Packages

Definition Classes: root

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

IdT

IndexedReaderWriterStateT

Ior

KleisliFromFunctionPartiallyApplied

RepresentableStoreTInstances1

RepresentableStoreTInstances2

Const

Companion object Const

final case class Const[A, B](getConst: A) extends Product with Serializable

Const is a phantom type, it does not contain a value of its second type parameter B Const can be seen as a type level version of Function.const[A, B]: A => B => A

Source: Const.scala

Linear Supertypes

Serializable, Product, Equals, AnyRef, Any

Type Hierarchy

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Inherited

Const
Serializable
Product
Equals
AnyRef
Any

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Visibility

Public
Protected

Instance Constructors

new Const(getConst: 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
def ===(that: Const[A, B])(implicit A: Eq[A]): Boolean
final def asInstanceOf[T0]: T0
Definition Classes
Any
def clone(): AnyRef
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.CloneNotSupportedException]) @native()
def combine(that: Const[A, B])(implicit A: Semigroup[A]): Const[A, B]
def compare(that: Const[A, B])(implicit A: Order[A]): Int
final def eq(arg0: AnyRef): Boolean
Definition Classes
AnyRef
def finalize(): Unit
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.Throwable])
final def getClass(): Class[_ <: AnyRef]
Definition Classes
AnyRef → Any
Annotations
@native()
val getConst: A
final def isInstanceOf[T0]: Boolean
Definition Classes
Any
final def ne(arg0: AnyRef): Boolean
Definition Classes
AnyRef
final def notify(): Unit
Definition Classes
AnyRef
Annotations
@native()
final def notifyAll(): Unit
Definition Classes
AnyRef
Annotations
@native()
def partialCompare(that: Const[A, B])(implicit A: PartialOrder[A]): Double
def productElementNames: Iterator[String]
Definition Classes
Product
def retag[C]: Const[A, C]
changes the type of the second type parameter
def show(implicit A: Show[A]): String
final def synchronized[T0](arg0: => T0): T0
Definition Classes
AnyRef
def traverse[F[_], C](f: (B) => F[C])(implicit F: Applicative[F]): F[Const[A, C]]
final def wait(): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
final def wait(arg0: Long, arg1: Int): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
final def wait(arg0: Long): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException]) @native()

Packages

Const

Companion object Const

final case class Const[A, B](getConst: A) extends Product with Serializable

Instance Constructors

Value Members

Inherited from Serializable

Inherited from Product

Inherited from Equals

Inherited from AnyRef

Inherited from Any

Ungrouped

Packages

Const

Companion object Const

final case class Const[A, B](getConst: A) extends Product with Serializable

Instance Constructors

Value Members

Inherited from Serializable

Inherited from Product

Inherited from Equals

Inherited from AnyRef

Inherited from Any

Ungrouped

Const