Packages

object Either extends Serializable

Source
Either.scala
Linear Supertypes
Serializable, java.io.Serializable, AnyRef, Any
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Type Members

  1. implicit final class MergeableEither [A] extends AnyVal

    Allows use of a merge method to extract values from Either instances regardless of whether they are Left or Right.

    Allows use of a merge method to extract values from Either instances regardless of whether they are Left or Right.

    val l = Left(List(1)): Either[List[Int], Vector[Int]]
    val r = Right(Vector(1)): Either[List[Int], Vector[Int]]
    l.merge: Seq[Int] // List(1)
    r.merge: Seq[Int] // Vector(1)
  2. final case class LeftProjection [+A, +B](e: Either[A, B]) extends Product with Serializable

    Projects an Either into a Left.

    Projects an Either into a Left.

    This allows for-comprehensions over Either instances - for example

    for (s <- Left("flower").left) yield s.length // Left(6)

    Continuing the analogy with scala.Option, a LeftProjection declares that Left should be analogous to Some in some code.

    // using Option:
    def interactWithDB(x: Query): Option[Result] =
      try {
        Some(getResultFromDatabase(x))
      } catch {
        case ex => None
      }
    
    // this will only be executed if interactWithDB returns a Some
    val report =
      for (r <- interactWithDB(someQuery)) yield generateReport(r)
    if (report.isDefined)
      send(report)
    else
      log("report not generated, not sure why...")
    // using Either
    def interactWithDB(x: Query): Either[Exception, Result] =
      try {
        Right(getResultFromDatabase(x))
      } catch {
        case ex => Left(ex)
      }
    
    // this will only be executed if interactWithDB returns a Right
    val report =
      for (r <- interactWithDB(someQuery).right) yield generateReport(r)
    if (report.isRight)
      send(report)
    else
      log("report not generated, reason was " + report.left.get)
    Annotations
    @deprecated
    Deprecated

    (Since version 2.12.0) use swap instead

    Version

    1.0, 11/10/2008

  3. final case class RightProjection [+A, +B](e: Either[A, B]) extends Product with Serializable

    Projects an Either into a Right.

    Projects an Either into a Right.

    This allows for-comprehensions over Either instances - for example

    for (s <- Right("flower").right) yield s.length // Right(6)

    Continuing the analogy with scala.Option, a RightProjection declares that Right should be analogous to Some in some code.

    Analogous to LeftProjection, see example usage in its documentation above.

    Annotations
    @deprecated
    Deprecated

    (Since version 2.12.0) Either is now right-biased

    Version

    1.0, 11/10/2008

Value Members

  1. final def !=(arg0: Any): Boolean

    Test two objects for inequality.

    Test two objects for inequality.

    returns

    true if !(this == that), false otherwise.

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

    Equivalent to x.hashCode except for boxed numeric types and null.

    Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.

    returns

    a hash value consistent with ==

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

    The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).

    The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).

    returns

    true if the receiver object is equivalent to the argument; false otherwise.

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

    Cast the receiver object to be of type T0.

    Cast the receiver object to be of type T0.

    Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression 1.asInstanceOf[String] will throw a ClassCastException at runtime, while the expression List(1).asInstanceOf[List[String]] will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

    returns

    the receiver object.

    Definition Classes
    Any
    Exceptions thrown

    ClassCastException if the receiver object is not an instance of the erasure of type T0.

  5. def clone(): AnyRef

    Create a copy of the receiver object.

    Create a copy of the receiver object.

    The default implementation of the clone method is platform dependent.

    returns

    a copy of the receiver object.

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
    Note

    not specified by SLS as a member of AnyRef

  6. def cond[X, Y](test: Boolean, right: ⇒ Y, left: ⇒ X): Either[X, Y]

    If the condition is satisfied, return the given B in Right, otherwise, return the given A in Left.

    If the condition is satisfied, return the given B in Right, otherwise, return the given A in Left.

    val userInput: String = ...
    Either.cond(
      userInput.forall(_.isDigit) && userInput.size == 10,
      PhoneNumber(userInput),
      "The input (%s) does not look like a phone number".format(userInput)
  7. final def eq(arg0: AnyRef): Boolean

    Tests whether the argument (that) is a reference to the receiver object (this).

    Tests whether the argument (that) is a reference to the receiver object (this).

    The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional properties:

    • It is consistent: for any non-null instances x and y of type AnyRef, multiple invocations of x.eq(y) consistently returns true or consistently returns false.
    • For any non-null instance x of type AnyRef, x.eq(null) and null.eq(x) returns false.
    • null.eq(null) returns true.

    When overriding the equals or hashCode methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).

    returns

    true if the argument is a reference to the receiver object; false otherwise.

    Definition Classes
    AnyRef
  8. def equals(arg0: Any): Boolean

    The equality method for reference types.

    The equality method for reference types. Default implementation delegates to eq.

    See also equals in scala.Any.

    returns

    true if the receiver object is equivalent to the argument; false otherwise.

    Definition Classes
    AnyRef → Any
  9. def finalize(): Unit

    Called by the garbage collector on the receiver object when there are no more references to the object.

    Called by the garbage collector on the receiver object when there are no more references to the object.

    The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.

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

    not specified by SLS as a member of AnyRef

  10. final def getClass(): Class[_]

    Returns the runtime class representation of the object.

    Returns the runtime class representation of the object.

    returns

    a class object corresponding to the runtime type of the receiver.

    Definition Classes
    AnyRef → Any
  11. def hashCode(): Int

    The hashCode method for reference types.

    The hashCode method for reference types. See hashCode in scala.Any.

    returns

    the hash code value for this object.

    Definition Classes
    AnyRef → Any
  12. final def isInstanceOf[T0]: Boolean

    Test whether the dynamic type of the receiver object is T0.

    Test whether the dynamic type of the receiver object is T0.

    Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression 1.isInstanceOf[String] will return false, while the expression List(1).isInstanceOf[List[String]] will return true. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

    returns

    true if the receiver object is an instance of erasure of type T0; false otherwise.

    Definition Classes
    Any
  13. final def ne(arg0: AnyRef): Boolean

    Equivalent to !(this eq that).

    Equivalent to !(this eq that).

    returns

    true if the argument is not a reference to the receiver object; false otherwise.

    Definition Classes
    AnyRef
  14. final def notify(): Unit

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Definition Classes
    AnyRef
    Note

    not specified by SLS as a member of AnyRef

  15. final def notifyAll(): Unit

    Wakes up all threads that are waiting on the receiver object's monitor.

    Wakes up all threads that are waiting on the receiver object's monitor.

    Definition Classes
    AnyRef
    Note

    not specified by SLS as a member of AnyRef

  16. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  17. def toString(): String

    Creates a String representation of this object.

    Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.

    returns

    a String representation of the object.

    Definition Classes
    AnyRef → Any
  18. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  19. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  20. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )

Inherited from Serializable

Inherited from java.io.Serializable

Inherited from AnyRef

Inherited from Any

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