Either

Companion object Either

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

Represents a value of one of two possible types (a disjoint union). An instance of Either is an instance of either scala.util.Left or scala.util.Right.

A common use of Either is as an alternative to scala.Option for dealing with possibly missing values. In this usage, scala.None is replaced with a scala.util.Left which can contain useful information. scala.util.Right takes the place of scala.Some. Convention dictates that Left is used for failure and Right is used for success.

For example, you could use Either[String, Int] to indicate whether a received input is a String or an Int.

import scala.io.StdIn._
val in = readLine("Type Either a string or an Int: ")
val result: Either[String,Int] =
  try Right(in.toInt)
  catch {
    case e: NumberFormatException => Left(in)
  }

result match {
  case Right(x) => s"You passed me the Int: $x, which I will increment. $x + 1 = ${x+1}"
  case Left(x)  => s"You passed me the String: $x"
}

Either is right-biased, which means that Right is assumed to be the default case to operate on. If it is Left, operations like map and flatMap return the Left value unchanged:

def doubled(i: Int) = i * 2
Right(42).map(doubled) // Right(84)
Left(42).map(doubled)  // Left(42)

Since Either defines the methods map and flatMap, it can also be used in for comprehensions:

val right1 = Right(1)   : Right[Double, Int]
val right2 = Right(2)
val right3 = Right(3)
val left23 = Left(23.0) : Left[Double, Int]
val left42 = Left(42.0)

for {
  x <- right1
  y <- right2
  z <- right3
} yield x + y + z // Right(6)

for {
  x <- right1
  y <- right2
  z <- left23
} yield x + y + z // Left(23.0)

for {
  x <- right1
  y <- left23
  z <- right2
} yield x + y + z // Left(23.0)

// Guard expressions are not supported:
for {
  i <- right1
  if i > 0
} yield i
// error: value withFilter is not a member of Right[Double,Int]

// Similarly, refutable patterns are not supported:
for (x: Int <- right1) yield x
// error: value withFilter is not a member of Right[Double,Int]

// To use a filtered value, convert to an Option first,
// which drops the Left case, as None contains no value:
for {
  i <- right1.toOption
  if i > 0
} yield i

Since for comprehensions use map and flatMap, the types of function parameters used in the expression must be inferred. These types are constrained by the Either values. In particular, because of right-biasing, Left values may require an explicit type argument for type parameter B, the right value. Otherwise, it might be inferred as Nothing.

for {
  x <- left23
  y <- right1
  z <- left42  // type at this position: Either[Double, Nothing]
} yield x + y + z
//            ^
// error: ambiguous reference to overloaded definition,
// both method + in class Int of type (x: Char)Int
// and  method + in class Int of type (x: Byte)Int
// match argument types (Nothing)

for (x <- right2 ; y <- left23) yield x + y  // Left(23.0)
for (x <- right2 ; y <- left42) yield x + y  // error

for {
  x <- right1
  y <- left42  // type at this position: Either[Double, Nothing]
  z <- left23
} yield x + y + z
// Left(42.0), but unexpectedly a `Either[Double,String]`

Source: Either.scala

Linear Supertypes

java.io.Serializable, Product, Equals, AnyRef, Any

Known Subclasses

Left, Right

Type Hierarchy

Ordering

Alphabetic
By Inheritance

Inherited

Either
Serializable
Product
Equals
AnyRef
Any

Implicitly

by MergeableEither
by any2stringadd
by StringFormat
by Ensuring
by ArrowAssoc

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Visibility

Public
Protected

Abstract Value Members

abstract def canEqual(that: Any): Boolean
Checks whether this instance can possibly equal that.
Checks whether this instance can possibly equal that.
A method that should be called from every well-designed equals method that is open to be overridden in a subclass. See Programming in Scala, Chapter 28 for discussion and design.
that
the value being probed for possible equality
returns
true if this instance can possibly equal that, otherwise false
Definition Classes
Equals
abstract 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
```
abstract 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
```
abstract def productArity: Int
The size of this product.
The size of this product.
returns
for a product A(x₁, ..., x_k), returns k
Definition Classes
Product
abstract def productElement(n: Int): Any
The n^th element of this product, 0-based.
The n^th element of this product, 0-based. In other words, for a product A(x₁, ..., x_k), returns x_(n+1) where 0 <= n < k.
n
the index of the element to return
returns
the element n elements after the first element
Definition Classes
Product
Exceptions thrown
IndexOutOfBoundsException if the n is out of range(n < 0 || n >= productArity).

