\/ - scalaz.\/

Represents a disjunction: a result that is either an A or a B.

An instance of A \/ B is either a -\/[A] (aka a "left") or a \/-[B] (aka a "right").

A common use of a disjunction is to explicitly represent the possibility of failure in a result as opposed to throwing an exception. By convention, the left is used for errors and the right is reserved for successes. For example, a function that attempts to parse an integer from a string may have a return type of NumberFormatException \/ Int. However, since there is no need to actually throw an exception, the type (A) chosen for the "left" could be any type representing an error and has no need to actually extend Exception.

A \/ B is isomorphic to scala.Either[A, B], but \/ is right-biased, so methods such as map and flatMap apply only in the context of the "right" case. This right bias makes \/ more convenient to use than scala.Either in a monadic context. Methods such as swap, swapped, and leftMap provide functionality that scala.Either exposes through left projections.

A \/ B is also isomorphic to Validation[A, B]. The subtle but important difference is that Applicative instances for Validation accumulates errors ("lefts") while Applicative instances for \/ fail fast on the first "left" they evaluate. This fail-fast behavior allows \/ to have lawful Monad instances that are consistent with their Applicative instances, while Validation cannot.

Source: Either.scala

Linear Supertypes

Serializable, Serializable, Product, Equals, AnyRef, Any

Known Subclasses

-\/, \/-

Type Members

final class SwitchingDisjunction[X] extends AnyRef

Abstract Value Members

abstract def canEqual(that: Any): Boolean

Definition Classes
Equals
abstract def productArity: Int

Definition Classes
Product
abstract def productElement(n: Int): Any

Definition Classes
Product

Concrete Value Members

final def !=(arg0: Any): Boolean

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

Definition Classes
AnyRef → Any
def +++[AA >: A, BB >: B](x: ⇒ \/[AA, BB])(implicit M1: Semigroup[BB], M2: Semigroup[AA]): \/[AA, BB]

Sums up values inside disjunction, if both are left or right.
Sums up values inside disjunction, if both are left or right. Returns first left otherwise.
```
\/-(v1) +++ \/-(v2) → \/-(v1 + v2)
\/-(v1) +++ -\/(v2) → -\/(v2)
-\/(v1) +++ \/-(v2) → -\/(v1)
-\/(v1) +++ -\/(v2) → -\/(v1 + v2)
```
def :?>>[X](right: ⇒ X): SwitchingDisjunction[X]

If this disjunction is right, return the given X value, otherwise, return the X value given to the return value.
final def ==(arg0: Any): Boolean

Definition Classes
AnyRef → Any
def ===[AA >: A, BB >: B](x: \/[AA, BB])(implicit EA: Equal[AA], EB: Equal[BB]): Boolean

Compare two disjunction values for equality.
def @\?/[AA, BB](k: (Validation[A, B]) ⇒ Validation[AA, BB]): \/[AA, BB]

Run a validation function and back to disjunction again.
Run a validation function and back to disjunction again. Alias for validationed
def ap[AA >: A, C](f: ⇒ \/[AA, (B) ⇒ C]): \/[AA, C]

Apply a function in the environment of the right of this disjunction.
final def asInstanceOf[T0]: T0

Definition Classes
Any
def bimap[C, D](f: (A) ⇒ C, g: (B) ⇒ D): \/[C, D]

Binary functor map on this disjunction.
def bitraverse[F[_], C, D](f: (A) ⇒ F[C], g: (B) ⇒ F[D])(implicit arg0: Functor[F]): F[\/[C, D]]

Binary functor traverse on this disjunction.
def clone(): AnyRef

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( ... )
def compare[AA >: A, BB >: B](x: \/[AA, BB])(implicit EA: Order[AA], EB: Order[BB]): Ordering

Compare two disjunction values for ordering.
def ensure[AA >: A](onLeft: ⇒ AA)(f: (B) ⇒ Boolean): \/[AA, B]

Ensures that the right value of this disjunction satisfies the given predicate, or returns left with the given value.
final def eq(arg0: AnyRef): Boolean

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

Definition Classes
AnyRef → Any
def exists[BB >: B](p: (BB) ⇒ Boolean): Boolean

Return true if this disjunction is a right value satisfying the given predicate.
def filter[AA >: A](p: (B) ⇒ Boolean)(implicit M: Monoid[AA]): \/[AA, B]

Filter on the right of this disjunction.
def finalize(): Unit

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( classOf[java.lang.Throwable] )
def flatMap[AA >: A, D](g: (B) ⇒ \/[AA, D]): \/[AA, D]

Bind through the right of this disjunction.
def fold[X](l: (A) ⇒ X, r: (B) ⇒ X): X

Catamorphism.
Catamorphism. Run the first given function if left, otherwise, the second given function.
def foldRight[Z](z: ⇒ Z)(f: (B, ⇒ Z) ⇒ Z): Z

