Packages

  • package root
    Definition Classes
    root
  • package cats

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

    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 higher 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. Syntax 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
  • object Eval extends EvalInstances with Serializable
    Definition Classes
    cats
  • Defer
  • FlatMap
  • Leaf

sealed abstract class Leaf[A] extends Eval[A]

A Leaf does not depend on any other Eval so calling .value does not trigger any flatMaps or defers

Source
Eval.scala
Linear Supertypes
Eval[A], Serializable, AnyRef, Any
Known Subclasses
Always, Later, Now
Type Hierarchy
Ordering
  1. Alphabetic
  2. By Inheritance
Inherited
  1. Leaf
  2. Eval
  3. Serializable
  4. AnyRef
  5. Any
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Visibility
  1. Public
  2. Protected

Abstract Value Members

  1. abstract def memoize: Eval[A]

    Ensure that the result of the computation (if any) will be memoized.

    Ensure that the result of the computation (if any) will be memoized.

    Practically, this means that when called on an Always[A] a Later[A] with an equivalent computation will be returned.

    Definition Classes
    Eval
  2. abstract def value: A

    Evaluate the computation and return an A value.

    Evaluate the computation and return an A value.

    For lazy instances (Later, Always), any necessary computation will be performed at this point. For eager instances (Now), a value will be immediately returned.

    Definition Classes
    Eval

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(classOf[java.lang.CloneNotSupportedException]) @native()
  6. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  7. def equals(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef → Any
  8. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.Throwable])
  9. def flatMap[B](f: (A) => Eval[B]): Eval[B]

    Lazily perform a computation based on an Eval[A], using the function f to produce an Eval[B] given an A.

    Lazily perform a computation based on an Eval[A], using the function f to produce an Eval[B] given an A.

    This call is stack-safe -- many .flatMap calls may be chained without consumed additional stack during evaluation. It is also written to avoid left-association problems, so that repeated calls to .flatMap will be efficiently applied.

    Computation performed in f is always lazy, even when called on an eager (Now) instance.

    Definition Classes
    Eval
  10. final def getClass(): Class[_ <: AnyRef]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  11. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  12. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  13. def map[B](f: (A) => B): Eval[B]

    Transform an Eval[A] into an Eval[B] given the transformation function f.

    Transform an Eval[A] into an Eval[B] given the transformation function f.

    This call is stack-safe -- many .map calls may be chained without consumed additional stack during evaluation.

    Computation performed in f is always lazy, even when called on an eager (Now) instance.

    Definition Classes
    Eval
  14. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  15. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  16. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  17. final def synchronized[T0](arg0: => T0): T0
    Definition Classes
    AnyRef
  18. def toString(): String
    Definition Classes
    AnyRef → Any
  19. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  20. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  21. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException]) @native()

Inherited from Eval[A]

Inherited from Serializable

Inherited from AnyRef

Inherited from Any

Ungrouped