Concrete Value Members

final def !=(arg0: Any): Boolean
Test two objects for inequality.
Test two objects for inequality.
returns
true if !(this == that), false otherwise.
Definition Classes
AnyRef → Any
final def ##: Int
Equivalent to x.hashCode except for boxed numeric types and null.
Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.
returns
a hash value consistent with ==
Definition Classes
AnyRef → Any
def +(other: String): String
Implicit
This member is added by an implicit conversion from Either[A, B] toany2stringadd[Either[A, B]] performed by method any2stringadd in scala.Predef.
Definition Classes
any2stringadd
def ->[B](y: B): (Either[A, B], B)
Implicit
This member is added by an implicit conversion from Either[A, B] toArrowAssoc[Either[A, B]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc
Annotations
@inline()
final def ==(arg0: Any): Boolean
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
returns
true if the receiver object is equivalent to the argument; false otherwise.
Definition Classes
AnyRef → Any
final def asInstanceOf[T0]: T0
Forces the compiler to treat the receiver object as having type T0, even though doing so may violate type safety.
Forces the compiler to treat the receiver object as having type T0, even though doing so may violate type safety.
This method is useful when you believe you have type information the compiler doesn't, and it also isn't possible to check the type at runtime. In such situations, skipping type safety is the only option.
It is platform dependent whether asInstanceOf has any effect at runtime. It might do a runtime type test on the erasure of T0, insert a conversion (such as boxing/unboxing), fill in a default value, or do nothing at all.
In particular, asInstanceOf is not a type test. It does **not** mean:
```
this match {
 case x: T0 => x
 case _     => throw ClassCastException("...")
```
Use pattern matching or isInstanceOf for type testing instead.
Situations where asInstanceOf is useful:
- when flow analysis fails to deduce T0 automatically
- when down-casting a type parameter or an abstract type member (which cannot be checked at runtime due to type erasure) If there is any doubt and you are able to type test instead, you should do so.
Be careful of using asInstanceOf when T0 is a primitive type. When T0 is primitive, asInstanceOf may insert a conversion instead of a type test. If your intent is to convert, use a toT method (x.toChar, x.toByte, etc.).
returns
the receiver object.
Definition Classes
Any
Exceptions thrown
ClassCastException if the receiver is not an instance of the erasure of T0, if that can be checked on this platform
def clone(): AnyRef
Create a copy of the receiver object.
Create a copy of the receiver object.
The default implementation of the clone method is platform dependent.
returns
a copy of the receiver object.
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.CloneNotSupportedException]) @native()
Note
not specified by SLS as a member of AnyRef

final def contains[B1 >: B](elem: B1): Boolean

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"

elem: the element to test.
returns: true if this is a Right value equal to elem.

def ensuring(cond: (Either[A, B]) => Boolean, msg: => Any): Either[A, B]
Implicit
This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: (Either[A, B]) => Boolean): Either[A, B]
Implicit
This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean, msg: => Any): Either[A, B]
Implicit
This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean): Either[A, B]
Implicit
This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
final def eq(arg0: AnyRef): Boolean
Tests whether the argument (that) is a reference to the receiver object (this).
Tests whether the argument (that) is a reference to the receiver object (this).
The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional properties:
- It is consistent: for any non-null instances x and y of type AnyRef, multiple invocations of x.eq(y) consistently returns true or consistently returns false.
- For any non-null instance x of type AnyRef, x.eq(null) and null.eq(x) returns false.
- null.eq(null) returns true.
When overriding the equals or hashCode methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).
returns
true if the argument is a reference to the receiver object; false otherwise.
Definition Classes
AnyRef
def equals(arg0: AnyRef): Boolean
The equality method for reference types.
The equality method for reference types. Default implementation delegates to eq.
See also equals in scala.Any.
returns
true if the receiver object is equivalent to the argument; false otherwise.
Definition Classes
AnyRef → Any
def exists(p: (B) => Boolean): Boolean
Returns false if Left or returns the result of the application of the given predicate to the Right value.
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
```
def filterOrElse[A1 >: A](p: (B) => Boolean, zero: => A1): Either[A1, B]
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.
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)
```
def finalize(): Unit
Called by the garbage collector on the receiver object when there are no more references to the object.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.Throwable])
Note
not specified by SLS as a member of AnyRef
def flatMap[A1 >: A, B1](f: (B) => Either[A1, B1]): Either[A1, B1]
Binds the given function across Right.
Binds the given function across Right.
f
The function to bind across Right.

def flatten[A1 >: A, B1](implicit ev: <:<[B, Either[A1, B1]]): Either[A1, B1]

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)

