten to invert the structure from F[G[F[A]]] to G[F[A]].

    Thread all the G effects through the F structure and flatten to invert the structure from F[G[F[A]]] to G[F[A]].

    Example:

    scala> import cats.implicits._
    scala> val x: List[Option[List[Int]]] = List(Some(List(1, 2)), Some(List(3)))
    scala> val y: List[Option[List[Int]]] = List(None, Some(List(3)))
    scala> x.flatSequence
    res0: Option[List[Int]] = Some(List(1, 2, 3))
    scala> y.flatSequence
    res1: Option[List[Int]] = None
    Definition Classes
    Traverse
  27. def flatTraverse[G[_], A, B](fa: F[A])(f: (A) ⇒ G[F[B]])(implicit G: Applicative[G], F: FlatMap[F]): G[F[B]]

    A traverse followed by flattening the inner result.

    A traverse followed by flattening the inner result.

    Example:

    scala> import cats.implicits._
    scala> def parseInt(s: String): Option[Int] = Either.catchOnly[NumberFormatException](s.toInt).toOption
    scala> val x = Option(List("1", "two", "3"))
    scala> x.flatTraverse(_.map(parseInt))
    res0: List[Option[Int]] = List(Some(1), None, Some(3))
    Definition Classes
    Traverse
  28. 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.implicits._
    
    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
  29. def fold[A](fa: F[A])(implicit A: Monoid[A]): A

    Fold implemented using the given Monoid[A] instance.

    Fold implemented using the given Monoid[A] instance.

    Definition Classes
    Foldable
  30. def foldK[G[_], A](fga: F[G[A]])(implicit G: MonoidK[G]): G[A]

    Fold implemented using the given MonoidK[G] instance.

    Fold implemented using the given MonoidK[G] instance.

    This method is identical to fold, except that we use the universal monoid (MonoidK[G]) to get a Monoid[G[A]] instance.

    For example:

    scala> import cats.implicits._
    scala> val F = Foldable[List]
    scala> F.foldK(List(1 :: 2 :: Nil, 3 :: 4 :: 5 :: Nil))
    res0: List[Int] = List(1, 2, 3, 4, 5)
    Definition Classes
    Foldable
  31. final def foldLeftM[G[_], A, B](fa: F[A], z: B)(f: (B, A) ⇒ G[B])(implicit G: Monad[G]): G[B]

    Alias for foldM.

    Alias for foldM.

    Definition Classes
    Foldable
  32. def foldM[G[_], A, B](fa: F[A], z: B)(f: (B, A) ⇒ G[B])(implicit G: Monad[G]): G[B]

    Perform a stack-safe monadic left fold from the source context F into the target monad G.

    Perform a stack-safe monadic left fold from the source context F into the target monad G.

    This method can express short-circuiting semantics. Even when fa is an infinite structure, this method can potentially terminate if the foldRight implementation for F and the tailRecM implementation for G are sufficiently lazy.

    Instances for concrete structures (e.g. List) will often have a more efficient implementation than the default one in terms of foldRight.

    Definition Classes
    Foldable
  33. def foldMap[A, B](fa: F[A])(f: (A) ⇒ B)(implicit B: Monoid[B]): B

    Fold implemented by mapping A values into B and then combining them using the given Monoid[B] instance.

    Fold implemented by mapping A values into B and then combining them using the given Monoid[B] instance.

    Definition Classes
    Foldable
  34. def foldMapM[G[_], A, B](fa: F[A])(f: (A) ⇒ G[B])(implicit G: Monad[G], B: Monoid[B]): G[B]

    Monadic folding on F by mapping A values to G[B], combining the B values using the given Monoid[B] instance.

    Monadic folding on F by mapping A values to G[B], combining the B values using the given Monoid[B] instance.

