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
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
Test two objects for inequality.
Test two objects for inequality.
true if !(this == that), false otherwise.
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.
a hash value consistent with ==
Test two objects for equality.
Test two objects for equality.
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
true if the receiver object is equivalent to the argument; false otherwise.
Cast the receiver object to be of type T0.
Cast the receiver object to be of type T0.
Note that the success of a cast at runtime is modulo Scala's erasure semantics.
Therefore the expression 1.asInstanceOf[String] will throw a ClassCastException at
runtime, while the expression List(1).asInstanceOf[List[String]] will not.
In the latter example, because the type argument is erased as part of compilation it is
not possible to check whether the contents of the list are of the requested type.
the receiver object.
if the receiver object is not an instance of the erasure of type T0.
Create a copy of the receiver object.
Tests whether the argument (arg0) is a reference to the receiver object (this).
Tests whether the argument (arg0) 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:
x and y of type AnyRef, multiple invocations of
x.eq(y) consistently returns true or consistently returns false.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).
true if the argument is a reference to the receiver object; false otherwise.
The equality method for reference types.
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.
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.
the function to apply if this is a Left
the function to apply if this is a Right
the results of applying the function
val result: Either[Exception, Value] = possiblyFailingOperation() log(result.fold( ex => "Operation failed with " + ex, v => "Operation produced value: " + v ))
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).
A representation that corresponds to the dynamic class of the receiver object.
A representation that corresponds to the dynamic class of the receiver object.
The nature of the representation is platform dependent.
a representation that corresponds to the dynamic class of the receiver object.
not specified by SLS as a member of AnyRef
The hashCode method for reference types.
Test whether the dynamic type of the receiver object is T0.
Test whether the dynamic type of the receiver object is T0.
Note that the result of the test is modulo Scala's erasure semantics.
Therefore the expression 1.isInstanceOf[String] will return false, while the
expression List(1).isInstanceOf[List[String]] will return true.
In the latter example, because the type argument is erased as part of compilation it is
not possible to check whether the contents of the list are of the specified type.
true if the receiver object is an instance of erasure of type T0; false otherwise.
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
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.
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
Projects this Either as a Left.
Equivalent to !(this eq that).
Equivalent to !(this eq that).
true if the argument is not a reference to the receiver object; false otherwise.
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.
not specified by SLS as a member of AnyRef
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.
not specified by SLS as a member of AnyRef
Projects this Either as a Right.
If this is a Left, then return the left value in Right or vice versa.
If this is a Left, then return the left value in Right or vice versa.
val l: Either[String, Int] = Left("left") val r: Either[Int, String] = l.swap // Result: Right("left")
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.
a String representation of the object.
(either: StringAdd).self
(either: StringFormat).self
(either: ArrowAssoc[Either[A, B]]).x
(Since version 2.10.0) Use leftOfArrow instead
(either: Ensuring[Either[A, B]]).x
(Since version 2.10.0) Use resultOfEnsuring instead
Represents a value of one of two possible types (a disjoint union.) Instances of Either are either an instance of scala.util.Left or scala.util.Right.
A common use of Either is as an alternative to scala.Option for dealing with possible 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]A projection can be used to selectively operate on a value of type Either, depending on whether it is of type Left or Right. For example, to transform an Either using a function, in the case where it's a Left, one can first apply the
leftprojection and invokemapon that projected Either. If arightprojection is applied to that Left, the original Left is returned, unmodified.Like with other types which define a
mapmethod, the same can be achieved using a for-comprehension:To support multiple projections as generators in for-comprehensions, the Either type also defines a
flatMapmethod.1.0, 11/10/2008
2.7