Scala 3
3.3.1
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Scala 3/scala

scala

package scala

Core Scala types. They are always available without an explicit import.

Attributes

Members list

Packages

package scala.annotation
package scala.beans
package scala.collection
package scala.compat
package scala.compiletime
package scala.concurrent

This package object contains primitives for concurrent and parallel programming.

This package object contains primitives for concurrent and parallel programming.

Guide

A more detailed guide to Futures and Promises, including discussion and examples can be found at https://docs.scala-lang.org/overviews/core/futures.html.

Common Imports

When working with Futures, you will often find that importing the whole concurrent package is convenient:

import scala.concurrent._

When using things like Futures, it is often required to have an implicit ExecutionContext in scope. The general advice for these implicits are as follows.

If the code in question is a class or method definition, and no ExecutionContext is available, request one from the caller by adding an implicit parameter list:

def myMethod(myParam: MyType)(implicit ec: ExecutionContext) = …
//Or
class MyClass(myParam: MyType)(implicit ec: ExecutionContext) { … }

This allows the caller of the method, or creator of the instance of the class, to decide which ExecutionContext should be used.

For typical REPL usage and experimentation, importing the global ExecutionContext is often desired.

import scala.concurrent.ExcutionContext.Implicits.global

Specifying Durations

Operations often require a duration to be specified. A duration DSL is available to make defining these easier:

import scala.concurrent.duration._
val d: Duration = 10.seconds

Using Futures For Non-blocking Computation

Basic use of futures is easy with the factory method on Future, which executes a provided function asynchronously, handing you back a future result of that function without blocking the current thread. In order to create the Future you will need either an implicit or explicit ExecutionContext to be provided:

import scala.concurrent._
import ExecutionContext.Implicits.global  // implicit execution context

val firstZebra: Future[Int] = Future {
 val words = Files.readAllLines("/etc/dictionaries-common/words").asScala
 words.indexOfSlice("zebra")
}

Avoid Blocking

Although blocking is possible in order to await results (with a mandatory timeout duration):

import scala.concurrent.duration._
Await.result(firstZebra, 10.seconds)

and although this is sometimes necessary to do, in particular for testing purposes, blocking in general is discouraged when working with Futures and concurrency in order to avoid potential deadlocks and improve performance. Instead, use callbacks or combinators to remain in the future domain:

val animalRange: Future[Int] = for {
 aardvark <- firstAardvark
 zebra <- firstZebra
} yield zebra - aardvark

animalRange.onSuccess {
 case x if x > 500000 => println("It's a long way from Aardvark to Zebra")
}

Attributes

package scala.deriving
package scala.io
package scala.jdk

The jdk package contains utilities to interact with JDK classes.

The jdk package contains utilities to interact with JDK classes.

This packages offers a number of converters, that are able to wrap or copy types from the scala library to equivalent types in the JDK class library and vice versa:

- CollectionConverters, converting collections like scala.collection.Seq, scala.collection.Map, scala.collection.Set, scala.collection.mutable.Buffer, scala.collection.Iterator and scala.collection.Iterable to their JDK counterparts - OptionConverters, converting between Option and java.util.Optional and primitive variations - StreamConverters, to create JDK Streams from scala collections - DurationConverters, for conversions between scala scala.concurrent.duration.FiniteDuration and java.time.Duration - FunctionConverters, from scala Functions to java java.util.function.Function, java.util.function.UnaryOperator, java.util.function.Consumer and java.util.function.Predicate, as well as primitive variations and Bi-variations.

By convention, converters that wrap an object to provide a different interface to the same underlying data structure use .asScala and .asJava extension methods, whereas converters that copy the underlying data structure use .toScala and .toJava.

In the javaapi package, the same converters can be found with a java-friendly interface that don't rely on implicit enrichments.

Additionally, this package offers Accumulators, capable of efficiently traversing JDK Streams.

Attributes

package scala.math

The package object scala.math contains methods for performing basic numeric operations such as elementary exponential, logarithmic, root and trigonometric functions.

The package object scala.math contains methods for performing basic numeric operations such as elementary exponential, logarithmic, root and trigonometric functions.

All methods forward to java.lang.Math unless otherwise noted.

Attributes

See also
package scala.quoted
package scala.ref
package scala.reflect
package scala.runtime
package scala.sys

The package object scala.sys contains methods for reading and altering core aspects of the virtual machine as well as the world outside of it.

The package object scala.sys contains methods for reading and altering core aspects of the virtual machine as well as the world outside of it.

Attributes

package scala.util

Type members

Classlikes

object #::

Attributes

Source
package.scala
Supertypes
class Object
trait Matchable
class Any
Self type
#::.type
sealed abstract class *:[+H, +T <: Tuple] extends NonEmptyTuple

Attributes

Companion
object
Source
Tuple.scala
Supertypes
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
object *:

Attributes

Companion
class
Source
Tuple.scala
Supertypes
trait Sum
trait Mirror
class Object
trait Matchable
class Any
Self type
*:.type
sealed abstract class <:<[-From, +To] extends From => To, Serializable

An instance of A <:< B witnesses that A is a subtype of B.

An instance of A <:< B witnesses that A is a subtype of B. Requiring an implicit argument of the type A <:< B encodes the generalized constraint A <: B.

To constrain any abstract type T that's in scope in a method's argument list (not just the method's own type parameters) simply add an implicit argument of type T <:< U, where U is the required upper bound; or for lower-bounds, use: L <:< T, where L is the required lower bound.

In case of any confusion over which method goes in what direction, all the "Co" methods (including apply) go from left to right in the type ("with" the type), and all the "Contra" methods go from right to left ("against" the type). E.g., apply turns a From into a To, and substituteContra replaces the Tos in a type with Froms.

In part contributed by Jason Zaugg.

Type parameters

From

a type which is proved a subtype of To

To

a type which is proved a supertype of From

Attributes

See also

=:= for expressing equality constraints

Example

scala.Option#flatten

sealed trait Option[+A] {
  // def flatten[B, A <: Option[B]]: Option[B] = ...
  // won't work, since the A in flatten shadows the class-scoped A.
  def flatten[B](implicit ev: A <:< Option[B]): Option[B]
    = if(isEmpty) None else ev(get)
  // Because (A <:< Option[B]) <: (A => Option[B]), ev can be called to turn the
  // A from get into an Option[B], and because ev is implicit, that call can be
  // left out and inserted automatically.
}
Companion
object
Source
typeConstraints.scala
Supertypes
trait Serializable
trait From => To
class Object
trait Matchable
class Any
Known subtypes
class From =:= To
object <:<

Attributes

Companion
class
Source
typeConstraints.scala
Supertypes
class Object
trait Matchable
class Any
Self type
<:<.type
sealed abstract class =:=[From, To] extends From <:< To, Serializable

An instance of A =:= B witnesses that the types A and B are equal.

An instance of A =:= B witnesses that the types A and B are equal. It also acts as a A <:< B, but not a B <:< A (directly) due to restrictions on subclassing.

In case of any confusion over which method goes in what direction, all the "Co" methods (including apply) go from left to right in the type ("with" the type), and all the "Contra" methods go from right to left ("against" the type). E.g., apply turns a From into a To, and substituteContra replaces the Tos in a type with Froms.

Type parameters

From

a type which is proved equal to To

To

a type which is proved equal to From

Attributes

See also

<:< for expressing subtyping constraints

Example

An in-place variant of scala.collection.mutable.ArrayBuffer#transpose 

implicit class BufOps[A](private val buf: ArrayBuffer[A]) extends AnyVal {
  def inPlaceTranspose[E]()(implicit ev: A =:= ArrayBuffer[E]) = ???
  // Because ArrayBuffer is invariant, we can't make do with just a A <:< ArrayBuffer[E]
  // Getting buffers *out* from buf would work, but adding them back *in* wouldn't.
}
Source
typeConstraints.scala
Supertypes
class From <:< To
trait Serializable
trait From => To
class Object
trait Matchable
class Any
Show all
abstract open class Any

Class Any is the root of the Scala class hierarchy.

Class Any is the root of the Scala class hierarchy. Every class in a Scala execution environment inherits directly or indirectly from this class.

Starting with Scala 2.10 it is possible to directly extend Any using universal traits. A universal trait is a trait that extends Any, only has defs as members, and does no initialization.

The main use case for universal traits is to allow basic inheritance of methods for value classes. For example,

trait Printable extends Any {
  def print(): Unit = println(this)
}
class Wrapper(val underlying: Int) extends AnyVal with Printable

val w = new Wrapper(3)
w.print()

See the Value Classes and Universal Traits for more details on the interplay of universal traits and value classes.

Attributes

final abstract class AnyKind

The super-type of all types.

Attributes

class AnyRef

Class AnyRef is the root class of all reference types.

Class AnyRef is the root class of all reference types. All types except the value types descend from this class.

Attributes

Known subtypes
trait () => R
class FromJavaSupplier[T]
trait Reference[T]
trait ReferenceWrapper[T]
class PhantomReference[T]
class SoftReference[T]
class WeakReference[T]
trait T1 => R
trait SetOps[A, CC, C]
trait SetOps[A, CC, C]
trait Set[A]
class AbstractSet[A]
class BitSet
class BitSet1
class BitSet2
class BitSetN
class HashSet[A]
class ListSet[A]
class Set1[A]
class Set2[A]
class Set3[A]
class Set4[A]
class TreeSet[A]
class ValueSet
trait SortedSet[A]
trait SortedSetOps[A, CC, C]
trait StrictOptimizedSortedSetOps[A, CC, C]
trait StrictOptimizedSetOps[A, CC, C]
trait SetOps[A, CC, C]
class HashSet[A]
class LinkedHashSet[A]
trait Set[A]
class AbstractSet[A]
class BitSet
class TreeSet[A]
trait SortedSet[A]
trait SortedSetOps[A, CC, C]
trait Set[A]
class AbstractSet[A]
trait SortedSet[A]
trait BitSet
trait SortedSetOps[A, CC, C]
trait BitSetOps[C]
trait SortedSetFactoryDefaults[A, CC, WithFilterCC]
trait StrictOptimizedSortedSetOps[A, CC, C]
trait StrictOptimizedSetOps[A, CC, C]
class FromJavaConsumer[T]
class FromJavaFunction[T, R]
class AbstractFunction1[T1, R]
class From <:< To
class From =:= To
class Conversion[T, U]
trait PartialFunction[A, B]
trait MapOps[K, V, CC, C]
trait MapOps[K, V, CC, C]
trait Map[K, V]
class AbstractMap[K, V]
class HashMap[K, V]
class IntMap[T]
class ListMap[K, V]
class LongMap[T]
class Map1[K, V]
class Map2[K, V]
class Map3[K, V]
class Map4[K, V]
class WithDefault[K, V]
class WithDefault[K, V]
class TreeMap[K, V]
class TreeSeqMap[K, V]
class VectorMap[K, V]
trait SeqMap[K, V]
trait SortedMap[K, V]
trait SortedMapOps[K, V, CC, C]
trait StrictOptimizedSortedMapOps[K, V, CC, C]
trait StrictOptimizedMapOps[K, V, CC, C]
trait MapOps[K, V, CC, C]
class TrieMap[K, V]
class AnyRefMap[K, V]
class CollisionProofHashMap[K, V]
class HashMap[K, V]
class LinkedHashMap[K, V]
class ListMap[K, V]
class LongMap[V]
trait Map[K, V]
trait Map[K, V]
class AbstractMap[K, V]
class WithDefault[K, V]
class WithDefault[K, V]
class OpenHashMap[Key, Value]
class TreeMap[K, V]
trait MultiMap[K, V]
trait SeqMap[K, V]
trait SortedMap[K, V]
trait SortedMapOps[K, V, CC, C]
trait Map[K, V]
class AbstractMap[K, V]
trait DefaultMap[K, V]
trait SeqMap[K, V]
trait SortedMap[K, V]
trait MapFactoryDefaults[K, V, CC, WithFilterCC]
class WeakHashMap[K, V]
trait MapView[K, V]
class AbstractMapView[K, V]
class Filter[K, V]
class FilterKeys[K, V]
class Id[K, V]
class MapValues[K, V, W]
class TapEach[K, V, U]
trait SortedMapFactoryDefaults[K, V, CC, WithFilterCC, UnsortedCC]
trait SortedMapOps[K, V, CC, C]
trait StrictOptimizedSortedMapOps[K, V, CC, C]
trait StrictOptimizedMapOps[K, V, CC, C]
trait Seq[A]
trait Seq[A]
class AbstractSeq[A]
class ArraySeq[A]
class ofBoolean
class ofByte
class ofChar
class ofDouble
class ofFloat
class ofInt
class ofLong
class ofRef[T]
class ofShort
class ofUnit
class LazyList[A]
class List[A]
class ::[A]
object Nil
class NumericRange[T]
class Exclusive[T]
class Inclusive[T]
class Queue[A]
class Range
class Exclusive
class Inclusive
class Stream[A]
class Cons[A]
object Empty
class Vector[A]
trait IndexedSeq[A]
trait LinearSeq[A]
trait Seq[A]
class AbstractSeq[A]
class AbstractBuffer[A]
class ArrayBuffer[A]
class ArrayDeque[A]
class Queue[A]
class Stack[A]
class ListBuffer[A]
class UnrolledBuffer[T]
class ArraySeq[T]
class ofBoolean
class ofByte
class ofChar
class ofDouble
class ofFloat
class ofInt
class ofLong
class ofRef[T]
class ofShort
class ofUnit
trait Buffer[A]
trait IndexedBuffer[A]
trait IndexedSeq[T]
class Accumulator[A, CC, C]
class AnyAccumulator[A]
class AbstractSeq[A]
trait IndexedSeq[A]
trait LinearSeq[A]
trait (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10) => R
class AbstractFunction10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, R]
trait (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11) => R
class AbstractFunction11[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, R]
trait (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12) => R
class AbstractFunction12[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, R]
trait (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13) => R
class AbstractFunction13[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, R]
trait (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14) => R
class AbstractFunction14[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, R]
trait (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15) => R
class AbstractFunction15[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, R]
trait (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16) => R
class AbstractFunction16[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, R]
trait (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17) => R
class AbstractFunction17[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, R]
trait (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18) => R
class AbstractFunction18[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, R]
trait (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19) => R
class AbstractFunction19[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, R]
trait (T1, T2) => R
class FromJavaBiConsumer[T, U]
class FromJavaBiFunction[T, U, R]
class FromJavaBiPredicate[T, U]
class AbstractFunction2[T1, T2, R]
trait (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20) => R
class AbstractFunction20[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, R]
trait (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21) => R
class AbstractFunction21[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, R]
trait (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22) => R
class AbstractFunction22[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22, R]
trait (T1, T2, T3) => R
class AbstractFunction3[T1, T2, T3, R]
trait (T1, T2, T3, T4) => R
class AbstractFunction4[T1, T2, T3, T4, R]
trait (T1, T2, T3, T4, T5) => R
class AbstractFunction5[T1, T2, T3, T4, T5, R]
trait (T1, T2, T3, T4, T5, T6) => R
class AbstractFunction6[T1, T2, T3, T4, T5, T6, R]
trait (T1, T2, T3, T4, T5, T6, T7) => R
class AbstractFunction7[T1, T2, T3, T4, T5, T6, T7, R]
trait (T1, T2, T3, T4, T5, T6, T7, T8) => R
class AbstractFunction8[T1, T2, T3, T4, T5, T6, T7, T8, R]
trait (T1, T2, T3, T4, T5, T6, T7, T8, T9) => R
class AbstractFunction9[T1, T2, T3, T4, T5, T6, T7, T8, T9, R]
Show all
abstract open class AnyVal

AnyVal is the root class of all value types, which describe values not implemented as objects in the underlying host system.