def fold[C](fa: (A) => C, fb: (B) => C): C
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
Example:
1. val result = util.Try("42".toInt).toEither result.fold( e => s"Operation failed with $e", v => s"Operation produced value: $v" )
def forall(f: (B) => Boolean): Boolean
Returns true if Left or returns the result of the application of the given predicate to the Right value.
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
```
def foreach[U](f: (B) => U): Unit
Executes the given side-effecting function if this is a Right.
Executes the given side-effecting function if this is a Right.
```
Right(12).foreach(println) // prints "12"
Left(12).foreach(println)  // doesn't print
```
f
The side-effecting function to execute.
final def getClass(): Class[_ <: AnyRef]
Returns the runtime class representation of the object.
Returns the runtime class representation of the object.
returns
a class object corresponding to the runtime type of the receiver.
Definition Classes
AnyRef → Any
Annotations
@native()
def getOrElse[B1 >: B](or: => B1): B1
Returns the value from this Right or the given argument if this is a Left.
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
```
def hashCode(): Int
The hashCode method for reference types.
The hashCode method for reference types. See hashCode in scala.Any.
returns
the hash code value for this object.
Definition Classes
AnyRef → Any
Annotations
@native()
final def isInstanceOf[T0]: Boolean
Test whether the dynamic type of the receiver object has the same erasure as T0.
Test whether the dynamic type of the receiver object has the same erasure as T0.
Depending on what T0 is, the test is done in one of the below ways:
- T0 is a non-parameterized class type, e.g. BigDecimal: this method returns true if the value of the receiver object is a BigDecimal or a subtype of BigDecimal.
- T0 is a parameterized class type, e.g. List[Int]: this method returns true if the value of the receiver object is some List[X] for any X. For example, List(1, 2, 3).isInstanceOf[List[String]] will return true.
- T0 is some singleton type x.type or literal x: this method returns this.eq(x). For example, x.isInstanceOf[1] is equivalent to x.eq(1)
- T0 is an intersection X with Y or X & Y: this method is equivalent to x.isInstanceOf[X] && x.isInstanceOf[Y]
- T0 is a union X | Y: this method is equivalent to x.isInstanceOf[X] || x.isInstanceOf[Y]
- T0 is a type parameter or an abstract type member: this method is equivalent to isInstanceOf[U] where U is T0's upper bound, Any if T0 is unbounded. For example, x.isInstanceOf[A] where A is an unbounded type parameter will return true for any value of x.
This is exactly equivalent to the type pattern _: T0
returns
true if the receiver object is an instance of erasure of type T0; false otherwise.
Definition Classes
Any
Note
due to the unexpectedness of List(1, 2, 3).isInstanceOf[List[String]] returning true and x.isInstanceOf[A] where A is a type parameter or abstract member returning true, these forms issue a warning.
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.
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.
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

def left: LeftProjection[A, B]

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")

def map[B1](f: (B) => B1): Either[A, B1]
The given function is applied if this is a Right.
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)
```
def merge: B
Implicit
This member is added by an implicit conversion from Either[A, B] toMergeableEither[B] performed by method MergeableEither in scala.util.Either.This conversion will take place only if B is a superclass of A (B >: A).
Definition Classes
MergeableEither
final def ne(arg0: AnyRef): Boolean
Equivalent to !(this eq that).
Equivalent to !(this eq that).
returns
true if the argument is not a reference to the receiver object; false otherwise.
Definition Classes
AnyRef
final def notify(): Unit
Wakes up a single thread that is waiting on the receiver object's monitor.
Wakes up a single thread that is waiting on the receiver object's monitor.
Definition Classes
AnyRef
Annotations
@native()
Note
not specified by SLS as a member of AnyRef
final def notifyAll(): Unit
Wakes up all threads that are waiting on the receiver object's monitor.
Wakes up all threads that are waiting on the receiver object's monitor.
Definition Classes
AnyRef
Annotations
@native()
Note
not specified by SLS as a member of AnyRef
def orElse[A1 >: A, B1 >: B](or: => Either[A1, B1]): Either[A1, B1]
Returns this Right or the given argument if this is a Left.
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)
```
def productElementName(n: Int): String
The name of the n^th element of this product, 0-based.
The name of the n^th element of this product, 0-based. In the default implementation, an empty string.
n
the index of the element name to return
returns
the name of the specified element
Definition Classes
Product
Exceptions thrown
IndexOutOfBoundsException if the n is out of range(n < 0 || n >= productArity).
def productElementNames: Iterator[String]
An iterator over the names of all the elements of this product.
An iterator over the names of all the elements of this product.
Definition Classes
Product
def productIterator: Iterator[Any]
An iterator over all the elements of this product.
An iterator over all the elements of this product.
returns
in the default implementation, an Iterator[Any]
Definition Classes
Product
def productPrefix: String
A string used in the toString methods of derived classes.
A string used in the toString methods of derived classes. Implementations may override this method to prepend a string prefix to the result of toString methods.
returns
in the default implementation, the empty string
Definition Classes
Product

def swap: Either[B, A]

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

Examples:

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)

final def synchronized[T0](arg0: => T0): T0
Executes the code in body with an exclusive lock on this.
Executes the code in body with an exclusive lock on this.
returns
the result of body
Definition Classes
AnyRef
def toOption: Option[B]
Returns a Some containing the Right value if it exists or a None if this is a Left.
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
```
def toSeq: collection.immutable.Seq[B]
Returns a Seq containing the Right value if it exists or an empty Seq if this is a Left.
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()
```
def toString(): String
Creates a String representation of this object.
Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.
returns
a String representation of the object.
Definition Classes
AnyRef → Any
def toTry(implicit ev: <:<[A, Throwable]): Try[B]
final def wait(): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
Note
not specified by SLS as a member of AnyRef
final def wait(arg0: Long, arg1: Int): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
Note
not specified by SLS as a member of AnyRef
final def wait(arg0: Long): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException]) @native()
Note
not specified by SLS as a member of AnyRef

Deprecated Value Members

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
This member is added by an implicit conversion from Either[A, B] toStringFormat[Either[A, B]] performed by method StringFormat in scala.Predef.
Definition Classes
StringFormat
Annotations
@deprecated @inline()
Deprecated
(Since version 2.12.16) Use formatString.format(value) instead of value.formatted(formatString), or use the f"" string interpolator. In Java 15 and later, formatted resolves to the new method in String which has reversed parameters.
def right: RightProjection[A, B]
Projects this Either as a Right.
Projects this Either as a Right.
Because Either is right-biased, this method is not normally needed.
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Either is now right-biased, use methods directly on Either
def →[B](y: B): (Either[A, B], B)
Implicit
This member is added by an implicit conversion from Either[A, B] toArrowAssoc[Either[A, B]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use -> instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.

