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

•  package util

  Definition Classes

  scala

•  package control

  Definition Classes

  util

•  object TailCalls

  Methods exported by this object implement tail calls via trampolining.

  Methods exported by this object implement tail calls via trampolining. Tail calling methods have to return their result using done or call the next method using tailcall. Both return a TailRec object. The result of evaluating a tailcalling function can be retrieved from a Tailrec value using method result. Implemented as described in "Stackless Scala with Free Monads" http://blog.higher-order.com/assets/trampolines.pdf

  Here's a usage example:

  import scala.util.control.TailCalls._
  
  def isEven(xs: List[Int]): TailRec[Boolean] =
    if (xs.isEmpty) done(true) else tailcall(isOdd(xs.tail))
  
  def isOdd(xs: List[Int]): TailRec[Boolean] =
   if (xs.isEmpty) done(false) else tailcall(isEven(xs.tail))
  
  isEven((1 to 100000).toList).result
  
  def fib(n: Int): TailRec[Int] =
    if (n < 2) done(n) else for {
      x <- tailcall(fib(n - 1))
      y <- tailcall(fib(n - 2))
    } yield (x + y)
  
  fib(40).result

  Definition Classes

  control

• Call
• Cont
• Done
• TailRec

scala.util.control.TailCalls

TailRec 