scala.util

# Left

#### 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.

Version

  1.0, 11/10/2008

Linear Supertypes
Serializable, java.io.Serializable, Product, Equals, Either[A, B], AnyRef, Any
Type Hierarchy Learn more about scaladoc diagrams
Ordering

1. Alphabetic
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

1. Hide All
2. Show all

Learn more about member selection
Visibility

1. Public
2. All

### Instance Constructors

1. #### new Left(a: A)

### Value Members

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

   Definition Classes
     AnyRef → Any

2. #### final def ##(): Int

   Definition Classes
     AnyRef → Any

3. #### def +(other: String): String

   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)

   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

   Definition Classes
     AnyRef → Any

6. #### val a: A

7. #### final def asInstanceOf[T0]: T0

   Definition Classes
     Any

8. #### def clone(): AnyRef

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

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

   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]

    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]

    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]

    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

    Definition Classes
      AnyRef

14. #### def finalize(): Unit

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

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

    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

    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[_]

    Definition Classes
      AnyRef → Any

18. #### final def isInstanceOf[T0]: Boolean

    Definition Classes
      Any

19. #### def isLeft: Boolean

    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
      Left → Either

20. #### def isRight: Boolean

    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
      Left → Either

21. #### def joinLeft[A1 >: A, B1 >: B, C](implicit ev: <:<[A1, Either[C, B1]]): Either[C, B1]

    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]

    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]

    Projects this `Either` as a `Left`.

    Projects this `Either` as a `Left`.

    Definition Classes
      Either

24. #### def merge: B

    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

    Definition Classes
      AnyRef

26. #### final def notify(): Unit

    Definition Classes
      AnyRef

27. #### final def notifyAll(): Unit

    Definition Classes
      AnyRef

28. #### def right: RightProjection[A, B]

    Projects this `Either` as a `Right`.

    Projects this `Either` as a `Right`.

    Definition Classes
      Either

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

    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

    Definition Classes
      AnyRef

31. #### final def wait(): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

32. #### final def wait(arg0: Long, arg1: Int): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

33. #### final def wait(arg0: Long): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

34. #### def →[B](y: B): (Left[A, B], B)

    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

### Inherited from Serializable

### Inherited from java.io.Serializable

### Inherited from Product

### Inherited from Equals

### Inherited from Either[A, B]

### Inherited from AnyRef

### Inherited from Any

### Inherited by implicit conversion MergeableEither from Left[A, B] to MergeableEither[B]

### Inherited by implicit conversion any2stringadd from Left[A, B] to any2stringadd[Left[A, B]]

### Inherited by implicit conversion StringFormat from Left[A, B] to StringFormat[Left[A, B]]

### Inherited by implicit conversion Ensuring from Left[A, B] to Ensuring[Left[A, B]]

### Inherited by implicit conversion ArrowAssoc from Left[A, B] to ArrowAssoc[Left[A, B]]

### Ungrouped