Inherited from Product

Value Members

abstract def productArity: Int
The size of this product.
The size of this product.
returns
for a product A(x₁, ..., x_k), returns k
Definition Classes
Product
abstract def productElement(n: Int): Any
The n^th element of this product, 0-based.
The n^th element of this product, 0-based. In other words, for a product A(x₁, ..., x_k), returns x_(n+1) where 0 <= n < k.
n
the index of the element to return
returns
the element n elements after the first element
Definition Classes
Product
Exceptions thrown
IndexOutOfBoundsException if the n is out of range(n < 0 || n >= productArity).
def productElementName(n: Int): String
The name of the n^th element of this product, 0-based.
The name of the n^th element of this product, 0-based. In the default implementation, an empty string.
n
the index of the element name to return
returns
the name of the specified element
Definition Classes
Product
Exceptions thrown
IndexOutOfBoundsException if the n is out of range(n < 0 || n >= productArity).
def productElementNames: Iterator[String]
An iterator over the names of all the elements of this product.
An iterator over the names of all the elements of this product.
Definition Classes
Product
def productIterator: Iterator[Any]
An iterator over all the elements of this product.
An iterator over all the elements of this product.
returns
in the default implementation, an Iterator[Any]
Definition Classes
Product
def productPrefix: String
A string used in the toString methods of derived classes.
A string used in the toString methods of derived classes. Implementations may override this method to prepend a string prefix to the result of toString methods.
returns
in the default implementation, the empty string
Definition Classes
Product

Inherited from Equals

Value Members

abstract def canEqual(that: Any): Boolean
Checks whether this instance can possibly equal that.
Checks whether this instance can possibly equal that.
A method that should be called from every well-designed equals method that is open to be overridden in a subclass. See Programming in Scala, Chapter 28 for discussion and design.
that
the value being probed for possible equality
returns
true if this instance can possibly equal that, otherwise false
Definition Classes
Equals

Inherited from AnyRef

Value Members

final def !=(arg0: Any): Boolean
Test two objects for inequality.
Test two objects for inequality.
returns
true if !(this == that), false otherwise.
Definition Classes
AnyRef → Any
final def ##: Int
Equivalent to x.hashCode except for boxed numeric types and null.
Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.
returns
a hash value consistent with ==
Definition Classes
AnyRef → Any
final def ==(arg0: Any): Boolean
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
returns
true if the receiver object is equivalent to the argument; false otherwise.
Definition Classes
AnyRef → Any
def clone(): AnyRef
Create a copy of the receiver object.
Create a copy of the receiver object.
The default implementation of the clone method is platform dependent.
returns
a copy of the receiver object.
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.CloneNotSupportedException]) @native()
Note
not specified by SLS as a member of AnyRef
final def eq(arg0: AnyRef): Boolean
Tests whether the argument (that) is a reference to the receiver object (this).
Tests whether the argument (that) is a reference to the receiver object (this).
The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional properties:
- It is consistent: for any non-null instances x and y of type AnyRef, multiple invocations of x.eq(y) consistently returns true or consistently returns false.
- For any non-null instance x of type AnyRef, x.eq(null) and null.eq(x) returns false.
- null.eq(null) returns true.
When overriding the equals or hashCode methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).
returns
true if the argument is a reference to the receiver object; false otherwise.
Definition Classes
AnyRef
def equals(arg0: AnyRef): Boolean
The equality method for reference types.
The equality method for reference types. Default implementation delegates to eq.
See also equals in scala.Any.
returns
true if the receiver object is equivalent to the argument; false otherwise.
Definition Classes
AnyRef → Any
def finalize(): Unit
Called by the garbage collector on the receiver object when there are no more references to the object.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.Throwable])
Note
not specified by SLS as a member of AnyRef
final def getClass(): Class[_ <: AnyRef]
Returns the runtime class representation of the object.
Returns the runtime class representation of the object.
returns
a class object corresponding to the runtime type of the receiver.
Definition Classes
AnyRef → Any
Annotations
@native()
def hashCode(): Int
The hashCode method for reference types.
The hashCode method for reference types. See hashCode in scala.Any.
returns
the hash code value for this object.
Definition Classes
AnyRef → Any
Annotations
@native()
final def ne(arg0: AnyRef): Boolean
Equivalent to !(this eq that).
Equivalent to !(this eq that).
returns
true if the argument is not a reference to the receiver object; false otherwise.
Definition Classes
AnyRef
final def notify(): Unit
Wakes up a single thread that is waiting on the receiver object's monitor.
Wakes up a single thread that is waiting on the receiver object's monitor.
Definition Classes
AnyRef
Annotations
@native()
Note
not specified by SLS as a member of AnyRef
final def notifyAll(): Unit
Wakes up all threads that are waiting on the receiver object's monitor.
Wakes up all threads that are waiting on the receiver object's monitor.
Definition Classes
AnyRef
Annotations
@native()
Note
not specified by SLS as a member of AnyRef
final def synchronized[T0](arg0: => T0): T0
Executes the code in body with an exclusive lock on this.
Executes the code in body with an exclusive lock on this.
returns
the result of body
Definition Classes
AnyRef
def toString(): String
Creates a String representation of this object.
Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.
returns
a String representation of the object.
Definition Classes
AnyRef → Any
final def wait(): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
Note
not specified by SLS as a member of AnyRef
final def wait(arg0: Long, arg1: Int): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
Note
not specified by SLS as a member of AnyRef
final def wait(arg0: Long): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException]) @native()
Note
not specified by SLS as a member of AnyRef