AnyVal is the root class of all value types, which describe values not implemented as objects in the underlying host system. Value classes are specified in Scala Language Specification, section 12.2.

The standard implementation includes nine AnyVal subtypes:

scala.Double, scala.Float, scala.Long, scala.Int, scala.Char, scala.Short, and scala.Byte are the numeric value types.

scala.Unit and scala.Boolean are the non-numeric value types.

Other groupings:

Prior to Scala 2.10, AnyVal was a sealed trait. Beginning with Scala 2.10, however, it is possible to define a subclass of AnyVal called a user-defined value class which is treated specially by the compiler. Properly-defined user value classes provide a way to improve performance on user-defined types by avoiding object allocation at runtime, and by replacing virtual method invocations with static method invocations.

User-defined value classes which avoid object allocation...

  • must have a single val parameter that is the underlying runtime representation.

  • can define defs, but no vals, vars, or nested traitss, classes or objects.

  • typically extend no other trait apart from AnyVal.

  • cannot be used in type tests or pattern matching.

  • may not override equals or hashCode methods.

A minimal example:

class Wrapper(val underlying: Int) extends AnyVal {
  def foo: Wrapper = new Wrapper(underlying * 19)
}

It's important to note that user-defined value classes are limited, and in some circumstances, still must allocate a value class instance at runtime. These limitations and circumstances are explained in greater detail in the Value Classes and Universal Traits.

Attributes

Supertypes
trait Matchable
class Any
Known subtypes
class Deferrer[A]
class Partial[T, U]
class Deferrer[A]
class UnwrapOp
class ArrayOps[A]
class SearchImpl[Repr, A]
class Shape
class StringOps
class DoubleMult
class DurationInt
class DurationLong
class IntMult
class LongMult
class RichBiFunctionAsFunction2[T, U, R]
class RichFunction2AsBiFunction[T, U, R]
class FutureOps[T]
class RichOption[A]
class RichOptional[A]
class RichBoolean
class RichByte
class RichChar
class RichDouble
class RichFloat
class RichInt
class RichLong
class RichShort
class Tuple2Zipped[El1, It1, El2, It2]
class Ops[T1, T2]
class Tuple3Zipped[El1, It1, El2, It2, El3, It3]
class Ops[T1, T2, T3]
class ChainingOps[A]
class MergeableEither[A]
class Boolean
class Byte
class Char
class Double
class Float
class UnliftOps[A, B]
class Int
class Long
class ElementWiseExtractor[A, B]
class ArrowAssoc[A]
class Ensuring[A]
class StringFormat[A]
class any2stringadd[A]
class Short
class Unit
class ValueOf[T]
class Addr
class NameRef
Show all
trait App extends DelayedInit

The App trait can be used to quickly turn objects into executable programs.

The App trait can be used to quickly turn objects into executable programs. Here is an example:

object Main extends App {
  Console.println("Hello World: " + (args mkString ", "))
}

No explicit main method is needed. Instead, the whole class body becomes the “main method”.

args returns the current command line arguments as an array.

Caveats

It should be noted that this trait is implemented using the DelayedInit functionality, which means that fields of the object will not have been initialized before the main method has been executed.

Future versions of this trait will no longer extend DelayedInit.

In Scala 3, the DelayedInit feature was dropped. App exists only in a limited form that also does not support command line arguments and will be deprecated in the future.

@main methods are the recommended scheme to generate programs that can be invoked from the command line in Scala 3.

@main def runMyProgram(args: String*): Unit = {
  // your program here
}

If programs need to cross-build between Scala 2 and Scala 3, it is recommended to use an explicit main method:

object Main {
  def main(args: Array[String]): Unit = {
    // your program here
  }
}

Attributes

Source
App.scala
Supertypes
trait DelayedInit
class Object
trait Matchable
class Any
object Array

Utility methods for operating on arrays.

Utility methods for operating on arrays. For example:

val a = Array(1, 2)
val b = Array.ofDim[Int](2)
val c = Array.concat(a, b)

where the array objects a, b and c have respectively the values Array(1, 2), Array(0, 0) and Array(1, 2, 0, 0).

Attributes

Companion
class
Source
Array.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Array.type
final class Array[T](_length: Int) extends Serializable, Cloneable

Arrays are mutable, indexed collections of values.

Arrays are mutable, indexed collections of values. Array[T] is Scala's representation for Java's T[].

val numbers = Array(1, 2, 3, 4)
val first = numbers(0) // read the first element
numbers(3) = 100 // replace the 4th array element with 100
val biggerNumbers = numbers.map(_ * 2) // multiply all numbers by two

Arrays make use of two common pieces of Scala syntactic sugar, shown on lines 2 and 3 of the above example code. Line 2 is translated into a call to apply(Int), while line 3 is translated into a call to update(Int, T).

Two implicit conversions exist in scala.Predef that are frequently applied to arrays: a conversion to scala.collection.ArrayOps (shown on line 4 of the example above) and a conversion to scala.collection.mutable.ArraySeq (a subtype of scala.collection.Seq). Both types make available many of the standard operations found in the Scala collections API. The conversion to ArrayOps is temporary, as all operations defined on ArrayOps return an Array, while the conversion to ArraySeq is permanent as all operations return a ArraySeq.

The conversion to ArrayOps takes priority over the conversion to ArraySeq. For instance, consider the following code:

val arr = Array(1, 2, 3)
val arrReversed = arr.reverse
val seqReversed : collection.Seq[Int] = arr.reverse

Value arrReversed will be of type Array[Int], with an implicit conversion to ArrayOps occurring to perform the reverse operation. The value of seqReversed, on the other hand, will be computed by converting to ArraySeq first and invoking the variant of reverse that returns another ArraySeq.

Attributes

See also

Scala Language Specification, for in-depth information on the transformations the Scala compiler makes on Arrays (Sections 6.6 and 6.15 respectively.)

"Scala 2.8 Arrays" the Scala Improvement Document detailing arrays since Scala 2.8.

"The Scala 2.8 Collections' API" section on Array by Martin Odersky for more information.

Companion
object
Source
Array.scala
Supertypes
trait Cloneable
trait Serializable
class Object
trait Matchable
class Any
final abstract class Boolean extends AnyVal

Boolean (equivalent to Java's boolean primitive type) is a subtype of scala.AnyVal.

Boolean (equivalent to Java's boolean primitive type) is a subtype of scala.AnyVal. Instances of Boolean are not represented by an object in the underlying runtime system.

There is an implicit conversion from scala.Boolean => scala.runtime.RichBoolean which provides useful non-primitive operations.

Attributes

Companion
object
Source
Boolean.scala
Supertypes
class AnyVal
trait Matchable
class Any
object Boolean

Attributes

Companion
class
Source
Boolean.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Boolean.type
final abstract class Byte extends AnyVal

Byte, a 8-bit signed integer (equivalent to Java's byte primitive type) is a subtype of scala.AnyVal.

Byte, a 8-bit signed integer (equivalent to Java's byte primitive type) is a subtype of scala.AnyVal. Instances of Byte are not represented by an object in the underlying runtime system.

There is an implicit conversion from scala.Byte => scala.runtime.RichByte which provides useful non-primitive operations.

Attributes

Companion
object
Source
Byte.scala
Supertypes
class AnyVal
trait Matchable
class Any
object Byte

Attributes

Companion
class
Source
Byte.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Byte.type
sealed trait CanEqual[-L, -R]

A marker trait indicating that values of type L can be compared to values of type R.

A marker trait indicating that values of type L can be compared to values of type R.

Attributes

Companion
object
Source
CanEqual.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
object derived
object CanEqual

Companion object containing a few universally known CanEqual instances. CanEqual instances involving primitive types or the Null type are handled directly in the compiler (see Implicits.synthesizedCanEqual), so they are not included here.

Companion object containing a few universally known CanEqual instances. CanEqual instances involving primitive types or the Null type are handled directly in the compiler (see Implicits.synthesizedCanEqual), so they are not included here.

Attributes

Companion
trait
Source
CanEqual.scala
Supertypes
trait Sum
trait Mirror
class Object
trait Matchable
class Any
Self type
CanEqual.type
final abstract class Char extends AnyVal

Char, a 16-bit unsigned integer (equivalent to Java's char primitive type) is a subtype of scala.AnyVal.

Char, a 16-bit unsigned integer (equivalent to Java's char primitive type) is a subtype of scala.AnyVal. Instances of Char are not represented by an object in the underlying runtime system.

There is an implicit conversion from scala.Char => scala.runtime.RichChar which provides useful non-primitive operations.

Attributes

Companion
object
Source
Char.scala
Supertypes
class AnyVal
trait Matchable
class Any
object Char

Attributes

Companion
class
Source
Char.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Char.type
object Console extends AnsiColor

Implements functionality for printing Scala values on the terminal.

Implements functionality for printing Scala values on the terminal. For reading values use StdIn. Also defines constants for marking up text on ANSI terminals.

Console Output

Use the print methods to output text.

scala> Console.printf(
  "Today the outside temperature is a balmy %.1f°C. %<.1f°C beats the previous record of %.1f°C.\n",
  -137.0,
  -135.05)
Today the outside temperature is a balmy -137.0°C. -137.0°C beats the previous record of -135.1°C.

ANSI escape codes

Use the ANSI escape codes for colorizing console output either to STDOUT or STDERR.

import Console.{GREEN, RED, RESET, YELLOW_B, UNDERLINED}

object PrimeTest {

  def isPrime(): Unit = {

    val candidate = io.StdIn.readInt().ensuring(_ > 1)

    val prime = (2 to candidate - 1).forall(candidate % _ != 0)

    if (prime)
      Console.println(s"${RESET}${GREEN}yes${RESET}")
    else
      Console.err.println(s"${RESET}${YELLOW_B}${RED}${UNDERLINED}NO!${RESET}")
  }

  def main(args: Array[String]): Unit = isPrime()

}

$ scala PrimeTest
1234567891
yes
$ scala PrimeTest
56474
NO!

IO redefinition

Use IO redefinition to temporarily swap in a different set of input and/or output streams. In this example the stream based method above is wrapped into a function.

import java.io.{ByteArrayOutputStream, StringReader}

object FunctionalPrimeTest {

  def isPrime(candidate: Int): Boolean = {

    val input = new StringReader(s"$candidate\n")
    val outCapture = new ByteArrayOutputStream
    val errCapture = new ByteArrayOutputStream

    Console.withIn(input) {
      Console.withOut(outCapture) {
        Console.withErr(errCapture) {
          PrimeTest.isPrime()
        }
      }
    }

    if (outCapture.toByteArray.nonEmpty) // "yes"
      true
    else if (errCapture.toByteArray.nonEmpty) // "NO!"
      false
    else throw new IllegalArgumentException(candidate.toString)
  }

  def main(args: Array[String]): Unit = {
    val primes = (2 to 50) filter (isPrime)
    println(s"First primes: $primes")
  }

}

$ scala FunctionalPrimeTest
First primes: Vector(2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47)

Attributes

Source
Console.scala
Supertypes
trait AnsiColor
class Object
trait Matchable
class Any
Self type
Console.type
abstract class Conversion[-T, +U] extends T => U

A class for implicit values that can serve as implicit conversions. The implicit resolution algorithm will act as if there existed the additional implicit definition:

A class for implicit values that can serve as implicit conversions. The implicit resolution algorithm will act as if there existed the additional implicit definition:

def $implicitConversion[T, U](x: T)(c: Conversion[T, U]): U = c(x)

However, the presence of this definition would slow down implicit search since its outermost type matches any pair of types. Therefore, implicit search contains a special case in Implicits#discardForView which emulates the conversion in a more efficient way.

Note that this is a SAM class - function literals are automatically converted to the Conversion values.

Also note that in bootstrapped dotty, Predef.<:< should inherit from Conversion. This would cut the number of special cases in discardForView from two to one.

The Conversion class can also be used to convert explicitly, using the convert extension method.

Attributes

Source
Conversion.scala
Supertypes
trait T => U
class Object
trait Matchable
class Any
final abstract class Double extends AnyVal

Double, a 64-bit IEEE-754 floating point number (equivalent to Java's double primitive type) is a subtype of scala.AnyVal.

Double, a 64-bit IEEE-754 floating point number (equivalent to Java's double primitive type) is a subtype of scala.AnyVal. Instances of Double are not represented by an object in the underlying runtime system.

There is an implicit conversion from scala.Double => scala.runtime.RichDouble which provides useful non-primitive operations.

Attributes

Companion
object
Source
Double.scala
Supertypes
class AnyVal
trait Matchable
class Any
object Double

Attributes

Companion
class
Source
Double.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Double.type
final class DummyImplicit

A type for which there is always an implicit value.

A type for which there is always an implicit value.

Attributes

Companion
object
Source
DummyImplicit.scala
Supertypes
class Object
trait Matchable
class Any
object DummyImplicit

Attributes

Companion
class
Source
DummyImplicit.scala
Supertypes
class Object
trait Matchable
class Any
Self type
trait Dynamic

A marker trait that enables dynamic invocations.

A marker trait that enables dynamic invocations. Instances x of this trait allow method invocations x.meth(args) for arbitrary method names meth and argument lists args as well as field accesses x.field for arbitrary field names field.

If a call is not natively supported by x (i.e. if type checking fails), it is rewritten according to the following rules:

foo.method("blah")      ~~> foo.applyDynamic("method")("blah")
foo.method(x = "blah")  ~~> foo.applyDynamicNamed("method")(("x", "blah"))
foo.method(x = 1, 2)    ~~> foo.applyDynamicNamed("method")(("x", 1), ("", 2))
foo.field           ~~> foo.selectDynamic("field")
foo.varia = 10      ~~> foo.updateDynamic("varia")(10)
foo.arr(10) = 13    ~~> foo.selectDynamic("arr").update(10, 13)
foo.arr(10)         ~~> foo.applyDynamic("arr")(10)

As of Scala 2.10, defining direct or indirect subclasses of this trait is only possible if the language feature dynamics is enabled.

Attributes

Source
Dynamic.scala
Supertypes
class Any
case object EmptyTuple extends Tuple

A tuple of 0 elements.

A tuple of 0 elements.

Attributes

Source
Tuple.scala
Supertypes
trait Singleton
trait Product
trait Mirror
trait Serializable
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
Self type
EmptyTuple.type
abstract class Enumeration(initial: Int) extends Serializable

Defines a finite set of values specific to the enumeration.

Defines a finite set of values specific to the enumeration. Typically these values enumerate all possible forms something can take and provide a lightweight alternative to case classes.

Each call to a Value method adds a new unique value to the enumeration. To be accessible, these values are usually defined as val members of the enumeration.

All values in an enumeration share a common, unique type defined as the Value type member of the enumeration (Value selected on the stable identifier path of the enumeration instance).

Values SHOULD NOT be added to an enumeration after its construction; doing so makes the enumeration thread-unsafe. If values are added to an enumeration from multiple threads (in a non-synchronized fashion) after construction, the behavior of the enumeration is undefined.

Value parameters

initial

The initial value from which to count the integers that identifies values at run-time.

