Scala 3

Scala 3/scala/AnyVal

AnyVal

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. 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:

The subrange types are scala.Byte, scala.Short, and scala.Char.
The integer types include the subrange types as well as scala.Int and scala.Long.
The floating point types are scala.Float and scala.Double.

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.

trait Matchable

class Any

class Addr

class UnapplySeqWrapper[T]

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 ArrayOps[A]

class IterableOnceExtensionMethods[A]

class SizeCompareOps

class SearchImpl[Repr, A]

class UnapplySeqWrapper[A]

class Shape

class StringOps

class Deferrer[A]

class Partial[T, U]

class Deferrer[A]

class DoubleMult

class DurationDouble

class DurationInt

class DurationLong

class JavaDurationOps

class ScalaDurationOps

class RichBiConsumerAsFunction2[T, U]

class RichBiFunctionAsFunction2[T, U, R]

class RichBiPredicateAsFunction2[T, U]

class RichBinaryOperatorAsFunction2[T]

class RichBooleanSupplierAsFunction0

class RichConsumerAsFunction1[T]

class RichDoubleBinaryOperatorAsFunction2

class RichDoubleConsumerAsFunction1

class RichDoubleFunctionAsFunction1[R]

class RichDoublePredicateAsFunction1

class RichDoubleSupplierAsFunction0

class RichDoubleToIntFunctionAsFunction1

class RichDoubleToLongFunctionAsFunction1

class RichDoubleUnaryOperatorAsFunction1

class RichFunction0AsBooleanSupplier

class RichFunction0AsDoubleSupplier

class RichFunction0AsIntSupplier

class RichFunction0AsLongSupplier

class RichFunction0AsSupplier[T]

class RichFunction1AsConsumer[T]

class RichFunction1AsDoubleConsumer

class RichFunction1AsDoubleFunction[R]

class RichFunction1AsDoublePredicate

class RichFunction1AsDoubleToIntFunction

class RichFunction1AsDoubleToLongFunction

class RichFunction1AsDoubleUnaryOperator

class RichFunction1AsFunction[T, R]

class RichFunction1AsIntConsumer

class RichFunction1AsIntFunction[R]

class RichFunction1AsIntPredicate

class RichFunction1AsIntToDoubleFunction

class RichFunction1AsIntToLongFunction

class RichFunction1AsIntUnaryOperator

class RichFunction1AsLongConsumer

class RichFunction1AsLongFunction[R]

class RichFunction1AsLongPredicate

class RichFunction1AsLongToDoubleFunction

class RichFunction1AsLongToIntFunction

class RichFunction1AsLongUnaryOperator

class RichFunction1AsPredicate[T]

class RichFunction1AsToDoubleFunction[T]

class RichFunction1AsToIntFunction[T]

class RichFunction1AsToLongFunction[T]

class RichFunction1AsUnaryOperator[T]

class RichFunction2AsBiConsumer[T, U]

class RichFunction2AsBiFunction[T, U, R]

class RichFunction2AsBiPredicate[T, U]

class RichFunction2AsBinaryOperator[T]

class RichFunction2AsDoubleBinaryOperator

class RichFunction2AsIntBinaryOperator

class RichFunction2AsLongBinaryOperator

class RichFunction2AsObjDoubleConsumer[T]

class RichFunction2AsObjIntConsumer[T]

class RichFunction2AsObjLongConsumer[T]

class RichFunction2AsToDoubleBiFunction[T, U]

class RichFunction2AsToIntBiFunction[T, U]

class RichFunction2AsToLongBiFunction[T, U]

class RichFunctionAsFunction1[T, R]

class RichIntBinaryOperatorAsFunction2

class RichIntConsumerAsFunction1

class RichIntFunctionAsFunction1[R]

class RichIntPredicateAsFunction1

class RichIntSupplierAsFunction0

class RichIntToDoubleFunctionAsFunction1

class RichIntToLongFunctionAsFunction1

class RichIntUnaryOperatorAsFunction1

class RichLongBinaryOperatorAsFunction2

class RichLongConsumerAsFunction1

class RichLongFunctionAsFunction1[R]

class RichLongPredicateAsFunction1

class RichLongSupplierAsFunction0

class RichLongToDoubleFunctionAsFunction1

class RichLongToIntFunctionAsFunction1

class RichLongUnaryOperatorAsFunction1

class RichObjDoubleConsumerAsFunction2[T]

class RichObjIntConsumerAsFunction2[T]

class RichObjLongConsumerAsFunction2[T]

class RichPredicateAsFunction1[T]

class RichSupplierAsFunction0[T]

class RichToDoubleBiFunctionAsFunction2[T, U]

class RichToDoubleFunctionAsFunction1[T]

class RichToIntBiFunctionAsFunction2[T, U]

class RichToIntFunctionAsFunction1[T]

class RichToLongBiFunctionAsFunction2[T, U]

class RichToLongFunctionAsFunction1[T]

class RichUnaryOperatorAsFunction1[T]

class CompletionStageOps[T]

class FutureOps[T]

class RichOption[A]

class RichOptional[A]

class RichOptionalDouble

class RichOptionalInt

class RichOptionalLong

class RichBoolean

class RichDouble

class RichFloat

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]