    Similar to foldM, but using a Monoid[B].

    scala> import cats.Foldable
    scala> import cats.implicits._
    scala> val evenNumbers = List(2,4,6,8,10)
    scala> val evenOpt: Int => Option[Int] =
         |   i => if (i % 2 == 0) Some(i) else None
    scala> Foldable[List].foldMapM(evenNumbers)(evenOpt)
    res0: Option[Int] = Some(30)
    scala> Foldable[List].foldMapM(evenNumbers :+ 11)(evenOpt)
    res1: Option[Int] = None
    Definition Classes
    Foldable
  35. def forall[A](fa: F[A])(p: (A) ⇒ Boolean): Boolean

    Check whether all elements satisfy the predicate.

    Check whether all elements satisfy the predicate.

    If there are no elements, the result is true.

    Definition Classes
    FoldableUnorderedFoldable
  36. def forallM[G[_], A](fa: F[A])(p: (A) ⇒ G[Boolean])(implicit G: Monad[G]): G[Boolean]

    Check whether all elements satisfy the effectful predicate.

    Check whether all elements satisfy the effectful predicate.

    If there are no elements, the result is true. forallM short-circuits, i.e. once a false result is encountered, no further effects are produced.

    For example:

    scala> import cats.implicits._
    scala> val F = Foldable[List]
    scala> F.forallM(List(1,2,3,4))(n => Option(n <= 4))
    res0: Option[Boolean] = Some(true)
    
    scala> F.forallM(List(1,2,3,4))(n => Option(n <= 1))
    res1: Option[Boolean] = Some(false)
    
    scala> F.forallM(List(1,2,3,4))(n => if (n <= 2) Option(true) else Option(false))
    res2: Option[Boolean] = Some(false)
    
    scala> F.forallM(List(1,2,3,4))(n => if (n <= 2) Option(false) else None)
    res3: Option[Boolean] = Some(false)
    
    scala> F.forallM(List(1,2,3,4))(n => if (n <= 2) None else Option(false))
    res4: Option[Boolean] = None
    Definition Classes
    Foldable
  37. 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.Functor
    scala> import cats.implicits.catsStdInstancesForOption
    
    scala> Functor[Option].fproduct(Option(42))(_.toString)
    res0: Option[(Int, String)] = Some((42,42))
    Definition Classes
    Functor
  38. def get[A](fa: F[A])(idx: Long): Option[A]

    Get the element at the index of the Foldable.

    Get the element at the index of the Foldable.

    Definition Classes
    Foldable
  39. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  40. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  41. 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.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
    FunctorInvariant
  42. def intercalate[A](fa: F[A], a: A)(implicit A: Monoid[A]): A

    Intercalate/insert an element between the existing elements while folding.

    Intercalate/insert an element between the existing elements while folding.

    scala> import cats.implicits._
    scala> Foldable[List].intercalate(List("a","b","c"), "-")
    res0: String = a-b-c
    scala> Foldable[List].intercalate(List("a"), "-")
    res1: String = a
    scala> Foldable[List].intercalate(List.empty[String], "-")
    res2: String = ""
    scala> Foldable[Vector].intercalate(Vector(1,2,3), 1)
    res3: Int = 8
    Definition Classes
    Foldable
  43. def intersperseList[A](xs: List[A], x: A): List[A]
    Attributes
    protected
    Definition Classes
    Foldable
  44. def isEmpty[A](fa: F[A]): Boolean

    Returns true if there are no elements.

    Returns true if there are no elements. Otherwise false.

    Definition Classes
    ReducibleFoldableUnorderedFoldable
  45. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  46. 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
  47. def map[A, B](fa: F[A])(f: (A) ⇒ B): F[B]
    Definition Classes
    TraverseFunctor
  48. def mapWithIndex[A, B](fa: F[A])(f: (A, Int) ⇒ B): F[B]

    Akin to map, but also provides the value's index in structure F when calling the function.

    Akin to map, but also provides the value's index in structure F when calling the function.

    Definition Classes
    Traverse
  49. def maximum[A](fa: F[A])(implicit A: Order[A]): A
    Definition Classes
    Reducible
  50. def maximumOption[A](fa: F[A])(implicit A: Order[A]): Option[A]

    Find the maximum A item in this structure according to the Order[A].

    Find the maximum A item in this structure according to the Order[A].

    returns

    None if the structure is empty, otherwise the maximum element wrapped in a Some.