Inherited from Any

Value Members

final def asInstanceOf[T0]: T0
Forces the compiler to treat the receiver object as having type T0, even though doing so may violate type safety.
Forces the compiler to treat the receiver object as having type T0, even though doing so may violate type safety.
This method is useful when you believe you have type information the compiler doesn't, and it also isn't possible to check the type at runtime. In such situations, skipping type safety is the only option.
It is platform dependent whether asInstanceOf has any effect at runtime. It might do a runtime type test on the erasure of T0, insert a conversion (such as boxing/unboxing), fill in a default value, or do nothing at all.
In particular, asInstanceOf is not a type test. It does **not** mean:
```
this match {
 case x: T0 => x
 case _     => throw ClassCastException("...")
```
Use pattern matching or isInstanceOf for type testing instead.
Situations where asInstanceOf is useful:
- when flow analysis fails to deduce T0 automatically
- when down-casting a type parameter or an abstract type member (which cannot be checked at runtime due to type erasure) If there is any doubt and you are able to type test instead, you should do so.
Be careful of using asInstanceOf when T0 is a primitive type. When T0 is primitive, asInstanceOf may insert a conversion instead of a type test. If your intent is to convert, use a toT method (x.toChar, x.toByte, etc.).
returns
the receiver object.
Definition Classes
Any
Exceptions thrown
ClassCastException if the receiver is not an instance of the erasure of T0, if that can be checked on this platform
final def isInstanceOf[T0]: Boolean
Test whether the dynamic type of the receiver object has the same erasure as T0.
Test whether the dynamic type of the receiver object has the same erasure as T0.
Depending on what T0 is, the test is done in one of the below ways:
- T0 is a non-parameterized class type, e.g. BigDecimal: this method returns true if the value of the receiver object is a BigDecimal or a subtype of BigDecimal.
- T0 is a parameterized class type, e.g. List[Int]: this method returns true if the value of the receiver object is some List[X] for any X. For example, List(1, 2, 3).isInstanceOf[List[String]] will return true.
- T0 is some singleton type x.type or literal x: this method returns this.eq(x). For example, x.isInstanceOf[1] is equivalent to x.eq(1)
- T0 is an intersection X with Y or X & Y: this method is equivalent to x.isInstanceOf[X] && x.isInstanceOf[Y]
- T0 is a union X | Y: this method is equivalent to x.isInstanceOf[X] || x.isInstanceOf[Y]
- T0 is a type parameter or an abstract type member: this method is equivalent to isInstanceOf[U] where U is T0's upper bound, Any if T0 is unbounded. For example, x.isInstanceOf[A] where A is an unbounded type parameter will return true for any value of x.
This is exactly equivalent to the type pattern _: T0
returns
true if the receiver object is an instance of erasure of type T0; false otherwise.
Definition Classes
Any
Note
due to the unexpectedness of List(1, 2, 3).isInstanceOf[List[String]] returning true and x.isInstanceOf[A] where A is a type parameter or abstract member returning true, these forms issue a warning.

Inherited by implicit conversion MergeableEither fromEither[A, B] to MergeableEither[B]

Value Members

def merge: B
Implicit
This member is added by an implicit conversion from Either[A, B] toMergeableEither[B] performed by method MergeableEither in scala.util.Either.This conversion will take place only if B is a superclass of A (B >: A).
Definition Classes
MergeableEither

Inherited by implicit conversion any2stringadd fromEither[A, B] to any2stringadd[Either[A, B]]

Value Members

def +(other: String): String
Implicit
This member is added by an implicit conversion from Either[A, B] toany2stringadd[Either[A, B]] performed by method any2stringadd in scala.Predef.
Definition Classes
any2stringadd

Inherited by implicit conversion StringFormat fromEither[A, B] to StringFormat[Either[A, B]]

Value Members

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
This member is added by an implicit conversion from Either[A, B] toStringFormat[Either[A, B]] performed by method StringFormat in scala.Predef.
Definition Classes
StringFormat
Annotations
@deprecated @inline()
Deprecated
(Since version 2.12.16) Use formatString.format(value) instead of value.formatted(formatString), or use the f"" string interpolator. In Java 15 and later, formatted resolves to the new method in String which has reversed parameters.

