ParseableHeaderInstances
Attributes
- Source
- ParseableHeader.scala
- Graph
-
- Supertypes
-
trait SemigroupK[ParseableHeader]trait Functor[ParseableHeader]trait Invariant[ParseableHeader]trait Serializableclass Objecttrait Matchableclass AnyShow all
- Self type
Members list
Value members
Concrete methods
Combine two F[A] values.
Combine two F[A] values.
Example:
scala> import cats.syntax.all._
scala> SemigroupK[List].combineK(List(1, 2), List(3, 4))
res0: List[Int] = List(1, 2, 3, 4)
Attributes
- Definition Classes
- Source
- ParseableHeader.scala
Attributes
- Definition Classes
- Source
- ParseableHeader.scala
Inherited methods
Given a type A, create a concrete Semigroup[F[A]].
Given a type A, create a concrete Semigroup[F[A]].
Example:
scala> import cats.syntax.all._
scala> val s: Semigroup[List[Int]] = SemigroupK[List].algebra[Int]
Attributes
- Inherited from:
- SemigroupK
- Source
- SemigroupK.scala
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)
Attributes
- Inherited from:
- Functor
- Source
- Functor.scala
Given a sequence of as, combine them and return the total.
Given a sequence of as, combine them and return the total.
If the sequence is empty, returns None. Otherwise, returns Some(total).
Example:
scala> SemigroupK[List].combineAllOptionK(List(List("One"), List("Two"), List("Three")))
res0: Option[List[String]] = Some(List(One, Two, Three))
scala> SemigroupK[List].combineAllOptionK[String](List.empty)
res1: Option[List[String]] = None
Attributes
- Inherited from:
- SemigroupK
- Source
- SemigroupK.scala
Similar to combineK but uses Eval to allow for laziness in the second argument. This can allow for "short-circuiting" of computations.
NOTE: the default implementation of combineKEval does not short-circuit computations. For data structures that can benefit from laziness, SemigroupK instances should override this method.
In the following example, x.combineK(bomb) would result in an error, but combineKEval "short-circuits" the computation. x is Some and thus the result of bomb doesn't even need to be evaluated in order to determine that the result of combineKEval should be x.
scala> import cats.{Eval, Later}
scala> import cats.syntax.all._
scala> val bomb: Eval[Option[Int]] = Later(sys.error("boom"))
scala> val x: Option[Int] = Some(42)
scala> x.combineKEval(bomb).value
res0: Option[Int] = Some(42)
Attributes
- Inherited from:
- SemigroupK
- Source
- SemigroupK.scala
Return a combined with itself n times.
Return a combined with itself n times.
Example:
scala> SemigroupK[List].combineNK(List(1), 5)
res0: List[Int] = List(1, 1, 1, 1, 1)
Attributes
- Inherited from:
- SemigroupK
- Source
- SemigroupK.scala
"Compose" with a G[_] type to form a SemigroupK for λ[α => F[G[α]]].
"Compose" with a G[_] type to form a SemigroupK for λ[α => F[G[α]]]. Note that this universally works for any G, because the "inner" structure isn't considered when combining two instances.
Example:
scala> import cats.syntax.all._
scala> type ListOption[A] = List[Option[A]]
scala> val s: SemigroupK[ListOption] = SemigroupK[List].compose[Option]
scala> s.combineK(List(Some(1), None, Some(2)), List(Some(3), None))
res0: List[Option[Int]] = List(Some(1), None, Some(2), Some(3), None)
Attributes
- Inherited from:
- SemigroupK
- Source
- SemigroupK.scala
Attributes
- Inherited from:
- Functor
- Source
- Functor.scala
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)
Attributes
- Inherited from:
- Invariant
- Source
- Invariant.scala
Attributes
- Inherited from:
- Functor
- Source
- Functor.scala
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
Attributes
- Definition Classes
- Inherited from:
- Functor
- Source
- Functor.scala
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)
Attributes
- Inherited from:
- Invariant
- Source
- Invariant.scala
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!)
Attributes
- Inherited from:
- Functor
- Source
- Functor.scala
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))
Attributes
- Inherited from:
- Functor
- Source
- Functor.scala
Pair the result of function application with A.
Pair the result of function application with A.
Example:
scala> import cats.Functor
scala> import cats.implicits.catsStdInstancesForOption
scala> Functor[Option].fproductLeft(Option(42))(_.toString)
res0: Option[(String, Int)] = Some((42,42))
Attributes
- Inherited from:
- Functor
- Source
- Functor.scala
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)
Attributes
- Inherited from:
- Functor
- Source
- Functor.scala
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
Attributes
- Definition Classes
- Inherited from:
- Functor
- Source
- Functor.scala
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)
Attributes
- Inherited from:
- Functor
- Source
- Functor.scala
return a semigroupK that reverses the order so combineK(a, b) == reverse.combineK(b, a)
return a semigroupK that reverses the order so combineK(a, b) == reverse.combineK(b, a)
Attributes
- Inherited from:
- SemigroupK
- Source
- SemigroupK.scala
Combines F[A] and F[B] into a F[Either[A,B]]].
Combines F[A] and F[B] into a F[Either[A,B]]].
Example:
scala> import cats.SemigroupK
scala> import cats.data.NonEmptyList
scala> SemigroupK[NonEmptyList].sum(NonEmptyList.one("abc"), NonEmptyList.one(2))
res0: NonEmptyList[Either[String,Int]] = NonEmptyList(Left(abc), Right(2))
Attributes
- Inherited from:
- SemigroupK
- Source
- SemigroupK.scala
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))
Attributes
- Inherited from:
- Functor
- Source
- Functor.scala
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))
Attributes
- Inherited from:
- Functor
- Source
- Functor.scala
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))
Attributes
- Inherited from:
- Functor
- Source
- Functor.scala
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((), (), ())
Attributes
- Inherited from:
- Functor
- Source
- Functor.scala
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)
Attributes
- Inherited from:
- Functor
- Source
- Functor.scala