    Definition Classes
    ReducibleFoldable
    See also

    Reducible#maximum for a version that doesn't need to return an Option for structures that are guaranteed to be non-empty.

    minimumOption for minimum instead of maximum.

  51. def minimum[A](fa: F[A])(implicit A: Order[A]): A
    Definition Classes
    Reducible
  52. def minimumOption[A](fa: F[A])(implicit A: Order[A]): Option[A]

    Find the minimum A item in this structure according to the Order[A].

    Find the minimum A item in this structure according to the Order[A].

    returns

    None if the structure is empty, otherwise the minimum element wrapped in a Some.

    Definition Classes
    ReducibleFoldable
    See also

    Reducible#minimum for a version that doesn't need to return an Option for structures that are guaranteed to be non-empty.

    maximumOption for maximum instead of minimum.

  53. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  54. def nonEmpty[A](fa: F[A]): Boolean
    Definition Classes
    ReducibleFoldableUnorderedFoldable
  55. def nonEmptyFlatSequence[G[_], A](fgfa: F[G[F[A]]])(implicit G: Apply[G], F: FlatMap[F]): G[F[A]]

    Thread all the G effects through the F structure and flatten to invert the structure from F[G[F[A]]] to G[F[A]].

    Thread all the G effects through the F structure and flatten to invert the structure from F[G[F[A]]] to G[F[A]].

    Example:

    scala> import cats.implicits._
    scala> import cats.data.NonEmptyList
    scala> val x = NonEmptyList.of(Map(0 ->NonEmptyList.of(1, 2)), Map(0 -> NonEmptyList.of(3)))
    scala> val y: NonEmptyList[Map[Int, NonEmptyList[Int]]] = NonEmptyList.of(Map(), Map(1 -> NonEmptyList.of(3)))
    scala> x.nonEmptyFlatSequence
    res0: Map[Int,cats.data.NonEmptyList[Int]] = Map(0 -> NonEmptyList(1, 2, 3))
    scala> y.nonEmptyFlatSequence
    res1: Map[Int,cats.data.NonEmptyList[Int]] = Map()
  56. def nonEmptyFlatTraverse[G[_], A, B](fa: F[A])(f: (A) ⇒ G[F[B]])(implicit G: Apply[G], F: FlatMap[F]): G[F[B]]

    A nonEmptyTraverse followed by flattening the inner result.

    A nonEmptyTraverse followed by flattening the inner result.

    Example:

    scala> import cats.implicits._
    scala> import cats.data.NonEmptyList
    scala> val x = NonEmptyList.of(List("How", "do", "you", "fly"), List("What", "do", "you", "do"))
    scala> x.nonEmptyFlatTraverse(_.groupByNel(identity) : Map[String, NonEmptyList[String]])
    res0: Map[String,cats.data.NonEmptyList[String]] = Map(do -> NonEmptyList(do, do, do), you -> NonEmptyList(you, you))
  57. def nonEmptyIntercalate[A](fa: F[A], a: A)(implicit A: Semigroup[A]): A

    Intercalate/insert an element between the existing elements while reducing.

    Intercalate/insert an element between the existing elements while reducing.

    scala> import cats.implicits._
    scala> import cats.data.NonEmptyList
    scala> val nel = NonEmptyList.of("a", "b", "c")
    scala> Reducible[NonEmptyList].nonEmptyIntercalate(nel, "-")
    res0: String = a-b-c
    scala> Reducible[NonEmptyList].nonEmptyIntercalate(NonEmptyList.of("a"), "-")
    res1: String = a
    Definition Classes
    Reducible
  58. def nonEmptyPartition[A, B, C](fa: F[A])(f: (A) ⇒ Either[B, C]): Ior[NonEmptyList[B], NonEmptyList[C]]

    Partition this Reducible by a separating function A => Either[B, C]