Inherited by implicit conversion Ensuring fromEither[A, B] to Ensuring[Either[A, B]]

Value Members

def ensuring(cond: (Either[A, B]) => Boolean, msg: => Any): Either[A, B]
Implicit
This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: (Either[A, B]) => Boolean): Either[A, B]
Implicit
This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean, msg: => Any): Either[A, B]
Implicit
This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean): Either[A, B]
Implicit
This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

Inherited by implicit conversion ArrowAssoc fromEither[A, B] to ArrowAssoc[Either[A, B]]

Value Members

def ->[B](y: B): (Either[A, B], B)
Implicit
This member is added by an implicit conversion from Either[A, B] toArrowAssoc[Either[A, B]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc
Annotations
@inline()
def →[B](y: B): (Either[A, B], B)
Implicit
This member is added by an implicit conversion from Either[A, B] toArrowAssoc[Either[A, B]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use -> instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.

Ungrouped

abstract def canEqual(that: Any): Boolean
Checks whether this instance can possibly equal that.
Checks whether this instance can possibly equal that.
A method that should be called from every well-designed equals method that is open to be overridden in a subclass. See Programming in Scala, Chapter 28 for discussion and design.
that
the value being probed for possible equality
returns
true if this instance can possibly equal that, otherwise false
Definition Classes
Equals
abstract 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
```
abstract 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
```
abstract def productArity: Int
The size of this product.
The size of this product.
returns
for a product A(x₁, ..., x_k), returns k
Definition Classes
Product
abstract def productElement(n: Int): Any
The n^th element of this product, 0-based.
The n^th element of this product, 0-based. In other words, for a product A(x₁, ..., x_k), returns x_(n+1) where 0 <= n < k.
n
the index of the element to return
returns
the element n elements after the first element
Definition Classes
Product
Exceptions thrown
IndexOutOfBoundsException if the n is out of range(n < 0 || n >= productArity).
final def !=(arg0: Any): Boolean
Test two objects for inequality.
Test two objects for inequality.
returns
true if !(this == that), false otherwise.
Definition Classes
AnyRef → Any
final def ##: Int
Equivalent to x.hashCode except for boxed numeric types and null.
Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.
returns
a hash value consistent with ==
Definition Classes
AnyRef → Any
def +(other: String): String
Implicit
This member is added by an implicit conversion from Either[A, B] toany2stringadd[Either[A, B]] performed by method any2stringadd in scala.Predef.
Definition Classes
any2stringadd
def ->[B](y: B): (Either[A, B], B)
Implicit
This member is added by an implicit conversion from Either[A, B] toArrowAssoc[Either[A, B]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc
Annotations
@inline()
final def ==(arg0: Any): Boolean
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
returns
true if the receiver object is equivalent to the argument; false otherwise.
Definition Classes
AnyRef → Any
final def asInstanceOf[T0]: T0
Forces the compiler to treat the receiver object as having type T0, even though doing so may violate type safety.
Forces the compiler to treat the receiver object as having type T0, even though doing so may violate type safety.
This method is useful when you believe you have type information the compiler doesn't, and it also isn't possible to check the type at runtime. In such situations, skipping type safety is the only option.
It is platform dependent whether asInstanceOf has any effect at runtime. It might do a runtime type test on the erasure of T0, insert a conversion (such as boxing/unboxing), fill in a default value, or do nothing at all.
In particular, asInstanceOf is not a type test. It does **not** mean:
```
this match {
 case x: T0 => x
 case _     => throw ClassCastException("...")
```
Use pattern matching or isInstanceOf for type testing instead.
Situations where asInstanceOf is useful:
- when flow analysis fails to deduce T0 automatically
- when down-casting a type parameter or an abstract type member (which cannot be checked at runtime due to type erasure) If there is any doubt and you are able to type test instead, you should do so.
Be careful of using asInstanceOf when T0 is a primitive type. When T0 is primitive, asInstanceOf may insert a conversion instead of a type test. If your intent is to convert, use a toT method (x.toChar, x.toByte, etc.).
returns
the receiver object.
Definition Classes
Any
Exceptions thrown
ClassCastException if the receiver is not an instance of the erasure of T0, if that can be checked on this platform
def clone(): AnyRef
Create a copy of the receiver object.
Create a copy of the receiver object.
The default implementation of the clone method is platform dependent.
returns
a copy of the receiver object.
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.CloneNotSupportedException]) @native()
Note
not specified by SLS as a member of AnyRef

final def contains[B1 >: B](elem: B1): Boolean

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"

elem: the element to test.
returns: true if this is a Right value equal to elem.

