Right

final case class Right[+A, +B](value: B) extends Either[A, B]

The right side of the disjoint union, as opposed to the scala.util.Left side.

Source: Either.scala

class Either[A, B]

trait Serializable

trait Product

trait Equals

class Object

trait Matchable

class Any

Value members

Concrete methods

Source: Either.scala

Source: Either.scala

Upcasts this Right[A, B] to Either[A1, B]

Right("x")               // Either[Nothing, String]
Right("x").withLeft[Int] // Either[Int, String]

Source: Either.scala

Inherited methods

Returns true if this is a Right and its value is equal to elem (as determined by ==), returns false otherwise.

// Returns true because value of Right is "something" which equals "something".
Right("something") contains "something"

// Returns false because value of Right is "something" which does not equal "anything".
Right("something") contains "anything"

// Returns false because it's not a Right value.
Left("something") contains "something"

Value Params

elem: the element to test.

Returns

true if this is a Right value equal to elem.

Inherited from

Either

Source

Either.scala

Returns false if Left or returns the result of the application of the given predicate to the Right value.

Right(12).exists(_ > 10)   // true
Right(7).exists(_ > 10)    // false
Left(12).exists(_ => true) // false

Inherited from: Either
Source: Either.scala

Returns Right with the existing value of Right if this is a Right and the given predicate p holds for the right value, or Left(zero) if this is a Right and the given predicate p does not hold for the right value, or Left with the existing value of Left if this is a Left.

Right(12).filterOrElse(_ > 10, -1)   // Right(12)
Right(7).filterOrElse(_ > 10, -1)    // Left(-1)
Left(7).filterOrElse(_ => false, -1) // Left(7)

Inherited from: Either
Source: Either.scala

Binds the given function across Right.

Value Params

f: The function to bind across Right.

Inherited from

Either

Source

Either.scala

Returns the right value if this is right or this value if this is left

Example: val l: Either[String, Either[String, Int]] = Left("pancake") val rl: Either[String, Either[String, Int]] = Right(Left("flounder")) val rr: Either[String, Either[String, Int]] = Right(Right(7)) l.flatten //Either[String, Int]: Left("pancake") rl.flatten //Either[String, Int]: Left("flounder") rr.flatten //Either[String, Int]: Right(7)
Equivalent to flatMap(id => id)
Inherited from: Either
Source: Either.scala

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

Value Params

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

Example

val result = util.Try("42".toInt).toEither
result.fold(
  e => s"Operation failed with $e",
  v => s"Operation produced value: $v"
)

Inherited from

Either

Source

Either.scala

Returns true if Left or returns the result of the application of the given predicate to the Right value.

Right(12).forall(_ > 10)    // true
Right(7).forall(_ > 10)     // false
Left(12).forall(_ => false) // true

Inherited from: Either
Source: Either.scala

Executes the given side-effecting function if this is a Right.

Right(12).foreach(println) // prints "12"
Left(12).foreach(println)  // doesn't print

Value Params

f: The side-effecting function to execute.

Inherited from

Either

Source

Either.scala

Returns the value from this Right or the given argument if this is a Left.

Right(12).getOrElse(17) // 12
Left(12).getOrElse(17)  // 17

Inherited from: Either
Source: Either.scala

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.

Inherited from: Either
Source: Either.scala

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.

Example: 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
Inherited from: Either
Source: Either.scala

Projects this Either as a Left.

This allows for-comprehensions over the left side of Either instances, reversing Either's usual right-bias.

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 _: SQLException => None
  }

// this will only be executed if interactWithDB returns a Some
val report = for (result <- interactWithDB(someQuery)) yield generateReport(result)
report match {
  case Some(r) => send(r)
  case None    => log("report not generated, not sure why...")
}

// using Either
def interactWithDB(x: Query): Either[Exception, Result] =
  try Right(getResultFromDatabase(x))
  catch {
    case e: SQLException => Left(e)
  }

 // run a report only if interactWithDB returns a Right
 val report = for (result <- interactWithDB(someQuery)) yield generateReport(result)
 report match {
   case Right(r) => send(r)
   case Left(e)  => log(s"report not generated, reason was $e")
 }
 // only report errors
 for (e <- interactWithDB(someQuery).left) log(s"query failed, reason was $e")

Inherited from: Either
Source: Either.scala

The given function is applied if this is a Right.

Right(12).map(x => "flower") // Result: Right("flower")
Left(12).map(x => "flower")  // Result: Left(12)

Inherited from: Either
Source: Either.scala

Returns this Right or the given argument if this is a Left.

Right(1) orElse Left(2) // Right(1)
Left(1) orElse Left(2)  // Left(2)
Left(1) orElse Left(2) orElse Right(3) // Right(3)

Inherited from: Either
Source: Either.scala

An iterator over the names of all the elements of this product.

Inherited from: Product
Source: Product.scala

An iterator over all the elements of this product.

Returns: in the default implementation, an Iterator[Any]
Inherited from: Product
Source: Product.scala

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

Example: val left: Either[String, Int] = Left("left") val right: Either[Int, String] = left.swap // Result: Right("left")
val right = Right(2) val left = Left(3) for { r1 <- right r2 <- left.swap } yield r1 * r2 // Right(6)
Inherited from: Either
Source: Either.scala

Returns a Some containing the Right value if it exists or a None if this is a Left.

Right(12).toOption // Some(12)
Left(12).toOption  // None

Inherited from: Either
Source: Either.scala

Returns a Seq containing the Right value if it exists or an empty Seq if this is a Left.

Right(12).toSeq // Seq(12)
Left(12).toSeq  // Seq()

Inherited from: Either
Source: Either.scala

Inherited from: Either
Source: Either.scala

Deprecated and Inherited methods

@deprecated("Either is now right-biased, use methods directly on Either", "2.13.0")

Projects this Either as a Right.

Because Either is right-biased, this method is not normally needed.

Deprecated
Inherited from: Either
Source: Either.scala