    Partition this Reducible by a separating function A => Either[B, C]

    scala> import cats.data.NonEmptyList
    scala> val nel = NonEmptyList.of(1,2,3,4)
    scala> Reducible[NonEmptyList].nonEmptyPartition(nel)(a => if (a % 2 == 0) Left(a.toString) else Right(a))
    res0: cats.data.Ior[cats.data.NonEmptyList[String],cats.data.NonEmptyList[Int]] = Both(NonEmptyList(2, 4),NonEmptyList(1, 3))
    scala> Reducible[NonEmptyList].nonEmptyPartition(nel)(a => Right(a * 4))
    res1: cats.data.Ior[cats.data.NonEmptyList[Nothing],cats.data.NonEmptyList[Int]] = Right(NonEmptyList(4, 8, 12, 16))
    Definition Classes
    Reducible
  59. def nonEmptySequence[G[_], A](fga: F[G[A]])(implicit arg0: Apply[G]): G[F[A]]

    Thread all the G effects through the F structure to invert the structure from F[G[A]] to G[F[A]].

    Thread all the G effects through the F structure to invert the structure from F[G[A]] to G[F[A]].

    Example:

    scala> import cats.implicits._
    scala> import cats.data.NonEmptyList
    scala> val x = NonEmptyList.of(Map("do" -> 1, "you" -> 1), Map("do" -> 2, "you" -> 1))
    scala> val y = NonEmptyList.of(Map("How" -> 3, "do" -> 1, "you" -> 1), Map[String,Int]())
    scala> x.nonEmptySequence
    res0: Map[String,NonEmptyList[Int]] = Map(do -> NonEmptyList(1, 2), you -> NonEmptyList(1, 1))
    scala> y.nonEmptySequence
    res1: Map[String,NonEmptyList[Int]] = Map()
  60. def nonEmptySequence_[G[_], A](fga: F[G[A]])(implicit G: Apply[G]): G[Unit]

    Sequence F[G[A]] using Apply[G].

    Sequence F[G[A]] using Apply[G].

    This method is similar to Foldable.sequence_ but requires only an Apply instance for G instead of Applicative. See the nonEmptyTraverse_ documentation for a description of the differences.

    Definition Classes
    Reducible
  61. def nonEmptyTraverse_[G[_], A, B](fa: F[A])(f: (A) ⇒ G[B])(implicit G: Apply[G]): G[Unit]

    Traverse F[A] using Apply[G].

    Traverse F[A] using Apply[G].

    A values will be mapped into G[B] and combined using Apply#map2.

    This method is similar to Foldable.traverse_. There are two main differences:

    1. We only need an Apply instance for G here, since we don't need to call Applicative.pure for a starting value. 2. This performs a strict left-associative traversal and thus must always traverse the entire data structure. Prefer Foldable.traverse_ if you have an Applicative instance available for G and want to take advantage of short-circuiting the traversal.

    Definition Classes
    Reducible
  62. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  63. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  64. def partitionEither[A, B, C](fa: F[A])(f: (A) ⇒ Either[B, C])(implicit A: Alternative[F]): (F[B], F[C])

    Separate this Foldable into a Tuple by a separating function A => Either[B, C] Equivalent to Functor#map and then Alternative#separate.

    Separate this Foldable into a Tuple by a separating function A => Either[B, C] Equivalent to Functor#map and then Alternative#separate.

    scala> import cats.implicits._
    scala> val list = List(1,2,3,4)
    scala> Foldable[List].partitionEither(list)(a => if (a % 2 == 0) Left(a.toString) else Right(a))
    res0: (List[String], List[Int]) = (List(2, 4),List(1, 3))
    scala> Foldable[List].partitionEither(list)(a => Right(a * 4))
    res1: (List[Nothing], List[Int]) = (List(),List(4, 8, 12, 16))
    Definition Classes
    Foldable
  65. def reduce[A](fa: F[A])(implicit A: Semigroup[A]): A

    Reduce a F[A] value using the given Semigroup[A].

    Reduce a F[A] value using the given Semigroup[A].

    Definition Classes
    Reducible
  66. def reduceK[G[_], A](fga: F[G[A]])(implicit G: SemigroupK[G]): G[A]

    Reduce a F[G[A]] value using SemigroupK[G], a universal semigroup for G[_].

    Reduce a F[G[A]] value using SemigroupK[G], a universal semigroup for G[_].

    This method is a generalization of reduce.