def ensuring(cond: (Either[A, B]) => Boolean, msg: => Any): Either[A, B]
Implicit
This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: (Either[A, B]) => Boolean): Either[A, B]
Implicit
This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean, msg: => Any): Either[A, B]
Implicit
This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean): Either[A, B]
Implicit
This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
final def eq(arg0: AnyRef): Boolean
Tests whether the argument (that) is a reference to the receiver object (this).
Tests whether the argument (that) is a reference to the receiver object (this).
The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional properties:
- It is consistent: for any non-null instances x and y of type AnyRef, multiple invocations of x.eq(y) consistently returns true or consistently returns false.
- For any non-null instance x of type AnyRef, x.eq(null) and null.eq(x) returns false.
- null.eq(null) returns true.
When overriding the equals or hashCode methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).
returns
true if the argument is a reference to the receiver object; false otherwise.
Definition Classes
AnyRef
def equals(arg0: AnyRef): Boolean
The equality method for reference types.
The equality method for reference types. Default implementation delegates to eq.
See also equals in scala.Any.
returns
true if the receiver object is equivalent to the argument; false otherwise.
Definition Classes
AnyRef → Any
def exists(p: (B) => Boolean): Boolean
Returns false if Left or returns the result of the application of the given predicate to the Right value.
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
```
def filterOrElse[A1 >: A](p: (B) => Boolean, zero: => A1): Either[A1, B]
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.
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)
```
def finalize(): Unit
Called by the garbage collector on the receiver object when there are no more references to the object.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.Throwable])
Note
not specified by SLS as a member of AnyRef
def flatMap[A1 >: A, B1](f: (B) => Either[A1, B1]): Either[A1, B1]
Binds the given function across Right.
Binds the given function across Right.
f
The function to bind across Right.

def flatten[A1 >: A, B1](implicit ev: <:<[B, Either[A1, B1]]): Either[A1, B1]

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)

def fold[C](fa: (A) => C, fb: (B) => C): C
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
Example:
1. val result = util.Try("42".toInt).toEither result.fold( e => s"Operation failed with $e", v => s"Operation produced value: $v" )
def forall(f: (B) => Boolean): Boolean
Returns true if Left or returns the result of the application of the given predicate to the Right value.
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
```
def foreach[U](f: (B) => U): Unit
Executes the given side-effecting function if this is a Right.
Executes the given side-effecting function if this is a Right.
```
Right(12).foreach(println) // prints "12"
Left(12).foreach(println)  // doesn't print
```
f
The side-effecting function to execute.
final def getClass(): Class[_ <: AnyRef]
Returns the runtime class representation of the object.
Returns the runtime class representation of the object.
returns
a class object corresponding to the runtime type of the receiver.
Definition Classes
AnyRef → Any
Annotations
@native()
def getOrElse[B1 >: B](or: => B1): B1
Returns the value from this Right or the given argument if this is a Left.
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
```
def hashCode(): Int
The hashCode method for reference types.
The hashCode method for reference types. See hashCode in scala.Any.
returns
the hash code value for this object.
Definition Classes
AnyRef → Any
Annotations
@native()
final def isInstanceOf[T0]: Boolean
Test whether the dynamic type of the receiver object has the same erasure as T0.
Test whether the dynamic type of the receiver object has the same erasure as T0.
Depending on what T0 is, the test is done in one of the below ways:
- T0 is a non-parameterized class type, e.g. BigDecimal: this method returns true if the value of the receiver object is a BigDecimal or a subtype of BigDecimal.
- T0 is a parameterized class type, e.g. List[Int]: this method returns true if the value of the receiver object is some List[X] for any X. For example, List(1, 2, 3).isInstanceOf[List[String]] will return true.
- T0 is some singleton type x.type or literal x: this method returns this.eq(x). For example, x.isInstanceOf[1] is equivalent to x.eq(1)
- T0 is an intersection X with Y or X & Y: this method is equivalent to x.isInstanceOf[X] && x.isInstanceOf[Y]
- T0 is a union X | Y: this method is equivalent to x.isInstanceOf[X] || x.isInstanceOf[Y]
- T0 is a type parameter or an abstract type member: this method is equivalent to isInstanceOf[U] where U is T0's upper bound, Any if T0 is unbounded. For example, x.isInstanceOf[A] where A is an unbounded type parameter will return true for any value of x.
This is exactly equivalent to the type pattern _: T0
returns
true if the receiver object is an instance of erasure of type T0; false otherwise.
Definition Classes
Any
Note
due to the unexpectedness of List(1, 2, 3).isInstanceOf[List[String]] returning true and x.isInstanceOf[A] where A is a type parameter or abstract member returning true, these forms issue a warning.
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.
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.
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

def left: LeftProjection[A, B]

