Scala 3

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.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.collection.parallel` - Parallel collections (scala-parallel-collections.jar)
• `scala.util.parsing` - Parser combinators (scala-parser-combinators.jar)
• `scala.swing` - A convenient wrapper around Java's GUI framework called Swing (scala-swing.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.