    Definition Classes
    Reducible
  67. def reduceLeft[A](fa: F[A])(f: (A, A) ⇒ A): A

    Left-associative reduction on F using the function f.

    Left-associative reduction on F using the function f.

    Implementations should override this method when possible.

    Definition Classes
    Reducible
  68. def reduceLeftM[G[_], A, B](fa: F[A])(f: (A) ⇒ G[B])(g: (B, A) ⇒ G[B])(implicit G: FlatMap[G]): G[B]

    Monadic variant of reduceLeftTo

    Monadic variant of reduceLeftTo

    Definition Classes
    Reducible
  69. def reduceLeftOption[A](fa: F[A])(f: (A, A) ⇒ A): Option[A]

    Reduce the elements of this structure down to a single value by applying the provided aggregation function in a left-associative manner.

    Reduce the elements of this structure down to a single value by applying the provided aggregation function in a left-associative manner.

    returns

    None if the structure is empty, otherwise the result of combining the cumulative left-associative result of the f operation over all of the elements.

    Definition Classes
    Foldable
    See also

    reduceRightOption for a right-associative alternative.

    Reducible#reduceLeft for a version that doesn't need to return an Option for structures that are guaranteed to be non-empty. Example:

    scala> import cats.implicits._
    scala> val l = List(6, 3, 2)
    This is equivalent to (6 - 3) - 2
    scala> Foldable[List].reduceLeftOption(l)(_ - _)
    res0: Option[Int] = Some(1)
    
    scala> Foldable[List].reduceLeftOption(List.empty[Int])(_ - _)
    res1: Option[Int] = None
  70. def reduceLeftToOption[A, B](fa: F[A])(f: (A) ⇒ B)(g: (B, A) ⇒ B): Option[B]

    Overridden from Foldable for efficiency.

    Overridden from Foldable for efficiency.

    Definition Classes
    ReducibleFoldable
  71. def reduceMap[A, B](fa: F[A])(f: (A) ⇒ B)(implicit B: Semigroup[B]): B

    Apply f to each element of fa and combine them using the given Semigroup[B].

    Apply f to each element of fa and combine them using the given Semigroup[B].

    Definition Classes
    Reducible
  72. def reduceMapM[G[_], A, B](fa: F[A])(f: (A) ⇒ G[B])(implicit G: FlatMap[G], B: Semigroup[B]): G[B]

    Monadic reducing by mapping the A values to G[B].

    Monadic reducing by mapping the A values to G[B]. combining the B values using the given Semigroup[B] instance.

    Similar to reduceLeftM, but using a Semigroup[B].

    scala> import cats.Reducible
    scala> import cats.data.NonEmptyList
    scala> import cats.implicits._
    scala> val evenOpt: Int => Option[Int] =
         |   i => if (i % 2 == 0) Some(i) else None
    scala> val allEven = NonEmptyList.of(2,4,6,8,10)
    allEven: cats.data.NonEmptyList[Int] = NonEmptyList(2, 4, 6, 8, 10)
    scala> val notAllEven = allEven ++ List(11)
    notAllEven: cats.data.NonEmptyList[Int] = NonEmptyList(2, 4, 6, 8, 10, 11)
    scala> Reducible[NonEmptyList].reduceMapM(allEven)(evenOpt)
    res0: Option[Int] = Some(30)
    scala> Reducible[NonEmptyList].reduceMapM(notAllEven)(evenOpt)
    res1: Option[Int] = None
    Definition Classes
    Reducible
  73. def reduceRight[A](fa: F[A])(f: (A, Eval[A]) ⇒ Eval[A]): Eval[A]

    Right-associative reduction on F using the function f.

    Right-associative reduction on F using the function f.

    Definition Classes
    Reducible
  74. def reduceRightOption[A](fa: F[A])(f: (A, Eval[A]) ⇒ Eval[A]): Eval[Option[A]]

    Reduce the elements of this structure down to a single value by applying the provided aggregation function in a right-associative manner.

    Reduce the elements of this structure down to a single value by applying the provided aggregation function in a right-associative manner.

    returns

    None if the structure is empty, otherwise the result of combining the cumulative right-associative result of the f operation over the A elements.

