Packages

package root

Definition Classes: root

package cats

The cats root package contains all the trait signatures of most Scala type classes.

Cats type classes are implemented using the approach from the Type classes as objects and implicits article.

For each type class, cats provides three pieces: - Its signature: a trait that is polymorphic on a type parameter. Type class traits inherit from other type classes to indicate that any implementation of the lower type class (e.g. Applicative) can also serve as an instance for the higuer type class (e.g. Functor). - Type class 'instances, which are classes and objects that implement one or more type class signatures for some specific types. Type class instances for several data types from the Java or Scala standard libraries are declared in the subpackage cats.instances. - Syntax extensions, each of which provides the methods of the type class defines as extension methods (which in Scala 2 are encoded as implicit classes) for values of any type F; given that an instance of the type class for the receiver type (this) is in the implicit scope. Symtax extensions are declared in the cats.syntax package. - A set of laws, that are also generic on the type of the class, and are only defined on the operations of the type class. The purpose of these laws is to declare some algebraic relations (equations) between Scala expressions involving the operations of the type class, and test (but not verify) that implemented instances satisfy those equations. Laws are defined in the cats-laws package.

Although most of cats type classes are declared in this package, some are declared in other packages: - type classes that operate on base types (kind *), and their implementations for standard library types, are contained in cats.kernel, which is a different SBT project. However, they are re-exported from this package. - type classes of kind F[_, _], such as cats.arrow.Profunctor" or cats.arrow.Arrow, which are relevant for Functional Reactive Programming or optics, are declared in the cats.arrow package. - Also, those type classes that abstract over (pure or impure) functional runtime effects are declared in the cats-effect library. - Some type classes for which no laws can be provided are left out of the main road, in a small and dirty alley. These are the alleycats.

Definition Classes: root

package data

Definition Classes: cats

AndThen

AppFunc

Binested

BinestedBifoldable

BinestedBitraverse

BinestedInstances

Chain

Cokleisli

Const

Cont

ContT

EitherK

EitherT

Func

IdT

IndexedReaderWriterStateT

IndexedState

IndexedStateT

Ior

IorT

Kleisli

KleisliFromFunctionPartiallyApplied

Nested

NonEmptyChainOps

NonEmptyList

NonEmptyMapOps

NonEmptySeq

NonEmptySetOps

NonEmptyVector

OneAnd

OptionT

Reader

ReaderWriterState

ReaderWriterStateT

RepresentableStore

RepresentableStoreT

RepresentableStoreTInstances1

RepresentableStoreTInstances2

State

StateT

Store

StoreT

Tuple2K

Validated

Writer

WriterT

ZipList

ZipSeq

ZipStream

ZipVector

cats.data

Nested

Companion object Nested

final case class Nested[F[_], G[_], A](value: F[G[A]]) extends Product with Serializable

Similar to cats.data.Tuple2K, but for nested composition.

For instance, since both List and Option have a Functor, then so does List[Option[_]]. This is represented by this data type via the instantiation Nested[List, Option, *].

scala> import cats.Functor
scala> import cats.data.Nested
scala> import cats.implicits._
scala> val listOption: List[Option[Int]] = List(Some(1), None)
scala> val f: Int => String = i => (i * 2).toString
scala> Functor[List].map(listOption)(opt => opt.map(f))
res0: List[Option[String]] = List(Some(2), None)
scala> val nested: Nested[List, Option, Int] = Nested(listOption)
scala> val result: Nested[List, Option, String] = Functor[Nested[List, Option, *]].map(nested)(f)
scala> result.value
res1: List[Option[String]] = List(Some(2), None)

Source: Nested.scala

Linear Supertypes

Serializable, Serializable, Product, Equals, AnyRef, Any

Type Hierarchy

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Inherited

Nested
Serializable
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Any

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Instance Constructors

new Nested(value: F[G[A]])

Value Members

final def !=(arg0: Any): Boolean

Definition Classes
AnyRef → Any
final def ##(): Int

Definition Classes
AnyRef → Any
final def ==(arg0: Any): Boolean

Definition Classes
AnyRef → Any
final def asInstanceOf[T0]: T0

Definition Classes
Any
def clone(): AnyRef

Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws( ... ) @native() @IntrinsicCandidate()
final def eq(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def getClass(): Class[_]

Definition Classes
AnyRef → Any
Annotations
@native() @IntrinsicCandidate()
final def isInstanceOf[T0]: Boolean

Definition Classes
Any
def mapK[H[_]](f: ~>[F, H]): Nested[H, G, A]
Modify the context F using transformation f.
final def ne(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def notify(): Unit

Definition Classes
AnyRef
Annotations
@native() @IntrinsicCandidate()
final def notifyAll(): Unit

Definition Classes
AnyRef
Annotations
@native() @IntrinsicCandidate()
final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef
val value: F[G[A]]
final def wait(arg0: Long, arg1: Int): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def wait(arg0: Long): Unit

Definition Classes
AnyRef
Annotations
@throws( ... ) @native()
final def wait(): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )

Deprecated Value Members

def finalize(): Unit

Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws( classOf[java.lang.Throwable] ) @Deprecated
Deprecated

Packages

Nested

Companion object Nested

final case class Nested[F[_], G[_], A](value: F[G[A]]) extends Product with Serializable

Instance Constructors

Value Members

Deprecated Value Members

Inherited from Serializable

Inherited from Serializable

Inherited from Product

Inherited from Equals

Inherited from AnyRef

Inherited from Any

Ungrouped

Packages

Nested 

Companion object Nested

final case class Nested[F[_], G[_], A](value: F[G[A]]) extends Product with Serializable

Instance Constructors

Value Members

Deprecated Value Members

Inherited from Serializable

Inherited from Serializable

Inherited from Product

Inherited from Equals

Inherited from AnyRef

Inherited from Any

Ungrouped

Nested