Attributes

Example 

// Define a new enumeration with a type alias and work with the full set of enumerated values
object WeekDay extends Enumeration {
 type WeekDay = Value
 val Mon, Tue, Wed, Thu, Fri, Sat, Sun = Value
}
import WeekDay._
def isWorkingDay(d: WeekDay) = ! (d == Sat || d == Sun)
WeekDay.values filter isWorkingDay foreach println
// output:
// Mon
// Tue
// Wed
// Thu
// Fri


// Example of adding attributes to an enumeration by extending the Enumeration.Val class
object Planet extends Enumeration {
 protected case class PlanetVal(mass: Double, radius: Double) extends super.Val {
   def surfaceGravity: Double = Planet.G * mass / (radius * radius)
   def surfaceWeight(otherMass: Double): Double = otherMass * surfaceGravity
 }
 import scala.language.implicitConversions
 implicit def valueToPlanetVal(x: Value): PlanetVal = x.asInstanceOf[PlanetVal]
 val G: Double = 6.67300E-11
 val Mercury = PlanetVal(3.303e+23, 2.4397e6)
 val Venus   = PlanetVal(4.869e+24, 6.0518e6)
 val Earth   = PlanetVal(5.976e+24, 6.37814e6)
 val Mars    = PlanetVal(6.421e+23, 3.3972e6)
 val Jupiter = PlanetVal(1.9e+27, 7.1492e7)
 val Saturn  = PlanetVal(5.688e+26, 6.0268e7)
 val Uranus  = PlanetVal(8.686e+25, 2.5559e7)
 val Neptune = PlanetVal(1.024e+26, 2.4746e7)
}
println(Planet.values.filter(_.radius > 7.0e6))
// output:
// Planet.ValueSet(Jupiter, Saturn, Uranus, Neptune)
Source
Enumeration.scala
Supertypes
trait Serializable
class Object
trait Matchable
class Any
Known subtypes
object RoundingMode
Self type
trait Equals

An interface containing operations for equality.

An interface containing operations for equality. The only method not already present in class AnyRef is canEqual.

Attributes

Source
Equals.scala
Supertypes
class Any
Known subtypes
trait Map[K, V]
trait Map[K, V]
class AbstractMap[K, V]
class HashMap[K, V]
class IntMap[T]
class ListMap[K, V]
class LongMap[T]
class Map1[K, V]
class Map2[K, V]
class Map3[K, V]
class Map4[K, V]
class WithDefault[K, V]
class WithDefault[K, V]
class TreeMap[K, V]
class TreeSeqMap[K, V]
class VectorMap[K, V]
trait SeqMap[K, V]
trait SortedMap[K, V]
trait Map[K, V]
trait Map[K, V]
class TrieMap[K, V]
class AbstractMap[K, V]
class AnyRefMap[K, V]
class CollisionProofHashMap[K, V]
class HashMap[K, V]
class LinkedHashMap[K, V]
class ListMap[K, V]
class LongMap[V]
class WithDefault[K, V]
class WithDefault[K, V]
class OpenHashMap[Key, Value]
class TreeMap[K, V]
trait MultiMap[K, V]
trait SeqMap[K, V]
trait SortedMap[K, V]
class AbstractMap[K, V]
trait DefaultMap[K, V]
trait SeqMap[K, V]
trait SortedMap[K, V]
trait Seq[A]
trait Seq[A]
class AbstractSeq[A]
class ArraySeq[A]
class ofBoolean
class ofByte
class ofChar
class ofDouble
class ofFloat
class ofInt
class ofLong
class ofRef[T]
class ofShort
class ofUnit
class LazyList[A]
class List[A]
class ::[A]
object Nil
class NumericRange[T]
class Exclusive[T]
class Inclusive[T]
class Queue[A]
class Range
class Exclusive
class Inclusive
class Stream[A]
class Cons[A]
object Empty
class Vector[A]
trait IndexedSeq[A]
trait LinearSeq[A]
trait Seq[A]
class AbstractSeq[A]
class AbstractBuffer[A]
class ArrayBuffer[A]
class ArrayDeque[A]
class Queue[A]
class Stack[A]
class ListBuffer[A]
class UnrolledBuffer[T]
class ArraySeq[T]
class ofBoolean
class ofByte
class ofChar
class ofDouble
class ofFloat
class ofInt
class ofLong
class ofRef[T]
class ofShort
class ofUnit
trait Buffer[A]
trait IndexedBuffer[A]
trait IndexedSeq[T]
class Accumulator[A, CC, C]
class AnyAccumulator[A]
class AbstractSeq[A]
trait IndexedSeq[A]
trait LinearSeq[A]
trait Set[A]
trait Set[A]
class AbstractSet[A]
class BitSet
class BitSet1
class BitSet2
class BitSetN
class HashSet[A]
class ListSet[A]
class Set1[A]
class Set2[A]
class Set3[A]
class Set4[A]
class TreeSet[A]
class ValueSet
trait SortedSet[A]
trait Set[A]
class AbstractSet[A]
class BitSet
class HashSet[A]
class LinkedHashSet[A]
class TreeSet[A]
trait SortedSet[A]
class AbstractSet[A]
trait SortedSet[A]
trait BitSet
class AnyValManifest[T]
trait ClassTag[T]
trait Manifest[T]
trait Product
trait Enum
trait EnumValue
class TupleXXL
class Either[A, B]
class Left[A, B]
class Right[A, B]
class Try[T]
class Failure[T]
class Success[T]
class Option[A]
object None
class Some[A]
trait Product1[T1]
class Tuple1[T1]
trait Product10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10)
trait Product11[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11)
trait Product12[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12)
trait Product13[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13)
trait Product14[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14)
trait Product15[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15)
trait Product16[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16)
trait Product17[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17)
trait Product18[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18)
trait Product19[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19)
trait Product2[T1, T2]
class (T1, T2)
trait Product20[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20)
trait Product21[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21)
trait Product22[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22)
trait Product3[T1, T2, T3]
class (T1, T2, T3)
trait Product4[T1, T2, T3, T4]
class (T1, T2, T3, T4)
trait Product5[T1, T2, T3, T4, T5]
class (T1, T2, T3, T4, T5)
trait Product6[T1, T2, T3, T4, T5, T6]
class (T1, T2, T3, T4, T5, T6)
trait Product7[T1, T2, T3, T4, T5, T6, T7]
class (T1, T2, T3, T4, T5, T6, T7)
trait Product8[T1, T2, T3, T4, T5, T6, T7, T8]
class (T1, T2, T3, T4, T5, T6, T7, T8)
trait Product9[T1, T2, T3, T4, T5, T6, T7, T8, T9]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9)
trait Tuple
object EmptyTuple
class H *: T
Show all
final abstract class Float extends AnyVal

Float, a 32-bit IEEE-754 floating point number (equivalent to Java's float primitive type) is a subtype of scala.AnyVal.

Float, a 32-bit IEEE-754 floating point number (equivalent to Java's float primitive type) is a subtype of scala.AnyVal. Instances of Float are not represented by an object in the underlying runtime system.

There is an implicit conversion from scala.Float => scala.runtime.RichFloat which provides useful non-primitive operations.

Attributes

Companion
object
Source
Float.scala
Supertypes
class AnyVal
trait Matchable
class Any
object Float

Attributes

Companion
class
Source
Float.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Float.type
object Function

A module defining utility methods for higher-order functional programming.

A module defining utility methods for higher-order functional programming.

Attributes

Source
Function.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Function.type
trait Function0[+R] extends AnyRef

A function of 0 parameters.

A function of 0 parameters.

In the following example, the definition of greeting is shorthand, conceptually, for the anonymous class definition anonfun0, although the implementation details of how the function value is constructed may differ:

object Main extends App {
  val name = "world"
  val greeting = () => s"hello, $name"

  val anonfun0 = new Function0[String] {
    def apply(): String = s"hello, $name"
  }
  assert(greeting() == anonfun0())
}

Attributes

Source
Function0.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class FromJavaSupplier[T]
trait Reference[T]
trait ReferenceWrapper[T]
class PhantomReference[T]
class SoftReference[T]
class WeakReference[T]
Show all
Self type
() => R
object Function1

Attributes

Companion
trait
Source
Function1.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Function1.type
trait Function1[-T1, +R] extends AnyRef

A function of 1 parameter.

A function of 1 parameter.

In the following example, the definition of succ is shorthand, conceptually, for the anonymous class definition anonfun1, although the implementation details of how the function value is constructed may differ:

object Main extends App {
  val succ = (x: Int) => x + 1
  val anonfun1 = new Function1[Int, Int] {
    def apply(x: Int): Int = x + 1
  }
  assert(succ(0) == anonfun1(0))
}

Note that the difference between Function1 and scala.PartialFunction is that the latter can specify inputs which it will not handle.

Attributes

Companion
object
Source
Function1.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
trait SetOps[A, CC, C]
trait SetOps[A, CC, C]
trait Set[A]
class AbstractSet[A]
class BitSet
class BitSet1
class BitSet2
class BitSetN
class HashSet[A]
class ListSet[A]
class Set1[A]
class Set2[A]
class Set3[A]
class Set4[A]
class TreeSet[A]
class ValueSet
trait SortedSet[A]
trait SortedSetOps[A, CC, C]
trait StrictOptimizedSortedSetOps[A, CC, C]
trait StrictOptimizedSetOps[A, CC, C]
trait SetOps[A, CC, C]
class HashSet[A]
class LinkedHashSet[A]
trait Set[A]
class AbstractSet[A]
class BitSet
class TreeSet[A]
trait SortedSet[A]
trait SortedSetOps[A, CC, C]
trait Set[A]
class AbstractSet[A]
trait SortedSet[A]
trait BitSet
trait SortedSetOps[A, CC, C]
trait BitSetOps[C]
trait SortedSetFactoryDefaults[A, CC, WithFilterCC]
trait StrictOptimizedSortedSetOps[A, CC, C]
trait StrictOptimizedSetOps[A, CC, C]
class FromJavaConsumer[T]
class FromJavaFunction[T, R]
class AbstractFunction1[T1, R]
class From <:< To
class From =:= To
class Conversion[T, U]
trait PartialFunction[A, B]
trait MapOps[K, V, CC, C]
trait MapOps[K, V, CC, C]
trait Map[K, V]
class AbstractMap[K, V]
class HashMap[K, V]
class IntMap[T]
class ListMap[K, V]
class LongMap[T]
class Map1[K, V]
class Map2[K, V]
class Map3[K, V]
class Map4[K, V]
class WithDefault[K, V]
class WithDefault[K, V]
class TreeMap[K, V]
class TreeSeqMap[K, V]
class VectorMap[K, V]
trait SeqMap[K, V]
trait SortedMap[K, V]
trait SortedMapOps[K, V, CC, C]
trait StrictOptimizedSortedMapOps[K, V, CC, C]
trait StrictOptimizedMapOps[K, V, CC, C]
trait MapOps[K, V, CC, C]
class TrieMap[K, V]
class AnyRefMap[K, V]
class CollisionProofHashMap[K, V]
class HashMap[K, V]
class LinkedHashMap[K, V]
class ListMap[K, V]
class LongMap[V]
trait Map[K, V]
trait Map[K, V]
class AbstractMap[K, V]
class WithDefault[K, V]
class WithDefault[K, V]
class OpenHashMap[Key, Value]
class TreeMap[K, V]
trait MultiMap[K, V]
trait SeqMap[K, V]
trait SortedMap[K, V]
trait SortedMapOps[K, V, CC, C]
trait Map[K, V]
class AbstractMap[K, V]
trait DefaultMap[K, V]
trait SeqMap[K, V]
trait SortedMap[K, V]
trait MapFactoryDefaults[K, V, CC, WithFilterCC]
class WeakHashMap[K, V]
trait MapView[K, V]
class AbstractMapView[K, V]
class Filter[K, V]
class FilterKeys[K, V]
class Id[K, V]
class MapValues[K, V, W]
class TapEach[K, V, U]
trait SortedMapFactoryDefaults[K, V, CC, WithFilterCC, UnsortedCC]
trait SortedMapOps[K, V, CC, C]
trait StrictOptimizedSortedMapOps[K, V, CC, C]
trait StrictOptimizedMapOps[K, V, CC, C]
trait Seq[A]
trait Seq[A]
class AbstractSeq[A]
class ArraySeq[A]
class ofBoolean
class ofByte
class ofChar
class ofDouble
class ofFloat
class ofInt
class ofLong
class ofRef[T]
class ofShort
class ofUnit
class LazyList[A]
class List[A]
class ::[A]
object Nil
class NumericRange[T]
class Exclusive[T]
class Inclusive[T]
class Queue[A]
class Range
class Exclusive
class Inclusive
class Stream[A]
class Cons[A]
object Empty
class Vector[A]
trait IndexedSeq[A]
trait LinearSeq[A]
trait Seq[A]
class AbstractSeq[A]
class AbstractBuffer[A]
class ArrayBuffer[A]
class ArrayDeque[A]
class Queue[A]
class Stack[A]
class ListBuffer[A]
class UnrolledBuffer[T]
class ArraySeq[T]
class ofBoolean
class ofByte
class ofChar
class ofDouble
class ofFloat
class ofInt
class ofLong
class ofRef[T]
class ofShort
class ofUnit
trait Buffer[A]
trait IndexedBuffer[A]
trait IndexedSeq[T]
class Accumulator[A, CC, C]
class AnyAccumulator[A]
class AbstractSeq[A]
trait IndexedSeq[A]
trait LinearSeq[A]
Show all
Self type
T1 => R
trait Function10[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, -T10, +R] extends AnyRef

A function of 10 parameters.

A function of 10 parameters.

Attributes

Source
Function10.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, R]
Self type
(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10) => R
trait Function11[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, -T10, -T11, +R] extends AnyRef

A function of 11 parameters.

A function of 11 parameters.

Attributes

Source
Function11.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction11[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, R]
Self type
(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11) => R
trait Function12[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, -T10, -T11, -T12, +R] extends AnyRef

A function of 12 parameters.

A function of 12 parameters.

Attributes

Source
Function12.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction12[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, R]
Self type
(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12) => R
trait Function13[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, -T10, -T11, -T12, -T13, +R] extends AnyRef

A function of 13 parameters.

A function of 13 parameters.

Attributes

Source
Function13.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction13[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, R]
Self type
(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13) => R
trait Function14[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, -T10, -T11, -T12, -T13, -T14, +R] extends AnyRef

A function of 14 parameters.

A function of 14 parameters.

Attributes

Source
Function14.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction14[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, R]
Self type
(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14) => R
trait Function15[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, -T10, -T11, -T12, -T13, -T14, -T15, +R] extends AnyRef

A function of 15 parameters.

A function of 15 parameters.

Attributes

Source
Function15.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction15[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, R]
Self type
(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15) => R
trait Function16[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, -T10, -T11, -T12, -T13, -T14, -T15, -T16, +R] extends AnyRef

A function of 16 parameters.

A function of 16 parameters.

Attributes

Source
Function16.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction16[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, R]
Self type
(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16) => R
trait Function17[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, -T10, -T11, -T12, -T13, -T14, -T15, -T16, -T17, +R] extends AnyRef

A function of 17 parameters.

A function of 17 parameters.

Attributes

Source
Function17.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction17[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, R]
Self type
(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17) => R
trait Function18[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, -T10, -T11, -T12, -T13, -T14, -T15, -T16, -T17, -T18, +R] extends AnyRef

A function of 18 parameters.

A function of 18 parameters.

Attributes

Source
Function18.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction18[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, R]
Self type
(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18) => R
trait Function19[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, -T10, -T11, -T12, -T13, -T14, -T15, -T16, -T17, -T18, -T19, +R] extends AnyRef

A function of 19 parameters.

A function of 19 parameters.

Attributes

Source
Function19.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction19[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, R]
Self type
(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19) => R
trait Function2[-T1, -T2, +R] extends AnyRef

A function of 2 parameters.

A function of 2 parameters.

In the following example, the definition of max is shorthand, conceptually, for the anonymous class definition anonfun2, although the implementation details of how the function value is constructed may differ:

object Main extends App {
  val max = (x: Int, y: Int) => if (x < y) y else x

  val anonfun2 = new Function2[Int, Int, Int] {
    def apply(x: Int, y: Int): Int = if (x < y) y else x
  }
  assert(max(0, 1) == anonfun2(0, 1))
}

Attributes

Source
Function2.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class FromJavaBiConsumer[T, U]
class FromJavaBiFunction[T, U, R]
class FromJavaBiPredicate[T, U]
class AbstractFunction2[T1, T2, R]
Show all
Self type
(T1, T2) => R
trait Function20[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, -T10, -T11, -T12, -T13, -T14, -T15, -T16, -T17, -T18, -T19, -T20, +R] extends AnyRef

A function of 20 parameters.