    Definition Classes
    Foldable
    See also

    reduceLeftOption for a left-associative alternative

    Reducible#reduceRight for a version that doesn't need to return an Option for structures that are guaranteed to be non-empty. Example:

    scala> import cats.implicits._
    scala> val l = List(6, 3, 2)
    This is eqivalent to 6 - (3 - 2)
    scala> Foldable[List].reduceRightOption(l)((current, rest) => rest.map(current - _)).value
    res0: Option[Int] = Some(5)
    
    scala> Foldable[List].reduceRightOption(List.empty[Int])((current, rest) => rest.map(current - _)).value
    res1: Option[Int] = None
  75. def reduceRightToOption[A, B](fa: F[A])(f: (A) ⇒ B)(g: (A, Eval[B]) ⇒ Eval[B]): Eval[Option[B]]

    Overridden from Foldable for efficiency.

    Overridden from Foldable for efficiency.

    Definition Classes
    ReducibleFoldable
  76. def sequence[G[_], A](fga: F[G[A]])(implicit arg0: Applicative[G]): G[F[A]]

    Thread all the G effects through the F structure to invert the structure from F[G[A]] to G[F[A]].

    Thread all the G effects through the F structure to invert the structure from F[G[A]] to G[F[A]].

    Example:

    scala> import cats.implicits._
    scala> val x: List[Option[Int]] = List(Some(1), Some(2))
    scala> val y: List[Option[Int]] = List(None, Some(2))
    scala> x.sequence
    res0: Option[List[Int]] = Some(List(1, 2))
    scala> y.sequence
    res1: Option[List[Int]] = None
    Definition Classes
    Traverse
  77. def sequence_[G[_], A](fga: F[G[A]])(implicit arg0: Applicative[G]): G[Unit]

    Sequence F[G[A]] using Applicative[G].

    Sequence F[G[A]] using Applicative[G].

    This is similar to traverse_ except it operates on F[G[A]] values, so no additional functions are needed.

    For example:

    scala> import cats.implicits._
    scala> val F = Foldable[List]
    scala> F.sequence_(List(Option(1), Option(2), Option(3)))
    res0: Option[Unit] = Some(())
    scala> F.sequence_(List(Option(1), None, Option(3)))
    res1: Option[Unit] = None
    Definition Classes
    Foldable
  78. def size[A](fa: F[A]): Long

    The size of this UnorderedFoldable.

    The size of this UnorderedFoldable.

    This is overridden in structures that have more efficient size implementations (e.g. Vector, Set, Map).

    Note: will not terminate for infinite-sized collections.

    Definition Classes
    UnorderedFoldable
  79. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  80. def takeWhile_[A](fa: F[A])(p: (A) ⇒ Boolean): List[A]

    Convert F[A] to a List[A], retaining only initial elements which match p.

    Convert F[A] to a List[A], retaining only initial elements which match p.

    Definition Classes
    Foldable
  81. def toList[A](fa: F[A]): List[A]

    Convert F[A] to a List[A].

    Convert F[A] to a List[A].

    Definition Classes
    Foldable
  82. def toNonEmptyList[A](fa: F[A]): NonEmptyList[A]
    Definition Classes
    Reducible
  83. def toString(): String
    Definition Classes
    AnyRef → Any
  84. def traverse[G[_], A, B](fa: F[A])(f: (A) ⇒ G[B])(implicit arg0: Applicative[G]): G[F[B]]

    Given a function which returns a G effect, thread this effect through the running of this function on all the values in F, returning an F[B] in a G context.

    Given a function which returns a G effect, thread this effect through the running of this function on all the values in F, returning an F[B] in a G context.

    Example:

    scala> import cats.implicits._
    scala> def parseInt(s: String): Option[Int] = Either.catchOnly[NumberFormatException](s.toInt).toOption
    scala> List("1", "2", "3").traverse(parseInt)
    res0: Option[List[Int]] = Some(List(1, 2, 3))
    scala> List("1", "two", "3").traverse(parseInt)
    res1: Option[List[Int]] = None
    Definition Classes
    NonEmptyTraverseTraverse
  85. def traverseWithIndexM[G[_], A, B](fa: F[A])(f: (A, Int) ⇒ G[B])(implicit G: Monad[G]): G[F[B]]

    Akin to traverse, but also provides the value's index in structure F when calling the function.

