sealed abstract class \/[A, B] extends Product with Serializable
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 for all Scala versions, 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 in Scala versions <2.12. 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
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Type Members
- final class SwitchingDisjunction[X] extends AnyRef
Abstract Value Members
Concrete Value Members
- final def !=(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
- final def ##: Int
- Definition Classes
- AnyRef → Any
- def +++(x: => \/[A, B])(implicit M1: Semigroup[B], M2: Semigroup[A]): \/[A, B]
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[C](f: => \/[A, (B) => C]): \/[A, 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[lang]
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.CloneNotSupportedException]) @native()
- 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(onLeft: => A)(f: (B) => Boolean): \/[A, 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: AnyRef): Boolean
- Definition Classes
- AnyRef → Any
- def exists[BB >: B](p: (BB) => Boolean): Boolean
Return
trueif this disjunction is a right value satisfying the given predicate. - def filter(p: (B) => Boolean)(implicit M: Monoid[A]): \/[A, B]
Filter on the right of this disjunction.
- def finalize(): Unit
- Attributes
- protected[lang]
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.Throwable])
- def flatMap[D](g: (B) => \/[A, D]): \/[A, 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 foldConst[X](l: => X, r: => X): X
Evaluate
land return if left, otherwise,r. - 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
trueif 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[_ <: AnyRef]
- Definition Classes
- AnyRef → Any
- Annotations
- @native()
- 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
- Annotations
- @native()
- final def isInstanceOf[T0]: Boolean
- Definition Classes
- Any
- def isLeft: Boolean
Return
trueif this disjunction is left. - def isRight: Boolean
Return
trueif this disjunction is right. - def leftMap[C](f: (A) => C): \/[C, B]
Run the given function on the left value.
- def loopl[X](left: (A) => \/[X, \/[A, B]], right: (B) => X): X
Spin in tail-position on the left value of this disjunction.
- def loopr[X](left: (A) => X, right: (B) => \/[X, \/[A, B]]): 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
- Annotations
- @native()
- final def notifyAll(): Unit
- Definition Classes
- AnyRef
- Annotations
- @native()
- def orElse[C](x: => \/[C, B]): \/[C, B]
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 orRaiseError[F[_]](implicit F: MonadError[F, A]): F[B]
- def productElementName(n: Int): String
- Definition Classes
- Product
- def productElementNames: Iterator[String]
- Definition Classes
- Product
- def productIterator: Iterator[Any]
- Definition Classes
- Product
- def productPrefix: String
- Definition Classes
- Product
- def recover(pf: PartialFunction[A, B]): \/[A, B]
Run the given function on the left and return right with the result.
- def recoverWith(pf: PartialFunction[A, \/[A, B]]): \/[A, B]
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.Eitherat your own peril. - def toIList[BB >: B]: IList[BB]
Return an empty list or list with one element on the right of this disjunction.
- def toLazyList: LazyList[B]
Return an empty LazyList or stream with one element on the right of this disjunction.
- 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 toString(): String
- Definition Classes
- AnyRef → Any
- def toThese: \&/[A, B]
Convert to a These.
- def toValidation: Validation[A, B]
Convert to a Validation.
- def toValidationNel[AA >: A]: ValidationNel[AA, B]
Convert to a ValidationNel.
- def traverse[F[_], D](g: (B) => F[D])(implicit arg0: Applicative[F]): F[\/[A, 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 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(classOf[java.lang.InterruptedException])
- final def wait(arg0: Long, arg1: Int): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.InterruptedException])
- final def wait(arg0: Long): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.InterruptedException]) @native()
- 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](x: => \/[C, B]): \/[C, B]
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