A function of 20 parameters.

Attributes

Source
Function20.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction20[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, R]
Self type
(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20) => R
trait Function21[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, -T10, -T11, -T12, -T13, -T14, -T15, -T16, -T17, -T18, -T19, -T20, -T21, +R] extends AnyRef

A function of 21 parameters.

A function of 21 parameters.

Attributes

Source
Function21.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction21[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, R]
Self type
(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21) => R
trait Function22[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, -T10, -T11, -T12, -T13, -T14, -T15, -T16, -T17, -T18, -T19, -T20, -T21, -T22, +R] extends AnyRef

A function of 22 parameters.

A function of 22 parameters.

Attributes

Source
Function22.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction22[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22, R]
Self type
(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22) => R
trait Function3[-T1, -T2, -T3, +R] extends AnyRef

A function of 3 parameters.

A function of 3 parameters.

Attributes

Source
Function3.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction3[T1, T2, T3, R]
Self type
(T1, T2, T3) => R
trait Function4[-T1, -T2, -T3, -T4, +R] extends AnyRef

A function of 4 parameters.

A function of 4 parameters.

Attributes

Source
Function4.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction4[T1, T2, T3, T4, R]
Self type
(T1, T2, T3, T4) => R
trait Function5[-T1, -T2, -T3, -T4, -T5, +R] extends AnyRef

A function of 5 parameters.

A function of 5 parameters.

Attributes

Source
Function5.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction5[T1, T2, T3, T4, T5, R]
Self type
(T1, T2, T3, T4, T5) => R
trait Function6[-T1, -T2, -T3, -T4, -T5, -T6, +R] extends AnyRef

A function of 6 parameters.

A function of 6 parameters.

Attributes

Source
Function6.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction6[T1, T2, T3, T4, T5, T6, R]
Self type
(T1, T2, T3, T4, T5, T6) => R
trait Function7[-T1, -T2, -T3, -T4, -T5, -T6, -T7, +R] extends AnyRef

A function of 7 parameters.

A function of 7 parameters.

Attributes

Source
Function7.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction7[T1, T2, T3, T4, T5, T6, T7, R]
Self type
(T1, T2, T3, T4, T5, T6, T7) => R
trait Function8[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, +R] extends AnyRef

A function of 8 parameters.

A function of 8 parameters.

Attributes

Source
Function8.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction8[T1, T2, T3, T4, T5, T6, T7, T8, R]
Self type
(T1, T2, T3, T4, T5, T6, T7, T8) => R
trait Function9[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, +R] extends AnyRef

A function of 9 parameters.

A function of 9 parameters.

Attributes

Source
Function9.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
class AbstractFunction9[T1, T2, T3, T4, T5, T6, T7, T8, T9, R]
Self type
(T1, T2, T3, T4, T5, T6, T7, T8, T9) => R
object IArray

An immutable array. An IArray[T] has the same representation as an Array[T], but it cannot be updated. Unlike regular arrays, immutable arrays are covariant.

An immutable array. An IArray[T] has the same representation as an Array[T], but it cannot be updated. Unlike regular arrays, immutable arrays are covariant.

Attributes

Source
IArray.scala
Supertypes
class Object
trait Matchable
class Any
Self type
IArray.type
final abstract class Int extends AnyVal

Int, a 32-bit signed integer (equivalent to Java's int primitive type) is a subtype of scala.AnyVal.

Int, a 32-bit signed integer (equivalent to Java's int primitive type) is a subtype of scala.AnyVal. Instances of Int are not represented by an object in the underlying runtime system.

There is an implicit conversion from scala.Int => scala.runtime.RichInt which provides useful non-primitive operations.

Attributes

Companion
object
Source
Int.scala
Supertypes
class AnyVal
trait Matchable
class Any
object Int

Attributes

Companion
class
Source
Int.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Int.type
final abstract class Long extends AnyVal

Long, a 64-bit signed integer (equivalent to Java's long primitive type) is a subtype of scala.AnyVal.

Long, a 64-bit signed integer (equivalent to Java's long primitive type) is a subtype of scala.AnyVal. Instances of Long are not represented by an object in the underlying runtime system.

There is an implicit conversion from scala.Long => scala.runtime.RichLong which provides useful non-primitive operations.

Attributes

Companion
object
Source
Long.scala
Supertypes
class AnyVal
trait Matchable
class Any
object Long

Attributes

Companion
class
Source
Long.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Long.type
final class MatchError(obj: Any) extends RuntimeException

This class implements errors which are thrown whenever an object doesn't match any pattern of a pattern matching expression.

This class implements errors which are thrown whenever an object doesn't match any pattern of a pattern matching expression.

Attributes

Source
MatchError.scala
Supertypes
class Exception
class Throwable
trait Serializable
class Object
trait Matchable
class Any
Show all
open class Matchable

The base trait of types that can be safely pattern matched against.

The base trait of types that can be safely pattern matched against.

See https://docs.scala-lang.org/scala3/reference/other-new-features/matchable.html.

Attributes

Supertypes
class Any
sealed trait NonEmptyTuple extends Tuple

Tuple of arbitrary non-zero arity

Tuple of arbitrary non-zero arity

Attributes

Source
Tuple.scala
Supertypes
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
Known subtypes
class H *: T
case object None extends Option[Nothing]

This case object represents non-existent values.

This case object represents non-existent values.

Attributes

Source
Option.scala
Supertypes
trait Singleton
trait Product
trait Mirror
class Option[Nothing]
trait Serializable
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
Self type
None.type
final class NotImplementedError(msg: String) extends Error

Throwing this exception can be a temporary replacement for a method body that remains to be implemented.

Throwing this exception can be a temporary replacement for a method body that remains to be implemented. For instance, the exception is thrown by Predef.???.

Attributes

Source
NotImplementedError.scala
Supertypes
class Error
class Throwable
trait Serializable
class Object
trait Matchable
class Any
Show all
final abstract open class Nothing

Nothing is - together with scala.Null - at the bottom of Scala's type hierarchy.

Nothing is - together with scala.Null - at the bottom of Scala's type hierarchy.

Nothing is a subtype of every other type (including scala.Null); there exist no instances of this type. Although type Nothing is uninhabited, it is nevertheless useful in several ways. For instance, the Scala library defines a value scala.collection.immutable.Nil of type List[Nothing]. Because lists are covariant in Scala, this makes scala.collection.immutable.Nil an instance of List[T], for any element of type T.

Another usage for Nothing is the return type for methods which never return normally. One example is method error in scala.sys, which always throws an exception.

Attributes

Supertypes
class Any
final abstract open class Null

Null is - together with scala.Nothing - at the bottom of the Scala type hierarchy.

Null is - together with scala.Nothing - at the bottom of the Scala type hierarchy.

Null is the type of the null literal. It is a subtype of every type except those of value classes. Value classes are subclasses of AnyVal, which includes primitive types such as Int, Boolean, and user-defined value classes.

Since Null is not a subtype of value types, null is not a member of any such type. For instance, it is not possible to assign null to a variable of type scala.Int.

Attributes

Supertypes
class Object
trait Matchable
class Any
object Option

Attributes

Companion
class
Source
Option.scala
Supertypes
trait Sum
trait Mirror
class Object
trait Matchable
class Any
Self type
Option.type
sealed abstract class Option[+A] extends IterableOnce[A], Product, Serializable

Represents optional values.

Represents optional values. Instances of Option are either an instance of $some or the object $none.

The most idiomatic way to use an $option instance is to treat it as a collection or monad and use map,flatMap, filter, or foreach:

val name: Option[String] = request getParameter "name"
val upper = name map { _.trim } filter { _.length != 0 } map { _.toUpperCase }
println(upper getOrElse "")

Note that this is equivalent to 

val upper = for {
  name <- request getParameter "name"
  trimmed <- Some(name.trim)
  upper <- Some(trimmed.toUpperCase) if trimmed.length != 0
} yield upper
println(upper getOrElse "")

Because of how for comprehension works, if $none is returned from request.getParameter, the entire expression results in $none

This allows for sophisticated chaining of $option values without having to check for the existence of a value.

These are useful methods that exist for both $some and $none. - isDefined — True if not empty - isEmpty — True if empty - nonEmpty — True if not empty - orElse — Evaluate and return alternate optional value if empty - getOrElse — Evaluate and return alternate value if empty - get — Return value, throw exception if empty - fold — Apply function on optional value, return default if empty - map — Apply a function on the optional value - flatMap — Same as map but function must return an optional value - foreach — Apply a procedure on option value - collect — Apply partial pattern match on optional value - filter — An optional value satisfies predicate - filterNot — An optional value doesn't satisfy predicate - exists — Apply predicate on optional value, or false if empty - forall — Apply predicate on optional value, or true if empty - contains — Checks if value equals optional value, or false if empty - zip — Combine two optional values to make a paired optional value - unzip — Split an optional pair to two optional values - unzip3 — Split an optional triple to three optional values - toList — Unary list of optional value, otherwise the empty list

A less-idiomatic way to use $option values is via pattern matching: 

val nameMaybe = request getParameter "name"
nameMaybe match {
  case Some(name) =>
    println(name.trim.toUppercase)
  case None =>
    println("No name value")
}

Interacting with code that can occasionally return null can be safely wrapped in $option to become $none and $some otherwise. 

val abc = new java.util.HashMap[Int, String]
abc.put(1, "A")
bMaybe = Option(abc.get(2))
bMaybe match {
 case Some(b) =>
   println(s"Found $b")
 case None =>
   println("Not found")
}

Attributes

Note

Many of the methods in here are duplicative with those in the Iterable hierarchy, but they are duplicated for a reason: the implicit conversion tends to leave one with an Iterable in situations where one could have retained an Option.

Companion
object
Source
Option.scala
Supertypes
trait Serializable
trait Product
trait Equals
trait IterableOnce[A]
class Object
trait Matchable
class Any
Show all
Known subtypes
object None
class Some[A]
Self type
Option[A]
trait PartialFunction[-A, +B] extends A => B

A partial function of type PartialFunction[A, B] is a unary function where the domain does not necessarily include all values of type A.

A partial function of type PartialFunction[A, B] is a unary function where the domain does not necessarily include all values of type A. The function isDefinedAt allows to test dynamically if a value is in the domain of the function.

Even if isDefinedAt returns true for an a: A, calling apply(a) may still throw an exception, so the following code is legal:

val f: PartialFunction[Int, Any] = { case x => x / 0 }   // ArithmeticException: / by zero

It is the responsibility of the caller to call isDefinedAt before calling apply, because if isDefinedAt is false, it is not guaranteed apply will throw an exception to indicate an error condition. If an exception is not thrown, evaluation may result in an arbitrary value.

The usual way to respect this contract is to call applyOrElse, which is expected to be more efficient than calling both isDefinedAt and apply.

The main distinction between PartialFunction and scala.Function1 is that the user of a PartialFunction may choose to do something different with input that is declared to be outside its domain. For example:

val sample = 1 to 10
def isEven(n: Int) = n % 2 == 0
val eveningNews: PartialFunction[Int, String] = {
  case x if isEven(x) => s"$x is even"
}

// The method collect is described as "filter + map"
// because it uses a PartialFunction to select elements
// to which the function is applied.
val evenNumbers = sample.collect(eveningNews)

val oddlyEnough: PartialFunction[Int, String] = {
  case x if !isEven(x) => s"$x is odd"
}

// The method orElse allows chaining another PartialFunction
// to handle input outside the declared domain.
val numbers = sample.map(eveningNews orElse oddlyEnough)

// same as
val numbers = sample.map(n => eveningNews.applyOrElse(n, oddlyEnough))

val half: PartialFunction[Int, Int] = {
  case x if isEven(x) => x / 2
}

// Calculating the domain of a composition can be expensive.
val oddByHalf = half.andThen(oddlyEnough)

// Invokes `half.apply` on even elements!
val oddBalls = sample.filter(oddByHalf.isDefinedAt)

// Better than filter(oddByHalf.isDefinedAt).map(oddByHalf)
val oddBalls = sample.collect(oddByHalf)

// Providing "default" values.
val oddsAndEnds = sample.map(n => oddByHalf.applyOrElse(n, (i: Int) => s"[$i]"))

Attributes

Note

Optional Functions, PartialFunctions and extractor objects can be converted to each other as shown in the following table.  

How to convert ...

to a PartialFunction

to an optional Function

to an extractor

from a PartialFunction

Predef.identity

lift

Predef.identity

from optional Function

Function1.UnliftOps#unlift or Function.unlift

Predef.identity

Function1.UnliftOps#unlift

from an extractor

{ case extractor(x) => x }

extractor.unapply _

Predef.identity

 

Companion
object
Source
PartialFunction.scala
Supertypes
trait A => B
class Object
trait Matchable
class Any
Known subtypes
trait MapOps[K, V, CC, C]
trait MapOps[K, V, CC, C]
trait Map[K, V]
class AbstractMap[K, V]
class HashMap[K, V]
class IntMap[T]
class ListMap[K, V]
class LongMap[T]
class Map1[K, V]
class Map2[K, V]
class Map3[K, V]
class Map4[K, V]
class WithDefault[K, V]
class WithDefault[K, V]
class TreeMap[K, V]
class TreeSeqMap[K, V]
class VectorMap[K, V]
trait SeqMap[K, V]
trait SortedMap[K, V]
trait SortedMapOps[K, V, CC, C]
trait StrictOptimizedSortedMapOps[K, V, CC, C]
trait StrictOptimizedMapOps[K, V, CC, C]
trait MapOps[K, V, CC, C]
class TrieMap[K, V]
class AnyRefMap[K, V]
class CollisionProofHashMap[K, V]
class HashMap[K, V]
class LinkedHashMap[K, V]
class ListMap[K, V]
class LongMap[V]
trait Map[K, V]
trait Map[K, V]
class AbstractMap[K, V]
class WithDefault[K, V]
class WithDefault[K, V]
class OpenHashMap[Key, Value]
class TreeMap[K, V]
trait MultiMap[K, V]
trait SeqMap[K, V]
trait SortedMap[K, V]
trait SortedMapOps[K, V, CC, C]
trait Map[K, V]
class AbstractMap[K, V]
trait DefaultMap[K, V]
trait SeqMap[K, V]
trait SortedMap[K, V]
trait MapFactoryDefaults[K, V, CC, WithFilterCC]
class WeakHashMap[K, V]
trait MapView[K, V]
class AbstractMapView[K, V]
class Filter[K, V]
class FilterKeys[K, V]
class Id[K, V]
class MapValues[K, V, W]
class TapEach[K, V, U]
trait SortedMapFactoryDefaults[K, V, CC, WithFilterCC, UnsortedCC]
trait SortedMapOps[K, V, CC, C]
trait StrictOptimizedSortedMapOps[K, V, CC, C]
trait StrictOptimizedMapOps[K, V, CC, C]
trait Seq[A]
trait Seq[A]
class AbstractSeq[A]
class ArraySeq[A]
class ofBoolean
class ofByte
class ofChar
class ofDouble
class ofFloat
class ofInt
class ofLong
class ofRef[T]
class ofShort
class ofUnit
class LazyList[A]
class List[A]
class ::[A]
object Nil
class NumericRange[T]
class Exclusive[T]
class Inclusive[T]
class Queue[A]
class Range
class Exclusive
class Inclusive
class Stream[A]
class Cons[A]
object Empty
class Vector[A]
trait IndexedSeq[A]
trait LinearSeq[A]
trait Seq[A]
class AbstractSeq[A]
class AbstractBuffer[A]
class ArrayBuffer[A]
class ArrayDeque[A]
class Queue[A]
class Stack[A]
class ListBuffer[A]
class UnrolledBuffer[T]
class ArraySeq[T]
class ofBoolean
class ofByte
class ofChar
class ofDouble
class ofFloat
class ofInt
class ofLong
class ofRef[T]
class ofShort
class ofUnit
trait Buffer[A]
trait IndexedBuffer[A]
trait IndexedSeq[T]
class Accumulator[A, CC, C]
class AnyAccumulator[A]
class AbstractSeq[A]
trait IndexedSeq[A]
trait LinearSeq[A]
Show all
Self type
object PartialFunction

A few handy operations which leverage the extra bit of information available in partial functions.