    Akin to traverse, but also provides the value's index in structure F when calling the function.

    This performs the traversal in a single pass but requires that effect G is monadic. An applicative traversal can be performed in two passes using zipWithIndex followed by traverse.

    Definition Classes
    Traverse
  86. def traverse_[G[_], A, B](fa: F[A])(f: (A) ⇒ G[B])(implicit G: Applicative[G]): G[Unit]

    Traverse F[A] using Applicative[G].

    Traverse F[A] using Applicative[G].

    A values will be mapped into G[B] and combined using Applicative#map2.

    For example:

    scala> import cats.implicits._
    scala> def parseInt(s: String): Option[Int] = Either.catchOnly[NumberFormatException](s.toInt).toOption
    scala> val F = Foldable[List]
    scala> F.traverse_(List("333", "444"))(parseInt)
    res0: Option[Unit] = Some(())
    scala> F.traverse_(List("333", "zzz"))(parseInt)
    res1: Option[Unit] = None

    This method is primarily useful when G[_] represents an action or effect, and the specific A aspect of G[A] is not otherwise needed.

    Definition Classes
    Foldable
  87. 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.Functor
    scala> import cats.implicits.catsStdInstancesForQueue
    
    scala> Functor[Queue].tupleLeft(Queue("hello", "world"), 42)
    res0: scala.collection.immutable.Queue[(Int, String)] = Queue((42,hello), (42,world))
    Definition Classes
    Functor
  88. 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.Functor
    scala> import cats.implicits.catsStdInstancesForQueue
    
    scala> Functor[Queue].tupleRight(Queue("hello", "world"), 42)
    res0: scala.collection.immutable.Queue[(String, Int)] = Queue((hello,42), (world,42))
    Definition Classes
    Functor
  89. def unorderedFold[A](fa: F[A])(implicit arg0: CommutativeMonoid[A]): A
    Definition Classes
    FoldableUnorderedFoldable
  90. def unorderedFoldMap[A, B](fa: F[A])(f: (A) ⇒ B)(implicit arg0: CommutativeMonoid[B]): B
    Definition Classes
    FoldableUnorderedFoldable
  91. def unorderedSequence[G[_], A](fga: F[G[A]])(implicit arg0: CommutativeApplicative[G]): G[F[A]]
    Definition Classes
    TraverseUnorderedTraverse
  92. def unorderedTraverse[G[_], A, B](sa: F[A])(f: (A) ⇒ G[B])(implicit arg0: CommutativeApplicative[G]): G[F[B]]
    Definition Classes
    TraverseUnorderedTraverse
  93. 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.Functor
    scala> import cats.implicits.catsStdInstancesForList
    
    scala> Functor[List].void(List(1,2,3))
    res0: List[Unit] = List((), (), ())
    Definition Classes
    Functor
  94. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  95. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  96. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @native() @throws( ... )
  97. 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.Functor
    scala> import cats.implicits.catsStdInstancesForOption
    
    scala> val s = Some(42)
    scala> Functor[Option].widen(s)
    res0: Option[Int] = Some(42)
    Definition Classes
    Functor
  98. def zipWithIndex[A](fa: F[A]): F[(A, Int)]

    Traverses through the structure F, pairing the values with assigned indices.

    Traverses through the structure F, pairing the values with assigned indices.

    The behavior is consistent with the Scala collection library's zipWithIndex for collections such as List.

    Definition Classes
    Traverse

Inherited from Reducible[F]

Inherited from Traverse[F]

Inherited from UnorderedTraverse[F]

Inherited from Foldable[F]

Inherited from UnorderedFoldable[F]

Inherited from Functor[F]

Inherited from Invariant[F]

Inherited from Serializable

Inherited from Serializable

Inherited from AnyRef

Inherited from Any

Ungrouped