Fold on the right of this disjunction.
def forall[BB >: B](p: (BB) ⇒ Boolean): Boolean

Return true if this disjunction is a left value or the right value satisfies the given predicate.
def foreach(g: (B) ⇒ Unit): Unit

Run the side-effect on the right of this disjunction.
final def getClass(): Class[_]

Definition Classes
AnyRef → Any
def getOrElse[BB >: B](x: ⇒ BB): BB

Return the right value of this disjunction or the given default if left.
Return the right value of this disjunction or the given default if left. Alias for |
def hashCode(): Int

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

Definition Classes
Any
def isLeft: Boolean

Return true if this disjunction is left.
def isRight: Boolean

Return true if this disjunction is right.
def leftMap[C](f: (A) ⇒ C): \/[C, B]

Run the given function on the left value.
def loopl[AA >: A, BB >: B, X](left: (AA) ⇒ \/[X, \/[AA, BB]], right: (BB) ⇒ X): X

Spin in tail-position on the left value of this disjunction.
def loopr[AA >: A, BB >: B, X](left: (AA) ⇒ X, right: (BB) ⇒ \/[X, \/[AA, BB]]): X

Spin in tail-position on the right value of this disjunction.
def map[D](g: (B) ⇒ D): \/[A, D]

Map on the right of this disjunction.
def merge[AA >: A](implicit ev: <~<[B, AA]): AA

Return the value from whichever side of the disjunction is defined, given a commonly assignable type.
final def ne(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def notify(): Unit

Definition Classes
AnyRef
final def notifyAll(): Unit

Definition Classes
AnyRef
def orElse[C, BB >: B](x: ⇒ \/[C, BB]): \/[C, BB]

Return this if it is a right, otherwise, return the given value.
Return this if it is a right, otherwise, return the given value. Alias for |||
def productIterator: Iterator[Any]

Definition Classes
Product
def productPrefix: String

Definition Classes
Product
def recover[BB >: B](pf: PartialFunction[A, BB]): \/[A, BB]

Run the given function on the left and return right with the result.
def recoverWith[AA >: A, BB >: B](pf: PartialFunction[AA, \/[AA, BB]]): \/[AA, BB]

Run the given function on the left and return the result.
def show[AA >: A, BB >: B](implicit SA: Show[AA], SB: Show[BB]): Cord

Show for a disjunction value.
def swap: \/[B, A]

Flip the left/right values in this disjunction.
Flip the left/right values in this disjunction. Alias for unary_~
def swapped[AA, BB](k: (\/[B, A]) ⇒ \/[BB, AA]): \/[AA, BB]

Run the given function on this swapped value.
Run the given function on this swapped value. Alias for ~
final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef
def toEither: Either[A, B]

Convert to a core scala.Either at your own peril.
def toList: List[B]

Return an empty list or list with one element on the right of this disjunction.
def toMaybe[BB >: B]: Maybe[BB]

Return an empty maybe or option with one element on the right of this disjunction.
Return an empty maybe or option with one element on the right of this disjunction. Useful to sweep errors under the carpet.
def toOption: Option[B]

Return an empty option or option with one element on the right of this disjunction.
Return an empty option or option with one element on the right of this disjunction. Useful to sweep errors under the carpet.
def toStream: Stream[B]

Return an empty stream or stream with one element on the right of this disjunction.
def toString(): String

Definition Classes
AnyRef → Any
def toThese: \&/[A, B]

Convert to a These.
def traverse[F[_], AA >: A, D](g: (B) ⇒ F[D])(implicit arg0: Applicative[F]): F[\/[AA, D]]

Traverse on the right of this disjunction.
def unary_~: \/[B, A]

Flip the left/right values in this disjunction.
Flip the left/right values in this disjunction. Alias for swap
def validation: Validation[A, B]

Convert to a Validation.
def validationNel[AA >: A]: ValidationNel[AA, B]

Convert to a ValidationNel.
def validationed[AA, BB](k: (Validation[A, B]) ⇒ Validation[AA, BB]): \/[AA, BB]

Run a validation function and back to disjunction again.
Run a validation function and back to disjunction again. Alias for @\?/
def valueOr[BB >: B](x: (A) ⇒ BB): BB

Return the right value of this disjunction or run the given function on the left.
final def wait(): Unit

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

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

Definition Classes
AnyRef
Annotations
@throws( ... )
def |[BB >: B](x: ⇒ BB): BB

Return the right value of this disjunction or the given default if left.
Return the right value of this disjunction or the given default if left. Alias for getOrElse
def |||[C, BB >: B](x: ⇒ \/[C, BB]): \/[C, BB]

Return this if it is a right, otherwise, return the given value.
Return this if it is a right, otherwise, return the given value. Alias for orElse
def ~[AA, BB](k: (\/[B, A]) ⇒ \/[BB, AA]): \/[AA, BB]

Run the given function on this swapped value.
Run the given function on this swapped value. Alias for swapped