A few handy operations which leverage the extra bit of information available in partial functions. Examples:

import PartialFunction._

def strangeConditional(other: Any): Boolean = cond(other) {
  case x: String if x == "abc" || x == "def"  => true
  case x: Int => true
}
def onlyInt(v: Any): Option[Int] = condOpt(v) { case x: Int => x }

Attributes

Companion
trait
Source
PartialFunction.scala
Supertypes
class Object
trait Matchable
class Any
Self type
trait PolyFunction

Marker trait for polymorphic function types.

Marker trait for polymorphic function types.

This is the only trait that can be refined with a polymorphic method, as long as that method is called apply, e.g.: PolyFunction { def apply[T_1, ..., T_M](x_1: P_1, ..., x_N: P_N): R } This type will be erased to FunctionN.

Attributes

Source
PolyFunction.scala
Supertypes
class Object
trait Matchable
class Any
object Predef

The Predef object provides definitions that are accessible in all Scala compilation units without explicit qualification.

The Predef object provides definitions that are accessible in all Scala compilation units without explicit qualification.

Commonly Used Types

Predef provides type aliases for types which are commonly used, such as the immutable collection types scala.collection.immutable.Map and scala.collection.immutable.Set.

Console Output

For basic console output, Predef provides convenience methods print and println, which are aliases of the methods in the object scala.Console.

Assertions

A set of assert functions are provided for use as a way to document and dynamically check invariants in code. Invocations of assert can be elided at compile time by providing the command line option -Xdisable-assertions, which raises -Xelide-below above elidable.ASSERTION, to the scalac command.

Variants of assert intended for use with static analysis tools are also provided: assume, require and ensuring. require and ensuring are intended for use as a means of design-by-contract style specification of pre- and post-conditions on functions, with the intention that these specifications could be consumed by a static analysis tool. For instance,

def addNaturals(nats: List[Int]): Int = {
  require(nats forall (_ >= 0), "List contains negative numbers")
  nats.foldLeft(0)(_ + _)
} ensuring(_ >= 0)

The declaration of addNaturals states that the list of integers passed should only contain natural numbers (i.e. non-negative), and that the result returned will also be natural. require is distinct from assert in that if the condition fails, then the caller of the function is to blame rather than a logical error having been made within addNaturals itself. ensuring is a form of assert that declares the guarantee the function is providing with regards to its return value.

Implicit Conversions

A number of commonly applied implicit conversions are also defined here, and in the parent type scala.LowPriorityImplicits. Implicit conversions are provided for the "widening" of numeric values, for instance, converting a Short value to a Long value as required, and to add additional higher-order functions to Array values. These are described in more detail in the documentation of scala.Array.

Attributes

Source
Predef.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Predef.type
trait Product extends Equals

Base trait for all products, which in the standard library include at least scala.Product1 through scala.Product22 and therefore also their subclasses scala.Tuple1 through scala.Tuple22.

Base trait for all products, which in the standard library include at least scala.Product1 through scala.Product22 and therefore also their subclasses scala.Tuple1 through scala.Tuple22. In addition, all case classes implement Product with synthetically generated methods.

Attributes

Source
Product.scala
Supertypes
trait Equals
class Any
Known subtypes
trait Enum
trait EnumValue
class TupleXXL
class Either[A, B]
class Left[A, B]
class Right[A, B]
class Try[T]
class Failure[T]
class Success[T]
class Option[A]
object None
class Some[A]
trait Product1[T1]
class Tuple1[T1]
trait Product10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10)
trait Product11[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11)
trait Product12[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12)
trait Product13[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13)
trait Product14[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14)
trait Product15[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15)
trait Product16[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16)
trait Product17[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17)
trait Product18[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18)
trait Product19[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19)
trait Product2[T1, T2]
class (T1, T2)
trait Product20[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20)
trait Product21[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21)
trait Product22[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22)
trait Product3[T1, T2, T3]
class (T1, T2, T3)
trait Product4[T1, T2, T3, T4]
class (T1, T2, T3, T4)
trait Product5[T1, T2, T3, T4, T5]
class (T1, T2, T3, T4, T5)
trait Product6[T1, T2, T3, T4, T5, T6]
class (T1, T2, T3, T4, T5, T6)
trait Product7[T1, T2, T3, T4, T5, T6, T7]
class (T1, T2, T3, T4, T5, T6, T7)
trait Product8[T1, T2, T3, T4, T5, T6, T7, T8]
class (T1, T2, T3, T4, T5, T6, T7, T8)
trait Product9[T1, T2, T3, T4, T5, T6, T7, T8, T9]
class (T1, T2, T3, T4, T5, T6, T7, T8, T9)
trait Tuple
object EmptyTuple
class H *: T
Show all
object Product1

Attributes

Companion
trait
Source
Product1.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product1.type
trait Product1[+T1] extends Product

Product1 is a Cartesian product of 1 component.

Product1 is a Cartesian product of 1 component.

Attributes

Companion
object
Source
Product1.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class Tuple1[T1]
object Product10

Attributes

Companion
trait
Source
Product10.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product10.type
trait Product10[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10] extends Product

Product10 is a Cartesian product of 10 components.

Product10 is a Cartesian product of 10 components.

Attributes

Companion
object
Source
Product10.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10)
object Product11

Attributes

Companion
trait
Source
Product11.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product11.type
trait Product11[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11] extends Product

Product11 is a Cartesian product of 11 components.

Product11 is a Cartesian product of 11 components.

Attributes

Companion
object
Source
Product11.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11)
object Product12

Attributes

Companion
trait
Source
Product12.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product12.type
trait Product12[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12] extends Product

Product12 is a Cartesian product of 12 components.

Product12 is a Cartesian product of 12 components.

Attributes

Companion
object
Source
Product12.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12)
object Product13

Attributes

Companion
trait
Source
Product13.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product13.type
trait Product13[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13] extends Product

Product13 is a Cartesian product of 13 components.

Product13 is a Cartesian product of 13 components.

Attributes

Companion
object
Source
Product13.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13)
object Product14

Attributes

Companion
trait
Source
Product14.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product14.type
trait Product14[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14] extends Product

Product14 is a Cartesian product of 14 components.

Product14 is a Cartesian product of 14 components.

Attributes

Companion
object
Source
Product14.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14)
object Product15

Attributes

Companion
trait
Source
Product15.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product15.type
trait Product15[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15] extends Product

Product15 is a Cartesian product of 15 components.

Product15 is a Cartesian product of 15 components.

Attributes

Companion
object
Source
Product15.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15)
object Product16

Attributes

Companion
trait
Source
Product16.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product16.type
trait Product16[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15, +T16] extends Product

Product16 is a Cartesian product of 16 components.

Product16 is a Cartesian product of 16 components.

Attributes

Companion
object
Source
Product16.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16)
object Product17

Attributes

Companion
trait
Source
Product17.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product17.type
trait Product17[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15, +T16, +T17] extends Product

Product17 is a Cartesian product of 17 components.

Product17 is a Cartesian product of 17 components.

Attributes

Companion
object
Source
Product17.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17)
object Product18

Attributes

Companion
trait
Source
Product18.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product18.type
trait Product18[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15, +T16, +T17, +T18] extends Product

Product18 is a Cartesian product of 18 components.

Product18 is a Cartesian product of 18 components.

Attributes

Companion
object
Source
Product18.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18)
object Product19

Attributes

Companion
trait
Source
Product19.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product19.type
trait Product19[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15, +T16, +T17, +T18, +T19] extends Product

Product19 is a Cartesian product of 19 components.

Product19 is a Cartesian product of 19 components.

Attributes

Companion
object
Source
Product19.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19)
object Product2

Attributes

Companion
trait
Source
Product2.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product2.type
trait Product2[+T1, +T2] extends Product

Product2 is a Cartesian product of 2 components.

Product2 is a Cartesian product of 2 components.

Attributes

Companion
object
Source
Product2.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2)
object Product20

Attributes

Companion
trait
Source
Product20.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product20.type
trait Product20[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15, +T16, +T17, +T18, +T19, +T20] extends Product

Product20 is a Cartesian product of 20 components.

Product20 is a Cartesian product of 20 components.

Attributes

Companion
object
Source
Product20.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20)
object Product21

Attributes

Companion
trait
Source
Product21.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product21.type
trait Product21[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15, +T16, +T17, +T18, +T19, +T20, +T21] extends Product

Product21 is a Cartesian product of 21 components.

Product21 is a Cartesian product of 21 components.

Attributes

Companion
object
Source
Product21.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21)
object Product22

Attributes

Companion
trait
Source
Product22.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product22.type
trait Product22[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15, +T16, +T17, +T18, +T19, +T20, +T21, +T22] extends Product

Product22 is a Cartesian product of 22 components.

Product22 is a Cartesian product of 22 components.

Attributes

Companion
object
Source
Product22.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22)
object Product3

Attributes

Companion
trait
Source
Product3.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product3.type
trait Product3[+T1, +T2, +T3] extends Product

Product3 is a Cartesian product of 3 components.

Product3 is a Cartesian product of 3 components.

Attributes

Companion
object
Source
Product3.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3)
object Product4

Attributes

Companion
trait
Source
Product4.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product4.type
trait Product4[+T1, +T2, +T3, +T4] extends Product

Product4 is a Cartesian product of 4 components.

Product4 is a Cartesian product of 4 components.

Attributes

Companion
object
Source
Product4.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4)
object Product5

Attributes

Companion
trait
Source
Product5.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product5.type
trait Product5[+T1, +T2, +T3, +T4, +T5] extends Product

Product5 is a Cartesian product of 5 components.

Product5 is a Cartesian product of 5 components.

Attributes

Companion
object
Source
Product5.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5)
object Product6

Attributes

Companion
trait
Source
Product6.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product6.type
trait Product6[+T1, +T2, +T3, +T4, +T5, +T6] extends Product

Product6 is a Cartesian product of 6 components.

Product6 is a Cartesian product of 6 components.

Attributes

Companion
object
Source
Product6.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6)
object Product7

Attributes

Companion
trait
Source
Product7.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product7.type
trait Product7[+T1, +T2, +T3, +T4, +T5, +T6, +T7] extends Product

Product7 is a Cartesian product of 7 components.

Product7 is a Cartesian product of 7 components.

Attributes

Companion
object
Source
Product7.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7)
object Product8

Attributes

Companion
trait
Source
Product8.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product8.type
trait Product8[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8] extends Product

Product8 is a Cartesian product of 8 components.

Product8 is a Cartesian product of 8 components.

Attributes

Companion
object
Source
Product8.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7, T8)
object Product9

Attributes

Companion
trait
Source
Product9.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Product9.type
trait Product9[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9] extends Product

Product9 is a Cartesian product of 9 components.

Product9 is a Cartesian product of 9 components.

Attributes

Companion
object
Source
Product9.scala
Supertypes
trait Product
trait Equals
class Any
Known subtypes
class (T1, T2, T3, T4, T5, T6, T7, T8, T9)
case class ScalaReflectionException(msg: String) extends Exception

An exception that indicates an error during Scala reflection

An exception that indicates an error during Scala reflection

Attributes

Source
package.scala
Supertypes
trait Product
trait Equals
class Exception
class Throwable
trait Serializable
class Object
trait Matchable
class Any
Show all
trait Selectable

A marker trait for objects that support structural selection via selectDynamic and applyDynamic

A marker trait for objects that support structural selection via selectDynamic and applyDynamic

Implementation classes should define, or make available as extension methods, the following two method signatures:

  def selectDynamic(name: String): Any
  def applyDynamic(name: String)(args: Any*): Any =

selectDynamic is invoked for simple selections v.m, whereas applyDynamic is invoked for selections with arguments v.m(...). If there's only one kind of selection, the method supporting the other may be omitted. The applyDynamic can also have a second parameter list of java.lang.Class arguments, i.e. it may alternatively have the signature

  def applyDynamic(name: String, paramClasses: Class[_]*)(args: Any*): Any

In this case the call will synthesize Class arguments for the erasure of all formal parameter types of the method in the structural type.

Attributes

Companion
object
Source
Selectable.scala
Supertypes
class Any
Known subtypes
trait Selectable
object Selectable

Attributes

Companion
trait
Source
Selectable.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Selectable.type
class SerialVersionUID(value: Long) extends ConstantAnnotation

Annotation for specifying the serialVersionUID field of a (serializable) class.

Annotation for specifying the serialVersionUID field of a (serializable) class.

On the JVM, a class with this annotation will receive a private, static, and final field called serialVersionUID with the provided value, which the JVM's serialization mechanism uses to determine serialization compatibility between different versions of a class.

Attributes

See also
Source
SerialVersionUID.scala
Supertypes
class Annotation
class Object
trait Matchable
class Any
Show all
final abstract class Short extends AnyVal

Short, a 16-bit signed integer (equivalent to Java's short primitive type) is a subtype of scala.AnyVal.

Short, a 16-bit signed integer (equivalent to Java's short primitive type) is a subtype of scala.AnyVal. Instances of Short are not represented by an object in the underlying runtime system.

There is an implicit conversion from scala.Short => scala.runtime.RichShort which provides useful non-primitive operations.

Attributes

Companion
object
Source
Short.scala
Supertypes
class AnyVal
trait Matchable
class Any
object Short

Attributes

Companion
class
Source
Short.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Short.type
final open class Singleton

Singleton is used by the compiler as a supertype for singleton types.

Singleton is used by the compiler as a supertype for singleton types. This includes literal types, as they are also singleton types.

scala> object A { val x = 42 }
defined object A

scala> implicitly[A.type <:< Singleton]
res12: A.type <:< Singleton = generalized constraint

scala> implicitly[A.x.type <:< Singleton]
res13: A.x.type <:< Singleton = generalized constraint

scala> implicitly[42 <:< Singleton]
res14: 42 <:< Singleton = generalized constraint

scala> implicitly[Int <:< Singleton]
^
error: Cannot prove that Int <:< Singleton.

Singleton has a special meaning when it appears as an upper bound on a formal type parameter. Normally, type inference in Scala widens singleton types to the underlying non-singleton type. When a type parameter has an explicit upper bound of Singleton, the compiler infers a singleton type.

scala> def check42[T](x: T)(implicit ev: T =:= 42): T = x
check42: [T](x: T)(implicit ev: T =:= 42)T

scala> val x1 = check42(42)
^
error: Cannot prove that Int =:= 42.

scala> def singleCheck42[T <: Singleton](x: T)(implicit ev: T =:= 42): T = x
singleCheck42: [T <: Singleton](x: T)(implicit ev: T =:= 42)T

scala> val x2 = singleCheck42(42)
x2: Int = 42

See also SIP-23 about Literal-based Singleton Types.

Attributes

Supertypes
class Any
final case class Some[+A](value: A) extends Option[A]

Class Some[A] represents existing values of type A.

Class Some[A] represents existing values of type A.