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")

def map[B1](f: (B) => B1): Either[A, B1]
The given function is applied if this is a Right.
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)
```
def merge: B
Implicit
This member is added by an implicit conversion from Either[A, B] toMergeableEither[B] performed by method MergeableEither in scala.util.Either.This conversion will take place only if B is a superclass of A (B >: A).
Definition Classes
MergeableEither
final def ne(arg0: AnyRef): Boolean
Equivalent to !(this eq that).
Equivalent to !(this eq that).
returns
true if the argument is not a reference to the receiver object; false otherwise.
Definition Classes
AnyRef
final def notify(): Unit
Wakes up a single thread that is waiting on the receiver object's monitor.
Wakes up a single thread that is waiting on the receiver object's monitor.
Definition Classes
AnyRef
Annotations
@native()
Note
not specified by SLS as a member of AnyRef
final def notifyAll(): Unit
Wakes up all threads that are waiting on the receiver object's monitor.
Wakes up all threads that are waiting on the receiver object's monitor.
Definition Classes
AnyRef
Annotations
@native()
Note
not specified by SLS as a member of AnyRef
def orElse[A1 >: A, B1 >: B](or: => Either[A1, B1]): Either[A1, B1]
Returns this Right or the given argument if this is a Left.
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)
```
def productElementName(n: Int): String
The name of the n^th element of this product, 0-based.
The name of the n^th element of this product, 0-based. In the default implementation, an empty string.
n
the index of the element name to return
returns
the name of the specified element
Definition Classes
Product
Exceptions thrown
IndexOutOfBoundsException if the n is out of range(n < 0 || n >= productArity).
def productElementNames: Iterator[String]
An iterator over the names of all the elements of this product.
An iterator over the names of all the elements of this product.
Definition Classes
Product
def productIterator: Iterator[Any]
An iterator over all the elements of this product.
An iterator over all the elements of this product.
returns
in the default implementation, an Iterator[Any]
Definition Classes
Product
def productPrefix: String
A string used in the toString methods of derived classes.
A string used in the toString methods of derived classes. Implementations may override this method to prepend a string prefix to the result of toString methods.
returns
in the default implementation, the empty string
Definition Classes
Product

def swap: Either[B, A]

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

Examples:

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)

final def synchronized[T0](arg0: => T0): T0
Executes the code in body with an exclusive lock on this.
Executes the code in body with an exclusive lock on this.
returns
the result of body
Definition Classes
AnyRef
def toOption: Option[B]
Returns a Some containing the Right value if it exists or a None if this is a Left.
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
```
def toSeq: collection.immutable.Seq[B]
Returns a Seq containing the Right value if it exists or an empty Seq if this is a Left.
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()
```
def toString(): String
Creates a String representation of this object.
Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.
returns
a String representation of the object.
Definition Classes
AnyRef → Any
def toTry(implicit ev: <:<[A, Throwable]): Try[B]
final def wait(): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
Note
not specified by SLS as a member of AnyRef
final def wait(arg0: Long, arg1: Int): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
Note
not specified by SLS as a member of AnyRef
final def wait(arg0: Long): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException]) @native()
Note
not specified by SLS as a member of AnyRef
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
This member is added by an implicit conversion from Either[A, B] toStringFormat[Either[A, B]] performed by method StringFormat in scala.Predef.
Definition Classes
StringFormat
Annotations
@deprecated @inline()
Deprecated
(Since version 2.12.16) Use formatString.format(value) instead of value.formatted(formatString), or use the f"" string interpolator. In Java 15 and later, formatted resolves to the new method in String which has reversed parameters.
def right: RightProjection[A, B]
Projects this Either as a Right.
Projects this Either as a Right.
Because Either is right-biased, this method is not normally needed.
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Either is now right-biased, use methods directly on Either
def →[B](y: B): (Either[A, B], B)
Implicit
This member is added by an implicit conversion from Either[A, B] toArrowAssoc[Either[A, B]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use -> instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.

Packages

Package structure

Automatic imports

Either

Companion object Either

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

Abstract Value Members

Concrete Value Members

Deprecated Value Members

Inherited from Product

Value Members

Inherited from Equals

Value Members

Inherited from AnyRef

Value Members

Inherited from Any

Value Members

Inherited by implicit conversion MergeableEither fromEither[A, B] to MergeableEither[B]

Value Members

Inherited by implicit conversion any2stringadd fromEither[A, B] to any2stringadd[Either[A, B]]

Value Members

Inherited by implicit conversion StringFormat fromEither[A, B] to StringFormat[Either[A, B]]

Value Members

Inherited by implicit conversion Ensuring fromEither[A, B] to Ensuring[Either[A, B]]

Value Members

Inherited by implicit conversion ArrowAssoc fromEither[A, B] to ArrowAssoc[Either[A, B]]

Value Members

Ungrouped

Packages

Package structure

Automatic imports

Either

Companion object Either

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

Abstract Value Members

Concrete Value Members

Deprecated Value Members

Inherited from Product

Value Members

Inherited from Equals

Value Members

Inherited from AnyRef

Value Members

Inherited from Any

Value Members

Inherited by implicit conversion MergeableEither fromEither[A, B] to MergeableEither[B]

Value Members

Inherited by implicit conversion any2stringadd fromEither[A, B] to any2stringadd[Either[A, B]]

Value Members

Inherited by implicit conversion StringFormat fromEither[A, B] to StringFormat[Either[A, B]]

Value Members

Inherited by implicit conversion Ensuring fromEither[A, B] to Ensuring[Either[A, B]]

Value Members

Inherited by implicit conversion ArrowAssoc fromEither[A, B] to ArrowAssoc[Either[A, B]]

Value Members

Ungrouped

Either