Left
The left side of the disjoint union, as opposed to thescala.util.Right side.
Attributes
- Source
- Either.scala
- Graph
- Supertypes
Members list
Value members
Concrete methods
Returnstrue if this is aLeft,false otherwise.
Returnstrue if this is aLeft,false otherwise.
Left("tulip").isLeft // trueRight("venus fly-trap").isLeft // falseAttributes
- Source
- Either.scala
Returnstrue if this is aRight,false otherwise.
Returnstrue if this is aRight,false otherwise.
Left("tulip").isRight // falseRight("venus fly-trap").isRight // trueAttributes
- Source
- Either.scala
Upcasts thisLeft[A, B] toEither[A, B1]
Upcasts thisLeft[A, B] toEither[A, B1]
Left(1) // Either[Int, Nothing]Left(1).withRight[String] // Either[Int, String]Attributes
- Source
- Either.scala
Inherited methods
Returnstrue if this is aRight and its value is equal toelem (as determined by==), returnsfalse otherwise.
Returnstrue if this is aRight and its value is equal toelem (as determined by==), returnsfalse 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 parameters
- elem
the element to test.
Attributes
- Returns
trueif this is aRightvalue equal toelem.- Inherited from:
- Either
- Source
- Either.scala
Returnsfalse ifLeft or returns the result of the application of the given predicate to theRight value.
Returnsfalse ifLeft or returns the result of the application of the given predicate to theRight value.
Right(12).exists(_ > 10) // trueRight(7).exists(_ > 10) // falseLeft(12).exists(_ => true) // falseAttributes
- Inherited from:
- Either
- Source
- Either.scala
ReturnsRight with the existing value ofRight if this is aRight and the given predicatep holds for the right value, orLeft(zero) if this is aRight and the given predicatep does not hold for the right value, orLeft with the existing value ofLeft if this is aLeft.
ReturnsRight with the existing value ofRight if this is aRight and the given predicatep holds for the right value, orLeft(zero) if this is aRight and the given predicatep does not hold for the right value, orLeft with the existing value ofLeft if this is aLeft.
Right(12).filterOrElse(_ > 10, -1) // Right(12)Right(7).filterOrElse(_ > 10, -1) // Left(-1)Left(7).filterOrElse(_ => false, -1) // Left(7)Attributes
- Inherited from:
- Either
- Source
- Either.scala
Binds the given function acrossRight.
Binds the given function acrossRight.
Value parameters
- f
The function to bind across
Right.
Attributes
- Inherited from:
- Either
- Source
- Either.scala
Returns the right value if this is right or this value if this is left
Returns the right value if this is right or this value if this is left
Attributes
- 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
Appliesfa if this is aLeft orfb if this is aRight.
Appliesfa if this is aLeft orfb if this is aRight.
Value parameters
- fa
the function to apply if this is a
Left- fb
the function to apply if this is a
Right
Attributes
- Returns
the results of applying the function
- Example
val result = util.Try("42".toInt).toEitherresult.fold( e => s"Operation failed with $e", v => s"Operation produced value: $v")- Inherited from:
- Either
- Source
- Either.scala
Returnstrue ifLeft or returns the result of the application of the given predicate to theRight value.
Returnstrue ifLeft or returns the result of the application of the given predicate to theRight value.
Right(12).forall(_ > 10) // trueRight(7).forall(_ > 10) // falseLeft(12).forall(_ => false) // trueAttributes
- Inherited from:
- Either
- Source
- Either.scala
Executes the given side-effecting function if this is aRight.
Executes the given side-effecting function if this is aRight.
Right(12).foreach(println) // prints "12"Left(12).foreach(println) // doesn't printValue parameters
- f
The side-effecting function to execute.
Attributes
- Inherited from:
- Either
- Source
- Either.scala
Returns the value from thisRight or the given argument if this is aLeft.
Returns the value from thisRight or the given argument if this is aLeft.
Right(12).getOrElse(17) // 12Left(12).getOrElse(17) // 17Attributes
- Inherited from:
- Either
- Source
- Either.scala
Joins anEither throughLeft.
Joins anEither throughLeft.
This method requires that the left side of thisEither is itself anEither 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 aLeft[Either[C, B]] then the containedEither[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, andjoinRight, are analogous toOption#flatten.
Attributes
- Inherited from:
- Either
- Source
- Either.scala
Joins anEither throughRight.
Joins anEither throughRight.
This method requires that the right side of thisEither is itself anEither 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 aRight[Either[A, C]] then the containedEither[A, C] will be returned, otherwise this value will be returned unmodified.
Attributes
- 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 toOption#flatten- Inherited from:
- Either
- Source
- Either.scala
Projects thisEither as aLeft.
Projects thisEither as aLeft.
This allows for-comprehensions over the left side ofEither instances, reversingEither's usual right-bias.
For example
for (s <- Left("flower").left) yield s.length // Left(6)Continuing the analogy withscala.Option, aLeftProjection declares thatLeft should be analogous toSome in some code.
// using Optiondef interactWithDB(x: Query): Option[Result] = try Some(getResultFromDatabase(x)) catch { case _: SQLException => None }// this will only be executed if interactWithDB returns a Someval 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 Eitherdef 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")Attributes
- Inherited from:
- Either
- Source
- Either.scala
The given function is applied if this is aRight.
The given function is applied if this is aRight.
Right(12).map(x => "flower") // Result: Right("flower")Left(12).map(x => "flower") // Result: Left(12)Attributes
- Inherited from:
- Either
- Source
- Either.scala
Returns thisRight or the given argument if this is aLeft.
Returns thisRight or the given argument if this is aLeft.
Right(1) orElse Left(2) // Right(1)Left(1) orElse Left(2) // Left(2)Left(1) orElse Left(2) orElse Right(3) // Right(3)Attributes
- Inherited from:
- Either
- Source
- Either.scala
An iterator over the names of all the elements of this product.
An iterator over the names of all the elements of this product.
Attributes
- Inherited from:
- Product
- Source
- Product.scala
An iterator over all the elements of this product.
An iterator over all the elements of this product.
Attributes
- Returns
in the default implementation, an
Iterator[Any]- Inherited from:
- Product
- Source
- Product.scala
If this is aLeft, then return the left value inRight or vice versa.
If this is aLeft, then return the left value inRight or vice versa.
Attributes
- 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 aSome containing theRight value if it exists or aNone if this is aLeft.
Returns aSome containing theRight value if it exists or aNone if this is aLeft.
Right(12).toOption // Some(12)Left(12).toOption // NoneAttributes
- Inherited from:
- Either
- Source
- Either.scala
Returns aSeq containing theRight value if it exists or an emptySeq if this is aLeft.
Returns aSeq containing theRight value if it exists or an emptySeq if this is aLeft.
Right(12).toSeq // Seq(12)Left(12).toSeq // Seq()Attributes
- Inherited from:
- Either
- Source
- Either.scala
Deprecated and Inherited methods
Projects thisEither as aRight.
Projects thisEither as aRight.
BecauseEither is right-biased, this method is not normally needed.
Attributes
- Deprecated
[Since version 2.13.0]Either is now right-biased, use methods directly on Either- Inherited from:
- Either
- Source
- Either.scala