Attributes

Source
Option.scala
Supertypes
class Option[A]
trait Serializable
trait Product
trait Equals
trait IterableOnce[A]
class Object
trait Matchable
class Any
Show all
trait Specializable

A common supertype for companions of specializable types.

A common supertype for companions of specializable types. Should not be extended in user code.

Attributes

Companion
object
Source
Specializable.scala
Supertypes
class Object
trait Matchable
class Any
object Specializable

Attributes

Companion
trait
Source
Specializable.scala
Supertypes
class Object
trait Matchable
class Any
Self type
case class StringContext(parts: String*)

This class provides the basic mechanism to do String Interpolation.

This class provides the basic mechanism to do String Interpolation. String Interpolation allows users to embed variable references directly in *processed* string literals. Here's an example:

val name = "James"
println(s"Hello, $name")  // Hello, James

Any processed string literal is rewritten as an instantiation and method call against this class. For example:

s"Hello, $name"

is rewritten to be:

StringContext("Hello, ", "").s(name)

By default, this class provides the raw, s and f methods as available interpolators.

To provide your own string interpolator, create an implicit class which adds a method to StringContext. Here's an example:

implicit class JsonHelper(private val sc: StringContext) extends AnyVal {
  def json(args: Any*): JSONObject = ...
}
val x: JSONObject = json"{ a: $a }"

Here the JsonHelper extension class implicitly adds the json method to StringContext which can be used for json string literals.

Value parameters

parts

The parts that make up the interpolated string, without the expressions that get inserted by interpolation.

Attributes

Companion
object
Source
StringContext.scala
Supertypes
trait Serializable
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
object StringContext

Attributes

Companion
class
Source
StringContext.scala
Supertypes
trait Product
trait Mirror
class Object
trait Matchable
class Any
Self type
final class Symbol extends Serializable

This class provides a simple way to get unique objects for equal strings.

This class provides a simple way to get unique objects for equal strings. Since symbols are interned, they can be compared using reference equality.

Attributes

Companion
object
Source
Symbol.scala
Supertypes
trait Serializable
class Object
trait Matchable
class Any
object Symbol

Attributes

Companion
class
Source
Symbol.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Symbol.type
sealed trait Tuple extends Product

Tuple of arbitrary arity

Tuple of arbitrary arity

Attributes

Companion
object
Source
Tuple.scala
Supertypes
trait Product
trait Equals
class Object
trait Matchable
class Any
Known subtypes
object EmptyTuple
class H *: T
object Tuple

Attributes

Companion
trait
Source
Tuple.scala
Supertypes
trait Sum
trait Mirror
class Object
trait Matchable
class Any
Self type
Tuple.type
final case class Tuple1[+T1](_1: T1) extends Product1[T1]

A tuple of 1 elements; the canonical representation of a scala.Product1.

A tuple of 1 elements; the canonical representation of a scala.Product1.

Value parameters

_1

Element 1 of this Tuple1

Attributes

Constructor

Create a new tuple with 1 elements.

Source
Tuple1.scala
Supertypes
trait Serializable
trait Product1[T1]
class T1 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple10[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7, _8: T8, _9: T9, _10: T10) extends Product10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10]

A tuple of 10 elements; the canonical representation of a scala.Product10.

A tuple of 10 elements; the canonical representation of a scala.Product10.

Value parameters

_1

Element 1 of this Tuple10

_10

Element 10 of this Tuple10

_2

Element 2 of this Tuple10

_3

Element 3 of this Tuple10

_4

Element 4 of this Tuple10

_5

Element 5 of this Tuple10

_6

Element 6 of this Tuple10

_7

Element 7 of this Tuple10

_8

Element 8 of this Tuple10

_9

Element 9 of this Tuple10

Attributes

Constructor

Create a new tuple with 10 elements. Note that it is more idiomatic to create a Tuple10 via (t1, t2, t3, t4, t5, t6, t7, t8, t9, t10)

Source
Tuple10.scala
Supertypes
trait Serializable
trait Product10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: T8 *: T9 *: T10 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple11[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7, _8: T8, _9: T9, _10: T10, _11: T11) extends Product11[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11]

A tuple of 11 elements; the canonical representation of a scala.Product11.

A tuple of 11 elements; the canonical representation of a scala.Product11.

Value parameters

_1

Element 1 of this Tuple11

_10

Element 10 of this Tuple11

_11

Element 11 of this Tuple11

_2

Element 2 of this Tuple11

_3

Element 3 of this Tuple11

_4

Element 4 of this Tuple11

_5

Element 5 of this Tuple11

_6

Element 6 of this Tuple11

_7

Element 7 of this Tuple11

_8

Element 8 of this Tuple11

_9

Element 9 of this Tuple11

Attributes

Constructor

Create a new tuple with 11 elements. Note that it is more idiomatic to create a Tuple11 via (t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11)

Source
Tuple11.scala
Supertypes
trait Serializable
trait Product11[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: T8 *: T9 *: T10 *: T11 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple12[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7, _8: T8, _9: T9, _10: T10, _11: T11, _12: T12) extends Product12[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12]

A tuple of 12 elements; the canonical representation of a scala.Product12.

A tuple of 12 elements; the canonical representation of a scala.Product12.

Value parameters

_1

Element 1 of this Tuple12

_10

Element 10 of this Tuple12

_11

Element 11 of this Tuple12

_12

Element 12 of this Tuple12

_2

Element 2 of this Tuple12

_3

Element 3 of this Tuple12

_4

Element 4 of this Tuple12

_5

Element 5 of this Tuple12

_6

Element 6 of this Tuple12

_7

Element 7 of this Tuple12

_8

Element 8 of this Tuple12

_9

Element 9 of this Tuple12

Attributes

Constructor

Create a new tuple with 12 elements. Note that it is more idiomatic to create a Tuple12 via (t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12)

Source
Tuple12.scala
Supertypes
trait Serializable
trait Product12[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: T8 *: T9 *: T10 *: T11 *: T12 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple13[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7, _8: T8, _9: T9, _10: T10, _11: T11, _12: T12, _13: T13) extends Product13[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13]

A tuple of 13 elements; the canonical representation of a scala.Product13.

A tuple of 13 elements; the canonical representation of a scala.Product13.

Value parameters

_1

Element 1 of this Tuple13

_10

Element 10 of this Tuple13

_11

Element 11 of this Tuple13

_12

Element 12 of this Tuple13

_13

Element 13 of this Tuple13

_2

Element 2 of this Tuple13

_3

Element 3 of this Tuple13

_4

Element 4 of this Tuple13

_5

Element 5 of this Tuple13

_6

Element 6 of this Tuple13

_7

Element 7 of this Tuple13

_8

Element 8 of this Tuple13

_9

Element 9 of this Tuple13

Attributes

Constructor

Create a new tuple with 13 elements. Note that it is more idiomatic to create a Tuple13 via (t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13)

Source
Tuple13.scala
Supertypes
trait Serializable
trait Product13[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: T8 *: T9 *: T10 *: T11 *: T12 *: T13 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple14[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7, _8: T8, _9: T9, _10: T10, _11: T11, _12: T12, _13: T13, _14: T14) extends Product14[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14]

A tuple of 14 elements; the canonical representation of a scala.Product14.

A tuple of 14 elements; the canonical representation of a scala.Product14.

Value parameters

_1

Element 1 of this Tuple14

_10

Element 10 of this Tuple14

_11

Element 11 of this Tuple14

_12

Element 12 of this Tuple14

_13

Element 13 of this Tuple14

_14

Element 14 of this Tuple14

_2

Element 2 of this Tuple14

_3

Element 3 of this Tuple14

_4

Element 4 of this Tuple14

_5

Element 5 of this Tuple14

_6

Element 6 of this Tuple14

_7

Element 7 of this Tuple14

_8

Element 8 of this Tuple14

_9

Element 9 of this Tuple14

Attributes

Constructor

Create a new tuple with 14 elements. Note that it is more idiomatic to create a Tuple14 via (t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14)

Source
Tuple14.scala
Supertypes
trait Serializable
trait Product14[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: T8 *: T9 *: T10 *: T11 *: T12 *: T13 *: T14 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple15[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7, _8: T8, _9: T9, _10: T10, _11: T11, _12: T12, _13: T13, _14: T14, _15: T15) extends Product15[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15]

A tuple of 15 elements; the canonical representation of a scala.Product15.

A tuple of 15 elements; the canonical representation of a scala.Product15.

Value parameters

_1

Element 1 of this Tuple15

_10

Element 10 of this Tuple15

_11

Element 11 of this Tuple15

_12

Element 12 of this Tuple15

_13

Element 13 of this Tuple15

_14

Element 14 of this Tuple15

_15

Element 15 of this Tuple15

_2

Element 2 of this Tuple15

_3

Element 3 of this Tuple15

_4

Element 4 of this Tuple15

_5

Element 5 of this Tuple15

_6

Element 6 of this Tuple15

_7

Element 7 of this Tuple15

_8

Element 8 of this Tuple15

_9

Element 9 of this Tuple15

Attributes

Constructor

Create a new tuple with 15 elements. Note that it is more idiomatic to create a Tuple15 via (t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15)

Source
Tuple15.scala
Supertypes
trait Serializable
trait Product15[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: T8 *: T9 *: T10 *: T11 *: T12 *: T13 *: T14 *: T15 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple16[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15, +T16](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7, _8: T8, _9: T9, _10: T10, _11: T11, _12: T12, _13: T13, _14: T14, _15: T15, _16: T16) extends Product16[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16]

A tuple of 16 elements; the canonical representation of a scala.Product16.

A tuple of 16 elements; the canonical representation of a scala.Product16.

Value parameters

_1

Element 1 of this Tuple16

_10

Element 10 of this Tuple16

_11

Element 11 of this Tuple16

_12

Element 12 of this Tuple16

_13

Element 13 of this Tuple16

_14

Element 14 of this Tuple16

_15

Element 15 of this Tuple16

_16

Element 16 of this Tuple16

_2

Element 2 of this Tuple16

_3

Element 3 of this Tuple16

_4

Element 4 of this Tuple16

_5

Element 5 of this Tuple16

_6

Element 6 of this Tuple16

_7

Element 7 of this Tuple16

_8

Element 8 of this Tuple16

_9

Element 9 of this Tuple16

Attributes

Constructor

Create a new tuple with 16 elements. Note that it is more idiomatic to create a Tuple16 via (t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16)

Source
Tuple16.scala
Supertypes
trait Serializable
trait Product16[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: T8 *: T9 *: T10 *: T11 *: T12 *: T13 *: T14 *: T15 *: T16 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple17[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15, +T16, +T17](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7, _8: T8, _9: T9, _10: T10, _11: T11, _12: T12, _13: T13, _14: T14, _15: T15, _16: T16, _17: T17) extends Product17[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17]

A tuple of 17 elements; the canonical representation of a scala.Product17.

A tuple of 17 elements; the canonical representation of a scala.Product17.

Value parameters

_1

Element 1 of this Tuple17

_10

Element 10 of this Tuple17

_11

Element 11 of this Tuple17

_12

Element 12 of this Tuple17

_13

Element 13 of this Tuple17

_14

Element 14 of this Tuple17

_15

Element 15 of this Tuple17

_16

Element 16 of this Tuple17

_17

Element 17 of this Tuple17

_2

Element 2 of this Tuple17

_3

Element 3 of this Tuple17

_4

Element 4 of this Tuple17

_5

Element 5 of this Tuple17

_6

Element 6 of this Tuple17

_7

Element 7 of this Tuple17

_8

Element 8 of this Tuple17

_9

Element 9 of this Tuple17

Attributes

Constructor

Create a new tuple with 17 elements. Note that it is more idiomatic to create a Tuple17 via (t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17)

Source
Tuple17.scala
Supertypes
trait Serializable
trait Product17[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: T8 *: T9 *: T10 *: T11 *: T12 *: T13 *: T14 *: T15 *: T16 *: T17 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple18[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15, +T16, +T17, +T18](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7, _8: T8, _9: T9, _10: T10, _11: T11, _12: T12, _13: T13, _14: T14, _15: T15, _16: T16, _17: T17, _18: T18) extends Product18[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18]

A tuple of 18 elements; the canonical representation of a scala.Product18.

A tuple of 18 elements; the canonical representation of a scala.Product18.

Value parameters

_1

Element 1 of this Tuple18

_10

Element 10 of this Tuple18

_11

Element 11 of this Tuple18

_12

Element 12 of this Tuple18

_13

Element 13 of this Tuple18

_14

Element 14 of this Tuple18

_15

Element 15 of this Tuple18

_16

Element 16 of this Tuple18

_17

Element 17 of this Tuple18

_18

Element 18 of this Tuple18

_2

Element 2 of this Tuple18

_3

Element 3 of this Tuple18

_4

Element 4 of this Tuple18

_5

Element 5 of this Tuple18

_6

Element 6 of this Tuple18

_7

Element 7 of this Tuple18

_8

Element 8 of this Tuple18

_9

Element 9 of this Tuple18

Attributes

Constructor

Create a new tuple with 18 elements. Note that it is more idiomatic to create a Tuple18 via (t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18)

Source
Tuple18.scala
Supertypes
trait Serializable
trait Product18[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: T8 *: T9 *: T10 *: T11 *: T12 *: T13 *: T14 *: T15 *: T16 *: T17 *: T18 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple19[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15, +T16, +T17, +T18, +T19](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7, _8: T8, _9: T9, _10: T10, _11: T11, _12: T12, _13: T13, _14: T14, _15: T15, _16: T16, _17: T17, _18: T18, _19: T19) extends Product19[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19]

A tuple of 19 elements; the canonical representation of a scala.Product19.

A tuple of 19 elements; the canonical representation of a scala.Product19.

Value parameters

_1

Element 1 of this Tuple19

_10

Element 10 of this Tuple19

_11

Element 11 of this Tuple19

_12

Element 12 of this Tuple19

_13

Element 13 of this Tuple19

_14

Element 14 of this Tuple19

_15

Element 15 of this Tuple19

_16

Element 16 of this Tuple19

_17

Element 17 of this Tuple19

_18

Element 18 of this Tuple19

_19

Element 19 of this Tuple19

_2

Element 2 of this Tuple19

_3

Element 3 of this Tuple19

_4

Element 4 of this Tuple19

_5

Element 5 of this Tuple19

_6

Element 6 of this Tuple19

_7

Element 7 of this Tuple19

_8

Element 8 of this Tuple19

_9

Element 9 of this Tuple19

Attributes

Constructor

Create a new tuple with 19 elements. Note that it is more idiomatic to create a Tuple19 via (t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18, t19)

Source
Tuple19.scala
Supertypes
trait Serializable
trait Product19[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: T8 *: T9 *: T10 *: T11 *: T12 *: T13 *: T14 *: T15 *: T16 *: T17 *: T18 *: T19 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple2[+T1, +T2](_1: T1, _2: T2) extends Product2[T1, T2]

A tuple of 2 elements; the canonical representation of a scala.Product2.

A tuple of 2 elements; the canonical representation of a scala.Product2.

Value parameters

_1

Element 1 of this Tuple2

_2

Element 2 of this Tuple2

Attributes

Constructor

Create a new tuple with 2 elements. Note that it is more idiomatic to create a Tuple2 via (t1, t2)

Source
Tuple2.scala
Supertypes
trait Serializable
trait Product2[T1, T2]
class T1 *: T2 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple20[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15, +T16, +T17, +T18, +T19, +T20](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7, _8: T8, _9: T9, _10: T10, _11: T11, _12: T12, _13: T13, _14: T14, _15: T15, _16: T16, _17: T17, _18: T18, _19: T19, _20: T20) extends Product20[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20]

A tuple of 20 elements; the canonical representation of a scala.Product20.

A tuple of 20 elements; the canonical representation of a scala.Product20.

Value parameters

_1

Element 1 of this Tuple20

_10

Element 10 of this Tuple20

_11

Element 11 of this Tuple20

_12

Element 12 of this Tuple20

_13

Element 13 of this Tuple20

_14

Element 14 of this Tuple20

_15

Element 15 of this Tuple20

_16

Element 16 of this Tuple20

_17

Element 17 of this Tuple20

_18

Element 18 of this Tuple20

_19

Element 19 of this Tuple20

_2

Element 2 of this Tuple20

_20

Element 20 of this Tuple20

_3

Element 3 of this Tuple20

_4

Element 4 of this Tuple20

_5

Element 5 of this Tuple20

_6

Element 6 of this Tuple20

_7

Element 7 of this Tuple20

_8

Element 8 of this Tuple20

_9

Element 9 of this Tuple20

Attributes

Constructor

Create a new tuple with 20 elements. Note that it is more idiomatic to create a Tuple20 via (t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18, t19, t20)

Source
Tuple20.scala
Supertypes
trait Serializable
trait Product20[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: T8 *: T9 *: T10 *: T11 *: T12 *: T13 *: T14 *: T15 *: T16 *: T17 *: T18 *: T19 *: T20 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple21[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15, +T16, +T17, +T18, +T19, +T20, +T21](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7, _8: T8, _9: T9, _10: T10, _11: T11, _12: T12, _13: T13, _14: T14, _15: T15, _16: T16, _17: T17, _18: T18, _19: T19, _20: T20, _21: T21) extends Product21[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21]

A tuple of 21 elements; the canonical representation of a scala.Product21.

A tuple of 21 elements; the canonical representation of a scala.Product21.

Value parameters

_1

Element 1 of this Tuple21

_10

Element 10 of this Tuple21

_11

Element 11 of this Tuple21

_12

Element 12 of this Tuple21

_13

Element 13 of this Tuple21

_14

Element 14 of this Tuple21

_15

Element 15 of this Tuple21

_16

Element 16 of this Tuple21

_17

Element 17 of this Tuple21

_18

Element 18 of this Tuple21

_19

Element 19 of this Tuple21

_2

Element 2 of this Tuple21

_20

Element 20 of this Tuple21

_21

Element 21 of this Tuple21

_3

Element 3 of this Tuple21

_4

Element 4 of this Tuple21

_5

Element 5 of this Tuple21

_6

Element 6 of this Tuple21

_7

Element 7 of this Tuple21

_8

Element 8 of this Tuple21

_9

Element 9 of this Tuple21

Attributes

Constructor

Create a new tuple with 21 elements. Note that it is more idiomatic to create a Tuple21 via (t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18, t19, t20, t21)

Source
Tuple21.scala
Supertypes
trait Serializable
trait Product21[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: T8 *: T9 *: T10 *: T11 *: T12 *: T13 *: T14 *: T15 *: T16 *: T17 *: T18 *: T19 *: T20 *: T21 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple22[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9, +T10, +T11, +T12, +T13, +T14, +T15, +T16, +T17, +T18, +T19, +T20, +T21, +T22](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7, _8: T8, _9: T9, _10: T10, _11: T11, _12: T12, _13: T13, _14: T14, _15: T15, _16: T16, _17: T17, _18: T18, _19: T19, _20: T20, _21: T21, _22: T22) extends Product22[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22]

A tuple of 22 elements; the canonical representation of a scala.Product22.

A tuple of 22 elements; the canonical representation of a scala.Product22.

Value parameters

_1

Element 1 of this Tuple22

_10

Element 10 of this Tuple22

_11

Element 11 of this Tuple22

_12

Element 12 of this Tuple22

_13

Element 13 of this Tuple22

_14

Element 14 of this Tuple22

_15

Element 15 of this Tuple22

_16

Element 16 of this Tuple22

_17

Element 17 of this Tuple22

_18

Element 18 of this Tuple22

_19

Element 19 of this Tuple22

_2

Element 2 of this Tuple22

_20

Element 20 of this Tuple22

_21

Element 21 of this Tuple22

_22

Element 22 of this Tuple22

_3

Element 3 of this Tuple22

_4

Element 4 of this Tuple22

_5

Element 5 of this Tuple22

_6

Element 6 of this Tuple22

_7

Element 7 of this Tuple22

_8

Element 8 of this Tuple22

_9

Element 9 of this Tuple22

Attributes

Constructor

Create a new tuple with 22 elements. Note that it is more idiomatic to create a Tuple22 via (t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18, t19, t20, t21, t22)

Source
Tuple22.scala
Supertypes
trait Serializable
trait Product22[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: T8 *: T9 *: T10 *: T11 *: T12 *: T13 *: T14 *: T15 *: T16 *: T17 *: T18 *: T19 *: T20 *: T21 *: T22 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple3[+T1, +T2, +T3](_1: T1, _2: T2, _3: T3) extends Product3[T1, T2, T3]

A tuple of 3 elements; the canonical representation of a scala.Product3.

A tuple of 3 elements; the canonical representation of a scala.Product3.

Value parameters

_1

Element 1 of this Tuple3

_2

Element 2 of this Tuple3

_3

Element 3 of this Tuple3

Attributes

Constructor

Create a new tuple with 3 elements. Note that it is more idiomatic to create a Tuple3 via (t1, t2, t3)

Source
Tuple3.scala
Supertypes
trait Serializable
trait Product3[T1, T2, T3]
class T1 *: T2 *: T3 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple4[+T1, +T2, +T3, +T4](_1: T1, _2: T2, _3: T3, _4: T4) extends Product4[T1, T2, T3, T4]

A tuple of 4 elements; the canonical representation of a scala.Product4.

A tuple of 4 elements; the canonical representation of a scala.Product4.

Value parameters

_1

Element 1 of this Tuple4

_2

Element 2 of this Tuple4

_3

Element 3 of this Tuple4

_4

Element 4 of this Tuple4

Attributes

Constructor

Create a new tuple with 4 elements. Note that it is more idiomatic to create a Tuple4 via (t1, t2, t3, t4)

Source
Tuple4.scala
Supertypes
trait Serializable
trait Product4[T1, T2, T3, T4]
class T1 *: T2 *: T3 *: T4 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple5[+T1, +T2, +T3, +T4, +T5](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5) extends Product5[T1, T2, T3, T4, T5]

A tuple of 5 elements; the canonical representation of a scala.Product5.

A tuple of 5 elements; the canonical representation of a scala.Product5.

Value parameters

_1

Element 1 of this Tuple5

_2

Element 2 of this Tuple5

_3

Element 3 of this Tuple5

_4

Element 4 of this Tuple5

_5

Element 5 of this Tuple5

Attributes

Constructor

Create a new tuple with 5 elements. Note that it is more idiomatic to create a Tuple5 via (t1, t2, t3, t4, t5)

Source
Tuple5.scala
Supertypes
trait Serializable
trait Product5[T1, T2, T3, T4, T5]
class T1 *: T2 *: T3 *: T4 *: T5 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple6[+T1, +T2, +T3, +T4, +T5, +T6](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6) extends Product6[T1, T2, T3, T4, T5, T6]

A tuple of 6 elements; the canonical representation of a scala.Product6.

A tuple of 6 elements; the canonical representation of a scala.Product6.

Value parameters

_1

Element 1 of this Tuple6

_2

Element 2 of this Tuple6

_3

Element 3 of this Tuple6

_4

Element 4 of this Tuple6

_5

Element 5 of this Tuple6

_6

Element 6 of this Tuple6

Attributes

Constructor

Create a new tuple with 6 elements. Note that it is more idiomatic to create a Tuple6 via (t1, t2, t3, t4, t5, t6)

Source
Tuple6.scala
Supertypes
trait Serializable
trait Product6[T1, T2, T3, T4, T5, T6]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple7[+T1, +T2, +T3, +T4, +T5, +T6, +T7](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7) extends Product7[T1, T2, T3, T4, T5, T6, T7]

A tuple of 7 elements; the canonical representation of a scala.Product7.

A tuple of 7 elements; the canonical representation of a scala.Product7.

Value parameters

_1

Element 1 of this Tuple7

_2

Element 2 of this Tuple7

_3

Element 3 of this Tuple7

_4

Element 4 of this Tuple7

_5

Element 5 of this Tuple7

_6

Element 6 of this Tuple7

_7

Element 7 of this Tuple7

Attributes

Constructor

Create a new tuple with 7 elements. Note that it is more idiomatic to create a Tuple7 via (t1, t2, t3, t4, t5, t6, t7)

Source
Tuple7.scala
Supertypes
trait Serializable
trait Product7[T1, T2, T3, T4, T5, T6, T7]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple8[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7, _8: T8) extends Product8[T1, T2, T3, T4, T5, T6, T7, T8]

A tuple of 8 elements; the canonical representation of a scala.Product8.

A tuple of 8 elements; the canonical representation of a scala.Product8.

Value parameters

_1

Element 1 of this Tuple8

_2

Element 2 of this Tuple8

_3

Element 3 of this Tuple8

_4

Element 4 of this Tuple8

_5

Element 5 of this Tuple8

_6

Element 6 of this Tuple8

_7

Element 7 of this Tuple8

_8

Element 8 of this Tuple8

Attributes

Constructor

Create a new tuple with 8 elements. Note that it is more idiomatic to create a Tuple8 via (t1, t2, t3, t4, t5, t6, t7, t8)

Source
Tuple8.scala
Supertypes
trait Serializable
trait Product8[T1, T2, T3, T4, T5, T6, T7, T8]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: T8 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class Tuple9[+T1, +T2, +T3, +T4, +T5, +T6, +T7, +T8, +T9](_1: T1, _2: T2, _3: T3, _4: T4, _5: T5, _6: T6, _7: T7, _8: T8, _9: T9) extends Product9[T1, T2, T3, T4, T5, T6, T7, T8, T9]

A tuple of 9 elements; the canonical representation of a scala.Product9.

A tuple of 9 elements; the canonical representation of a scala.Product9.

Value parameters

_1

Element 1 of this Tuple9

_2

Element 2 of this Tuple9

_3

Element 3 of this Tuple9

_4

Element 4 of this Tuple9

_5

Element 5 of this Tuple9

_6

Element 6 of this Tuple9

_7

Element 7 of this Tuple9

_8

Element 8 of this Tuple9

_9

Element 9 of this Tuple9

Attributes

Constructor

Create a new tuple with 9 elements. Note that it is more idiomatic to create a Tuple9 via (t1, t2, t3, t4, t5, t6, t7, t8, t9)

Source
Tuple9.scala
Supertypes
trait Serializable
trait Product9[T1, T2, T3, T4, T5, T6, T7, T8, T9]
class T1 *: T2 *: T3 *: T4 *: T5 *: T6 *: T7 *: T8 *: T9 *: EmptyTuple.type
trait Tuple
trait Product
trait Equals
class Object
trait Matchable
class Any
Show all
final case class UninitializedFieldError(msg: String) extends RuntimeException

This class implements errors which are thrown whenever a field is used before it has been initialized.

This class implements errors which are thrown whenever a field is used before it has been initialized.

Such runtime checks are not emitted by default. They can be enabled by the -Xcheckinit compiler option.

Attributes

Source
UninitializedFieldError.scala
Supertypes
trait Product
trait Equals
class Exception
class Throwable
trait Serializable
class Object
trait Matchable
class Any
Show all
final abstract class Unit extends AnyVal

Unit is a subtype of scala.AnyVal.

Unit is a subtype of scala.AnyVal. There is only one value of type Unit, (), and it is not represented by any object in the underlying runtime system. A method with return type Unit is analogous to a Java method which is declared void.

Attributes

Companion
object
Source
Unit.scala
Supertypes
class AnyVal
trait Matchable
class Any
object Unit

Attributes

Companion
class
Source
Unit.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Unit.type
final class ValueOf[T](val value: T) extends AnyVal

ValueOf[T] provides the unique value of the type T where T is a type which has a single inhabitant.

ValueOf[T] provides the unique value of the type T where T is a type which has a single inhabitant. Eligible types are singleton types of the form stablePath.type, Unit and singleton types corresponding to value literals.

The value itself can conveniently be retrieved with Predef#valueOf, which requires a ValueOf to be available in implicit scope.

The compiler provides instances of ValueOf[T] for all eligible types. Typically an instance would be required where a runtime value corresponding to a type level computation is needed.

For example, we might define a type Residue[M <: Int] corresponding to the group of integers modulo M. We could then mandate that residues can be summed only when they are parameterized by the same modulus,

case class Residue[M <: Int](n: Int) extends AnyVal {
 def +(rhs: Residue[M])(implicit m: ValueOf[M]): Residue[M] =
   Residue((this.n + rhs.n) % valueOf[M])
}

val fiveModTen = Residue[10](5)
val nineModTen = Residue[10](9)

fiveModTen + nineModTen    // OK == Residue[10](4)

val fourModEleven = Residue[11](4)

fiveModTen + fourModEleven // compiler error: type mismatch;
                          //   found   : Residue[11]
                          //   required: Residue[10]

Notice that here the modulus is encoded in the type of the values and so does not incur any additional per-value storage cost. When a runtime value of the modulus is required in the implementation of + it is provided at the call site via the implicit argument m of type ValueOf[M].

Attributes

Source
ValueOf.scala
Supertypes
class AnyVal
trait Matchable
class Any
class deprecated(message: String, since: String) extends ConstantAnnotation

An annotation that designates that a definition is deprecated.

An annotation that designates that a definition is deprecated. A deprecation warning is issued upon usage of the annotated definition.

Library authors should state the library's deprecation policy in their documentation to give developers guidance on how long a deprecated definition will be preserved.

Library authors should prepend the name of their library to the version number to help developers distinguish deprecations coming from different libraries:

@deprecated("this method will be removed", "FooLib 12.0")
def oldMethod(x: Int) = ...

The compiler will emit deprecation warnings grouped by library and version:

oldMethod(1)
oldMethod(2)
aDeprecatedMethodFromLibraryBar(3, 4)

// warning: there was one deprecation warning (since BarLib 3.2)
// warning: there were two deprecation warnings (since FooLib 12.0)
// warning: there were three deprecation warnings in total; re-run with -deprecation for details

@deprecated in the Scala language and its standard library

A deprecated element of the Scala language or a definition in the Scala standard library will be preserved at least for the current major version.

This means that an element deprecated in some 2.13.x release will be preserved in all 2.13.x releases, but may be removed in the future. (A deprecated element might be kept longer to ease migration, but developers should not rely on this.)

Value parameters

message

the message to print during compilation if the definition is accessed

since

a string identifying the first version in which the definition was deprecated

Attributes

See also
Source
deprecated.scala
Supertypes
class Annotation
class Object
trait Matchable
class Any
Show all
final class deprecatedInheritance(message: String, since: String) extends ConstantAnnotation

An annotation that designates that inheriting from a class is deprecated.

An annotation that designates that inheriting from a class is deprecated.

This is usually done to warn about a non-final class being made final in a future version. Sub-classing such a class then generates a warning.

No warnings are generated if the subclass is in the same compilation unit.

Library authors should state the library's deprecation policy in their documentation to give developers guidance on when a type annotated with @deprecatedInheritance will be finalized.

Library authors should prepend the name of their library to the version number to help developers distinguish deprecations coming from different libraries:

@deprecatedInheritance("this class will be made final", "FooLib 12.0")
class Foo

val foo = new Foo     // no deprecation warning
class Bar extends Foo
// warning: inheritance from class Foo is deprecated (since FooLib 12.0): this class will be made final
// class Bar extends Foo
//                   ^

Value parameters

message

the message to print during compilation if the class was sub-classed

since

a string identifying the first version in which inheritance was deprecated

Attributes

See also
Source
deprecatedInheritance.scala
Supertypes
class Annotation
class Object
trait Matchable
class Any
Show all
class deprecatedName(name: String, since: String) extends StaticAnnotation

An annotation that designates that the name of a parameter is deprecated.

An annotation that designates that the name of a parameter is deprecated.

Using this name in a named argument generates a deprecation warning.

Library authors should state the library's deprecation policy in their documentation to give developers guidance on how long a deprecated name will be preserved.

Library authors should prepend the name of their library to the version number to help developers distinguish deprecations coming from different libraries:

def inc(x: Int, @deprecatedName("y", "FooLib 12.0") n: Int): Int = x + n
inc(1, y = 2)

will produce the following warning:

warning: the parameter name y is deprecated (since FooLib 12.0): use n instead
inc(1, y = 2)
         ^

Attributes

See also
Source
deprecatedName.scala
Supertypes
class Annotation
class Object
trait Matchable
class Any
class deprecatedOverriding(message: String, since: String) extends ConstantAnnotation

An annotation that designates that overriding a member is deprecated.

An annotation that designates that overriding a member is deprecated.

Overriding such a member in a sub-class then generates a warning.

Library authors should state the library's deprecation policy in their documentation to give developers guidance on when a method annotated with @deprecatedOverriding will be finalized.

Library authors should prepend the name of their library to the version number to help developers distinguish deprecations coming from different libraries:

class Foo {
  @deprecatedOverriding("this method will be made final", "FooLib 12.0")
  def add(x: Int, y: Int) = x + y
}

class Bar extends Foo // no deprecation warning
class Baz extends Foo {
  override def add(x: Int, y: Int) = x - y
}
// warning: overriding method add in class Foo is deprecated (since FooLib 12.0): this method will be made final
// override def add(x: Int, y: Int) = x - y
//              ^

Value parameters

message

the message to print during compilation if the member was overridden

since

a string identifying the first version in which overriding was deprecated

Attributes

See also
Source
deprecatedOverriding.scala
Supertypes
class Annotation
class Object
trait Matchable
class Any
Show all
class inline extends StaticAnnotation

An annotation for methods that the optimizer should inline.

An annotation for methods that the optimizer should inline.

Note that by default, the Scala optimizer is disabled and no callsites are inlined. See -opt:help for information on how to enable the optimizer and inliner.

When inlining is enabled, the inliner will always try to inline methods or callsites annotated @inline (under the condition that inlining from the defining class is allowed, see -opt-inline-from:help). If inlining is not possible, for example because the method is not final, an optimizer warning will be issued. See -opt-warnings:help for details.

Examples:

@inline   final def f1(x: Int) = x
@noinline final def f2(x: Int) = x
         final def f3(x: Int) = x

def t1 = f1(1)              // inlined if possible
def t2 = f2(1)              // not inlined
def t3 = f3(1)              // may be inlined (the inliner heuristics can select the callsite)
def t4 = f1(1): @noinline   // not inlined (override at callsite)
def t5 = f2(1): @inline     // inlined if possible (override at callsite)
def t6 = f3(1): @inline     // inlined if possible
def t7 = f3(1): @noinline   // not inlined
}

Note: parentheses are required when annotating a callsite within a larger expression.

def t1 = f1(1) + f1(1): @noinline   // equivalent to (f1(1) + f1(1)): @noinline
def t2 = f1(1) + (f1(1): @noinline) // the second call to f1 is not inlined

Attributes

Source
inline.scala
Supertypes
class Annotation
class Object
trait Matchable
class Any
object language

The scala.language object controls the language features available to the programmer, as proposed in the SIP-18 document.

The scala.language object controls the language features available to the programmer, as proposed in the SIP-18 document.

Each of these features has to be explicitly imported into the current scope to become available:

import language.postfixOps // or language._
List(1, 2, 3) reverse

The language features are:

Attributes

Source
language.scala
Supertypes
class Object
trait Matchable
class Any
Self type
language.type
object languageFeature

Attributes

Source
languageFeature.scala
Supertypes
class Object
trait Matchable
class Any
Self type
class main extends Annotation

An annotation that designates a main function

An annotation that designates a main function

Attributes

Source
main.scala
Supertypes
class Annotation
class Object
trait Matchable
class Any
class native extends StaticAnnotation

Marker for native methods.

Marker for native methods.

@native def f(x: Int, y: List[Long]): String = ...

A @native method is compiled to the platform's native method, while discarding the method's body (if any). The body will be type checked if present.

A method marked @native must be a member of a class, not a trait (since 2.12).

Attributes

Source
native.scala
Supertypes
class Annotation
class Object
trait Matchable
class Any
final class noinline extends StaticAnnotation

An annotation for methods that the optimizer should not inline.

An annotation for methods that the optimizer should not inline.

Note that by default, the Scala optimizer is disabled and no callsites are inlined. See -opt:help for information how to enable the optimizer and inliner.

When inlining is enabled, the inliner will never inline methods or callsites annotated @noinline.

Examples:

@inline   final def f1(x: Int) = x
@noinline final def f2(x: Int) = x
         final def f3(x: Int) = x

def t1 = f1(1)              // inlined if possible
def t2 = f2(1)              // not inlined
def t3 = f3(1)              // may be inlined (the inliner heuristics can select the callsite)
def t4 = f1(1): @noinline   // not inlined (override at callsite)
def t5 = f2(1): @inline     // inlined if possible (override at callsite)
def t6 = f3(1): @inline     // inlined if possible
def t7 = f3(1): @noinline   // not inlined
}

Note: parentheses are required when annotating a callsite within a larger expression.

def t1 = f1(1) + f1(1): @noinline   // equivalent to (f1(1) + f1(1)): @noinline
def t2 = f1(1) + (f1(1): @noinline) // the second call to f1 is not inlined

Attributes

Source
noinline.scala
Supertypes
class Annotation
class Object
trait Matchable
class Any
final class specialized(group: SpecializedGroup) extends StaticAnnotation

Annotate type parameters on which code should be automatically specialized.

Annotate type parameters on which code should be automatically specialized. For example:

class MyList[@specialized T] ...

Type T can be specialized on a subset of the primitive types by specifying a list of primitive types to specialize at:

class MyList[@specialized(Int, Double, Boolean) T] ..

Attributes

Source
specialized.scala
Supertypes
class Annotation
class Object
trait Matchable
class Any
final class throws[T <: Throwable](cause: String) extends StaticAnnotation

Annotation for specifying the exceptions thrown by a method.

Annotation for specifying the exceptions thrown by a method. For example:

class Reader(fname: String) {
 private val in = new BufferedReader(new FileReader(fname))
 @throws[IOException]("if the file doesn't exist")
 def read() = in.read()
}

Attributes

Source
throws.scala
Supertypes
class Annotation
class Object
trait Matchable
class Any
final class transient extends StaticAnnotation

Attributes

Source
transient.scala
Supertypes
class Annotation
class Object
trait Matchable
class Any
final class unchecked extends Annotation

An annotation to designate that the annotated entity should not be considered for additional compiler checks.

An annotation to designate that the annotated entity should not be considered for additional compiler checks. Specific applications include annotating the subject of a match expression to suppress exhaustiveness and reachability warnings, and annotating a type argument in a match case to suppress unchecked warnings.

Such suppression should be used with caution, without which one may encounter scala.MatchError or java.lang.ClassCastException at runtime. In most cases one can and should address the warning instead of suppressing it.

object Test extends App {
  // This would normally warn "match is not exhaustive"
  // because `None` is not covered.
  def f(x: Option[String]) = (x: @unchecked) match { case Some(y) => y }
  // This would normally warn "type pattern is unchecked"
  // but here will blindly cast the head element to String.
  def g(xs: Any) = xs match { case x: List[String @unchecked] => x.head }
}

Attributes

Source
unchecked.scala
Supertypes
class Annotation
class Object
trait Matchable
class Any
final class volatile extends StaticAnnotation

Attributes

Source
volatile.scala
Supertypes
class Annotation
class Object
trait Matchable
class Any

Deprecated classlikes

trait DelayedInit

Classes and objects (but note, not traits) inheriting the DelayedInit marker trait will have their initialization code rewritten as follows: code becomes delayedInit(code).

Classes and objects (but note, not traits) inheriting the DelayedInit marker trait will have their initialization code rewritten as follows: code becomes delayedInit(code).

Initialization code comprises all statements and all value definitions that are executed during initialization.

Example:

trait Helper extends DelayedInit {
  def delayedInit(body: => Unit) = {
    println("dummy text, printed before initialization of C")
    body // evaluates the initialization code of C
  }
}

class C extends Helper {
  println("this is the initialization code of C")
}

object Test extends App {
  val c = new C
}

Should result in the following being printed:

dummy text, printed before initialization of C
this is the initialization code of C

Attributes

See also

"Delayed Initialization" subsection of the Scala Language Specification (section 5.1)

Deprecated
true
Source
DelayedInit.scala
Supertypes
class Object
trait Matchable
class Any
Known subtypes
trait App
trait Proxy

This class implements a simple proxy that forwards all calls to the public, non-final methods defined in class Any to another object self.

This class implements a simple proxy that forwards all calls to the public, non-final methods defined in class Any to another object self. Those methods are:

def hashCode(): Int
def equals(other: Any): Boolean
def toString(): String

Note: forwarding methods in this way will most likely create an asymmetric equals method, which is not generally recommended.

Attributes

Companion
object
Deprecated
true
Source
Proxy.scala
Supertypes
class Any
Known subtypes
trait ReferenceWrapper[T]
class PhantomReference[T]
class SoftReference[T]
class WeakReference[T]
trait Typed[T]
trait OrderedProxy[T]
class RichBoolean
trait ScalaNumberProxy[T]
trait FractionalProxy[T]
class RichDouble
class RichFloat
class RichInt
trait IntegralProxy[T]
class RichChar
class RichLong
class RichByte
class RichShort
trait RangedProxy[T]
Show all
object Proxy

Attributes

Companion
trait
Deprecated
true
Source
Proxy.scala
Supertypes
class Object
trait Matchable
class Any
Self type
Proxy.type
final class UninitializedError extends RuntimeException

This class represents uninitialized variable/value errors.

This class represents uninitialized variable/value errors.

Attributes

Deprecated
[Since version 2.12.7]
Source
UninitializedError.scala
Supertypes
class Exception
class Throwable
trait Serializable
class Object
trait Matchable
class Any
Show all

Experimental classlikes

erased class CanThrow[-E <: Exception]

A capability class that allows to throw exception E. When used with the experimental.saferExceptions feature, a throw Ex() expression will require a given of class CanThrow[Ex] to be available.

A capability class that allows to throw exception E. When used with the experimental.saferExceptions feature, a throw Ex() expression will require a given of class CanThrow[Ex] to be available.

Attributes

Experimental
true
Source
CanThrow.scala
Supertypes
class Object
trait Matchable
class Any
object caps

Attributes

Experimental
true
Source
caps.scala
Supertypes
class Object
trait Matchable
class Any
Self type
caps.type
object unsafeExceptions

Attributes

Experimental
true
Source
CanThrow.scala
Supertypes
class Object
trait Matchable
class Any
Self type

Types

type & = [X0, X1] =>> X0 & X1

The intersection of two types.

Attributes

type ::[+A] = ::[A]

Attributes

Source
package.scala
type BigDecimal = BigDecimal

Attributes

Source
package.scala
type BigInt = BigInt

Attributes

Source
package.scala
type Cloneable = Cloneable

Attributes

Source
package.scala
type Either[+A, +B] = Either[A, B]

Attributes

Source
package.scala
type EmptyTuple = EmptyTuple.type

A tuple of 0 elements

A tuple of 0 elements

Attributes

Source
Tuple.scala
type Equiv[T] = Equiv[T]

Attributes

Source
package.scala
type Error = Error

Attributes

Source
package.scala
type Exception = Exception

Attributes

Source
package.scala
type Fractional[T] = Fractional[T]

Attributes

Source
package.scala
opaque type IArray[+T]

Attributes

Source
IArray.scala
type IndexedSeq[+A] = IndexedSeq[A]

Attributes

Source
package.scala
type Integral[T] = Integral[T]

Attributes

Source
package.scala
type Iterable[+A] = Iterable[A]

Attributes

Source
package.scala
type IterableOnce[+A] = IterableOnce[A]

Attributes

Source
package.scala
type Iterator[+A] = Iterator[A]

Attributes

Source
package.scala
type LazyList[+A] = LazyList[A]

Attributes

Source
package.scala
type Left[+A, +B] = Left[A, B]

Attributes

Source
package.scala
type List[+A] = List[A]

Attributes

Source
package.scala
type Numeric[T] = Numeric[T]

Attributes

Source
package.scala
type Ordered[T] = Ordered[T]

Attributes

Source
package.scala
type Ordering[T] = Ordering[T]

Attributes

Source
package.scala
type PartialOrdering[T] = PartialOrdering[T]

Attributes

Source
package.scala
type PartiallyOrdered[T] = PartiallyOrdered[T]

Attributes

Source
package.scala
type Range = Range

Attributes

Source
package.scala
type Right[+A, +B] = Right[A, B]

Attributes

Source
package.scala
type Seq[+A] = Seq[A]

Attributes

Source
package.scala
type Serializable = Serializable

Attributes

Source
package.scala
type StringBuilder = StringBuilder

Attributes

Source
package.scala
type Throwable = Throwable

Attributes

Source
package.scala
type Vector[+A] = Vector[A]

Attributes

Source
package.scala
type | = [X0, X1] =>> X0 | X1

The union of two types.

Attributes

Deprecated types

type BufferedIterator[+A] = BufferedIterator[A]

Attributes

Deprecated
true
Source
package.scala
type Stream[+A] = Stream[A]

Attributes

Deprecated
true
Source
package.scala
type Traversable[+A] = Iterable[A]

Attributes

Deprecated
true
Source
package.scala
type TraversableOnce[+A] = IterableOnce[A]

Attributes

Deprecated
true
Source
package.scala

Value members

Concrete fields

val +:: +:.type

Attributes

Source
package.scala
val :+: :+.type

Attributes

Source
package.scala
val ::: ::.type

Attributes

Source
package.scala
val AnyRef: Specializable

Attributes

Source
package.scala
val BigDecimal: BigDecimal.type

Attributes

Source
package.scala
val BigInt: BigInt.type

Attributes

Source
package.scala
val Either: Either.type

Attributes

Source
package.scala
val Equiv: Equiv.type

Attributes

Source
package.scala
val Fractional: Fractional.type

Attributes

Source
package.scala
val IndexedSeq: IndexedSeq.type

Attributes

Source
package.scala
val Integral: Integral.type

Attributes

Source
package.scala
val Iterable: Iterable.type

Attributes

Source
package.scala
val Iterator: Iterator.type

Attributes

Source
package.scala
val LazyList: LazyList.type

Attributes

Source
package.scala
val Left: Left.type

Attributes

Source
package.scala
val List: List.type

Attributes

Source
package.scala
val Nil: Nil.type

Attributes

Source
package.scala
val Numeric: Numeric.type

Attributes

Source
package.scala
val Ordered: Ordered.type

Attributes

Source
package.scala
val Ordering: Ordering.type

Attributes

Source
package.scala
val Range: Range.type

Attributes

Source
package.scala
val Right: Right.type

Attributes

Source
package.scala
val Seq: Seq.type

Attributes

Source
package.scala
val StringBuilder: StringBuilder.type

Attributes

Source
package.scala
val Vector: Vector.type

Attributes

Source
package.scala

Deprecated fields

val Stream: Stream.type

Attributes

Deprecated
true
Source
package.scala
val Traversable: Iterable.type

Attributes

Deprecated
true
Source
package.scala
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