\/

Related Docs: object \/ | package scalaz

sealed abstract class \/[+A, +B] extends Product with Serializable

Type Members

final class SwitchingDisjunction[X] extends AnyRef

Abstract Value Members

abstract def canEqual(that: Any): Boolean

abstract def productArity: Int

abstract def productElement(n: Int): Any

Concrete Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

def +++[AA >: A, BB >: B](x: ⇒ \/[AA, BB])(implicit M1: Semigroup[BB], M2: Semigroup[AA]): \/[AA, BB]

def :?>>[X](right: ⇒ X): SwitchingDisjunction[X]

final def ==(arg0: Any): Boolean

def ===[AA >: A, BB >: B](x: \/[AA, BB])(implicit EA: Equal[AA], EB: Equal[BB]): Boolean

def @\?/[AA, BB](k: (Validation[A, B]) ⇒ Validation[AA, BB]): \/[AA, BB]

def ap[AA >: A, C](f: ⇒ \/[AA, (B) ⇒ C]): \/[AA, C]

final def asInstanceOf[T0]: T0

def bimap[C, D](f: (A) ⇒ C, g: (B) ⇒ D): \/[C, D]

def bitraverse[F[_], C, D](f: (A) ⇒ F[C], g: (B) ⇒ F[D])(implicit arg0: Functor[F]): F[\/[C, D]]

def clone(): AnyRef

def compare[AA >: A, BB >: B](x: \/[AA, BB])(implicit EA: Order[AA], EB: Order[BB]): Ordering

def ensure[AA >: A](onLeft: ⇒ AA)(f: (B) ⇒ Boolean): \/[AA, B]

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

def exists[BB >: B](p: (BB) ⇒ Boolean): Boolean

def filter[AA >: A](p: (B) ⇒ Boolean)(implicit M: Monoid[AA]): \/[AA, B]

def finalize(): Unit

def flatMap[AA >: A, D](g: (B) ⇒ \/[AA, D]): \/[AA, D]

def fold[X](l: (A) ⇒ X, r: (B) ⇒ X): X

def foldRight[Z](z: ⇒ Z)(f: (B, ⇒ Z) ⇒ Z): Z

def forall[BB >: B](p: (BB) ⇒ Boolean): Boolean

def foreach(g: (B) ⇒ Unit): Unit

final def getClass(): Class[_]

def getOrElse[BB >: B](x: ⇒ BB): BB

def hashCode(): Int

final def isInstanceOf[T0]: Boolean

def isLeft: Boolean

def isRight: Boolean

def leftMap[C](f: (A) ⇒ C): \/[C, B]

def loopl[AA >: A, BB >: B, X](left: (AA) ⇒ \/[X, \/[AA, BB]], right: (BB) ⇒ X): X

def loopr[AA >: A, BB >: B, X](left: (AA) ⇒ X, right: (BB) ⇒ \/[X, \/[AA, BB]]): X

def map[D](g: (B) ⇒ D): \/[A, D]

def merge[AA >: A](implicit ev: <~<[B, AA]): AA

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

def orElse[C, BB >: B](x: ⇒ \/[C, BB]): \/[C, BB]

def productIterator: Iterator[Any]

def productPrefix: String

def recover[BB >: B](pf: PartialFunction[A, BB]): \/[A, BB]

def recoverWith[AA >: A, BB >: B](pf: PartialFunction[AA, \/[AA, BB]]): \/[AA, BB]

def show[AA >: A, BB >: B](implicit SA: Show[AA], SB: Show[BB]): Cord

def swap: \/[B, A]

def swapped[AA, BB](k: (\/[B, A]) ⇒ \/[BB, AA]): \/[AA, BB]

final def synchronized[T0](arg0: ⇒ T0): T0

def toEither: Either[A, B]

def toList: List[B]

def toMaybe[BB >: B]: Maybe[BB]

def toOption: Option[B]

def toStream: Stream[B]

def toString(): String

def toThese: \&/[A, B]

def traverse[F[_], AA >: A, D](g: (B) ⇒ F[D])(implicit arg0: Applicative[F]): F[\/[AA, D]]

def unary_~: \/[B, A]

def validation: Validation[A, B]

def validationNel[AA >: A]: ValidationNel[AA, B]

def validationed[AA, BB](k: (Validation[A, B]) ⇒ Validation[AA, BB]): \/[AA, BB]

def valueOr[BB >: B](x: (A) ⇒ BB): BB

final def wait(): Unit

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

final def wait(arg0: Long): Unit

def |[BB >: B](x: ⇒ BB): BB

def |||[C, BB >: B](x: ⇒ \/[C, BB]): \/[C, BB]

def ~[AA, BB](k: (\/[B, A]) ⇒ \/[BB, AA]): \/[AA, BB]

Inherited from Serializable

Inherited from Serializable

Inherited from Product

Inherited from Equals