Class

scala.util

Left

Related Doc: package util

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final case class Left[+A, +B](a: A) extends Either[A, B] with Product with Serializable

The left side of the disjoint union, as opposed to the scala.util.Right side.

Source
Either.scala
Version

1.0, 11/10/2008

Linear Supertypes
Serializable, java.io.Serializable, Product, Equals, Either[A, B], AnyRef, Any
Ordering
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  2. By Inheritance
Inherited
  1. Left
  2. Serializable
  3. Serializable
  4. Product
  5. Equals
  6. Either
  7. AnyRef
  8. Any
Implicitly
  1. by MergeableEither
  2. by any2stringadd
  3. by StringFormat
  4. by Ensuring
  5. by ArrowAssoc
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Visibility
  1. Public
  2. All

Instance Constructors

  1. new Left(a: A)

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Value Members

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

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    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

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    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. def +(other: String): String

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    Implicit information
    This member is added by an implicit conversion from Left[A, B] to any2stringadd[Left[A, B]] performed by method any2stringadd in scala.Predef.
    Definition Classes
    any2stringadd
  4. def ->[B](y: B): (Left[A, B], B)

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    Implicit information
    This member is added by an implicit conversion from Left[A, B] to ArrowAssoc[Left[A, B]] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @inline()
  5. final def ==(arg0: Any): Boolean

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    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
  6. val a: A

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  7. final def asInstanceOf[T0]: T0

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    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.

  8. def clone(): AnyRef

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    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

  9. def ensuring(cond: (Left[A, B]) ⇒ Boolean, msg: ⇒ Any): Left[A, B]

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    Implicit information
    This member is added by an implicit conversion from Left[A, B] to Ensuring[Left[A, B]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  10. def ensuring(cond: (Left[A, B]) ⇒ Boolean): Left[A, B]

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    Implicit information
    This member is added by an implicit conversion from Left[A, B] to Ensuring[Left[A, B]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  11. def ensuring(cond: Boolean, msg: ⇒ Any): Left[A, B]

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    Implicit information
    This member is added by an implicit conversion from Left[A, B] to Ensuring[Left[A, B]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  12. def ensuring(cond: Boolean): Left[A, B]

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    Implicit information
    This member is added by an implicit conversion from Left[A, B] to Ensuring[Left[A, B]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  13. final def eq(arg0: AnyRef): Boolean

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    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
  14. def finalize(): Unit

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    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

  15. def fold[X](fa: (A) ⇒ X, fb: (B) ⇒ X): X

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    Applies fa if this is a Left or fb if this is a Right.

    Applies fa if this is a Left or fb if this is a Right.

    fa

    the function to apply if this is a Left

    fb

    the function to apply if this is a Right

    returns

    the results of applying the function

    Definition Classes
    Either
    Example:
    1. val result: Either[Exception, Value] = possiblyFailingOperation()
      log(result.fold(
        ex => "Operation failed with " + ex,
        v => "Operation produced value: " + v
      ))
  16. def formatted(fmtstr: String): String

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    Returns string formatted according to given format string.

    Returns string formatted according to given format string. Format strings are as for String.format (@see java.lang.String.format).

    Implicit information
    This member is added by an implicit conversion from Left[A, B] to StringFormat[Left[A, B]] performed by method StringFormat in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @inline()
  17. final def getClass(): Class[_]

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    A representation that corresponds to the dynamic class of the receiver object.

    A representation that corresponds to the dynamic class of the receiver object.

    The nature of the representation is platform dependent.

    returns

    a representation that corresponds to the dynamic class of the receiver object.

    Definition Classes
    AnyRef → Any
    Note

    not specified by SLS as a member of AnyRef

  18. final def isInstanceOf[T0]: Boolean

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    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
  19. def isLeft: Boolean

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    Returns true if this is a Left, false otherwise.

    Returns true if this is a Left, false otherwise.

    Left("tulip").isLeft // true
    Right("venus fly-trap").isLeft // false
    Definition Classes
    LeftEither
  20. def isRight: Boolean

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    Returns true if this is a Right, false otherwise.

    Returns true if this is a Right, false otherwise.

    Left("tulip").isRight // false
    Right("venus fly-trap").isRight // true
    Definition Classes
    LeftEither
  21. def joinLeft[A1 >: A, B1 >: B, C](implicit ev: <:<[A1, Either[C, B1]]): Either[C, B1]

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    Joins an Either through Left.

    Joins an Either through Left.

    This method requires that the left side of this Either is itself an Either type. That is, this must be some type like:

    Either[Either[C, B], B]

    (which respects the type parameter bounds, shown below.)

    If this instance is a Left[Either[C, B]] then the contained Either[C, B] will be returned, otherwise this value will be returned unmodified.

    Left[Either[Int, String], String](Right("flower")).joinLeft // Result: Right("flower")
    Left[Either[Int, String], String](Left(12)).joinLeft // Result: Left(12)
    Right[Either[Int, String], String]("daisy").joinLeft // Result: Right("daisy")

    This method, and joinRight, are analogous to Option#flatten

    Definition Classes
    Either
  22. def joinRight[A1 >: A, B1 >: B, C](implicit ev: <:<[B1, Either[A1, C]]): Either[A1, C]

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    Joins an Either through Right.

    Joins an Either through Right.

    This method requires that the right side of this Either is itself an Either type. That is, this must be some type like:

    Either[A, Either[A, C]]

    (which respects the type parameter bounds, shown below.)

    If this instance is a Right[Either[A, C]] then the contained Either[A, C] will be returned, otherwise this value will be returned unmodified.

    Definition Classes
    Either
    Example:
    1. Right[String, Either[String, Int]](Right(12)).joinRight // Result: Right(12)
      Right[String, Either[String, Int]](Left("flower")).joinRight // Result: Left("flower")
      Left[String, Either[String, Int]]("flower").joinRight // Result: Left("flower")

      This method, and joinLeft, are analogous to Option#flatten

  23. def left: LeftProjection[A, B]

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    Projects this Either as a Left.

    Projects this Either as a Left.

    Definition Classes
    Either
  24. def merge: B

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    Implicit information
    This member is added by an implicit conversion from Left[A, B] to MergeableEither[B] performed by method MergeableEither in scala.util.Either.
    Definition Classes
    MergeableEither
  25. final def ne(arg0: AnyRef): Boolean

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    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
  26. final def notify(): Unit

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    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

  27. final def notifyAll(): Unit

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    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

  28. def right: RightProjection[A, B]

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    Projects this Either as a Right.

    Projects this Either as a Right.

    Definition Classes
    Either
  29. def swap: Serializable with Product with Either[B, A]

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    If this is a Left, then return the left value in Right or vice versa.

    If this is a Left, then return the left value in Right or vice versa.

    Definition Classes
    Either
    Example:
    1. val l: Either[String, Int] = Left("left")
      val r: Either[Int, String] = l.swap // Result: Right("left")
  30. final def synchronized[T0](arg0: ⇒ T0): T0

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    Definition Classes
    AnyRef
  31. final def wait(): Unit

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    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  32. final def wait(arg0: Long, arg1: Int): Unit

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

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    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  34. def [B](y: B): (Left[A, B], B)

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    Implicit information
    This member is added by an implicit conversion from Left[A, B] to ArrowAssoc[Left[A, B]] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc