Packages

•  package root

  This is the documentation for the Scala standard library.

  This is the documentation for the Scala standard library.

  Package structure

  The scala package contains core types like Int, Float, Array or Option which are accessible in all Scala compilation units without explicit qualification or imports.

  Notable packages include:

  • scala.collection and its sub-packages contain Scala's collections framework
    • scala.collection.immutable - Immutable, sequential data-structures such as Vector, List, Range, HashMap or HashSet
    • scala.collection.mutable - Mutable, sequential data-structures such as ArrayBuffer, StringBuilder, HashMap or HashSet
    • scala.collection.concurrent - Mutable, concurrent data-structures such as TrieMap
    • scala.collection.parallel.immutable - Immutable, parallel data-structures such as ParVector, ParRange, ParHashMap or ParHashSet
    • scala.collection.parallel.mutable - Mutable, parallel data-structures such as ParArray, ParHashMap, ParTrieMap or ParHashSet
  • scala.concurrent - Primitives for concurrent programming such as Futures and Promises
  • scala.io - Input and output operations
  • scala.math - Basic math functions and additional numeric types like BigInt and BigDecimal
  • scala.sys - Interaction with other processes and the operating system
  • scala.util.matching - Regular expressions

  Other packages exist. See the complete list on the right.

  Additional parts of the standard library are shipped as separate libraries. These include:

  • scala.reflect - Scala's reflection API (scala-reflect.jar)
  • scala.xml - XML parsing, manipulation, and serialization (scala-xml.jar)
  • scala.swing - A convenient wrapper around Java's GUI framework called Swing (scala-swing.jar)
  • scala.util.parsing - Parser combinators (scala-parser-combinators.jar)

  Automatic imports

  Identifiers in the scala package and the scala.Predef object are always in scope by default.

  Some of these identifiers are type aliases provided as shortcuts to commonly used classes. For example, List is an alias for scala.collection.immutable.List.

  Other aliases refer to classes provided by the underlying platform. For example, on the JVM, String is an alias for java.lang.String.

  Definition Classes

  root

•  package scala

  Core Scala types.

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

  Definition Classes

  root

•  abstract class Enumeration 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 evaluation.

  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.

  Definition Classes

  scala

  Annotations

  @SerialVersionUID()

  Examples:

  1. // 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

  ,

  2. // 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
       }
       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)

• Val
• Value
• ValueOrdering
• ValueSet

scala.Enumeration

Val 