Scala Standard Library2.12.5 < Back
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# 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 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.

  Definition Classes
    scala
  See also

    java.lang.Math

- BigDecimal
- BigInt
- Equiv
- Fractional
- Integral
- LowPriorityEquiv
- LowPriorityOrderingImplicits
- Numeric
- Ordered
- Ordering
- PartialOrdering
- PartiallyOrdered
- ScalaNumericAnyConversions
- ScalaNumericConversions

t

scala.math

# Equiv 

###
Companion object Equiv

#### trait Equiv[T] extends Serializable

A trait for representing equivalence relations. It is important to distinguish between a type that can be compared for equality or equivalence and a representation of equivalence on some type. This trait is for representing the latter.

An equivalence relation is a binary relation on a type. This relation is exposed as the `equiv` method of the `Equiv` trait. The relation must be:

1. reflexive: `equiv(x, x) == true` for any x of type `T`.
2. symmetric: `equiv(x, y) == equiv(y, x)` for any `x` and `y` of type `T`.
3. transitive: if `equiv(x, y) == true` and `equiv(y, z) == true`, then `equiv(x, z) == true` for any `x`, `y`, and `z` of type `T`.

Source
  Equiv.scala
Version

  1.0, 2008-04-03

Since

  2.7

Linear Supertypes
Serializable, java.io.Serializable, Any
Known Subclasses
ValueOrdering, DeadlineIsOrdered, DurationIsOrdered, FiniteDurationIsOrdered, Fractional, Integral, Numeric, BigDecimalAsIfIntegral, BigDecimalAsIfIntegral, BigDecimalIsConflicted, BigDecimalIsFractional, BigDecimalIsFractional, BigIntIsIntegral, BigIntIsIntegral, ByteIsIntegral, ByteIsIntegral, CharIsIntegral, CharIsIntegral, DoubleAsIfIntegral, DoubleAsIfIntegral, DoubleIsConflicted, DoubleIsFractional, DoubleIsFractional, FloatAsIfIntegral, FloatAsIfIntegral, FloatIsConflicted, FloatIsFractional, FloatIsFractional, IntIsIntegral, IntIsIntegral, LongIsIntegral, LongIsIntegral, ShortIsIntegral, ShortIsIntegral, Ordering, BigDecimal, BigDecimalOrdering, BigInt, BigIntOrdering, Boolean, BooleanOrdering, Byte, ByteOrdering, Char, CharOrdering, Double, DoubleOrdering, Float, FloatOrdering, Int, IntOrdering, Long, LongOrdering, OptionOrdering, Short, ShortOrdering, String, StringOrdering, Unit, UnitOrdering, PartialOrdering
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Ordering

1. Alphabetic
2. By Inheritance

Inherited

1. Equiv
2. Serializable
3. Serializable
4. Any

Implicitly

1. by any2stringadd
2. by StringFormat
3. by Ensuring
4. by ArrowAssoc

1. Hide All
2. Show All

Visibility

1. Public
2. All

### Abstract Value Members

1.  abstract def equiv(x: T, y: T): Boolean

   Returns `true` iff `x` is equivalent to `y`.

2.  abstract def getClass(): Class[_]

   Returns the runtime class representation of the object.

   Returns the runtime class representation of the object.

   returns

     a class object corresponding to the runtime type of the receiver.

   Definition Classes
     Any

### Concrete Value Members

1.  final def !=(arg0: Any): Boolean

   Test two objects for inequality.

   Test two objects for inequality.

   returns

     `true` if !(this == that), false otherwise.

   Definition Classes
     Any
2.  final def ##(): Int

   Equivalent to `x.hashCode` except for boxed numeric types and `null`.

   Equivalent to `x.hashCode` except for boxed numeric types and `null`. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For `null` returns a hashcode where `null.hashCode` throws a `NullPointerException`.

   returns

     a hash value consistent with ==

   Definition Classes
     Any
3.  def +(other: String): String
   Implicit
     This member is added by an implicit conversion from Equiv[T] to any2stringadd[Equiv[T]] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd
4.  def ->[B](y: B): (Equiv[T], B)
   Implicit
     This member is added by an implicit conversion from Equiv[T] to ArrowAssoc[Equiv[T]] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @inline()
5.  final def ==(arg0: Any): Boolean

   Test two objects for equality.

   Test two objects for equality. The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

   returns

     `true` if the receiver object is equivalent to the argument; `false` otherwise.

   Definition Classes
     Any
6.  final def asInstanceOf[T0]: T0

   Cast the receiver object to be of type `T0`.

   Cast the receiver object to be of type `T0`.

   Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression `1.asInstanceOf[String]` will throw a `ClassCastException` at runtime, while the expression `List(1).asInstanceOf[List[String]]` will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

   returns

     the receiver object.

   Definition Classes
     Any
   Exceptions thrown

     `ClassCastException` if the receiver object is not an instance of the erasure of type `T0`.

7.  def ensuring(cond: (Equiv[T]) ⇒ Boolean, msg: ⇒ Any): Equiv[T]
   Implicit
     This member is added by an implicit conversion from Equiv[T] to Ensuring[Equiv[T]] performed by method Ensuring in scala.Predef.
   Definition Classes
     Ensuring
8.  def ensuring(cond: (Equiv[T]) ⇒ Boolean): Equiv[T]
   Implicit
     This member is added by an implicit conversion from Equiv[T] to Ensuring[Equiv[T]] performed by method Ensuring in scala.Predef.
   Definition Classes
     Ensuring
9.  def ensuring(cond: Boolean, msg: ⇒ Any): Equiv[T]
   Implicit
     This member is added by an implicit conversion from Equiv[T] to Ensuring[Equiv[T]] performed by method Ensuring in scala.Predef.
   Definition Classes
     Ensuring
10.  def ensuring(cond: Boolean): Equiv[T]
    Implicit
      This member is added by an implicit conversion from Equiv[T] to Ensuring[Equiv[T]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
11.  def equals(arg0: Any): Boolean

    Compares the receiver object (`this`) with the argument object (`that`) for equivalence.

    Compares the receiver object (`this`) with the argument object (`that`) for equivalence.

    Any implementation of this method should be an equivalence relation:

    - It is reflexive: for any instance `x` of type `Any`, `x.equals(x)` should return `true`.
    - It is symmetric: for any instances `x` and `y` of type `Any`, `x.equals(y)` should return `true` if and only if `y.equals(x)` returns `true`.
    - It is transitive: for any instances `x`, `y`, and `z` of type `Any` if `x.equals(y)` returns `true` and `y.equals(z)` returns `true`, then `x.equals(z)` should return `true`.

    If you override this method, you should verify that your implementation remains an equivalence relation. Additionally, when overriding this method it is usually necessary to override `hashCode` to ensure that objects which are "equal" (`o1.equals(o2)` returns `true`) hash to the same scala.Int. (`o1.hashCode.equals(o2.hashCode)`).

    returns

      `true` if the receiver object is equivalent to the argument; `false` otherwise.

    Definition Classes
      Any
12.  def formatted(fmtstr: String): String

    Returns string formatted according to given `format` string.

    Returns string formatted according to given `format` string. Format strings are as for `String.format` (@see java.lang.String.format).

    Implicit
      This member is added by an implicit conversion from Equiv[T] to StringFormat[Equiv[T]] performed by method StringFormat in scala.Predef.
    Definition Classes
      StringFormat
    Annotations
      @inline()
13.  def hashCode(): Int

    Calculate a hash code value for the object.

    Calculate a hash code value for the object.

    The default hashing algorithm is platform dependent.

    Note that it is allowed for two objects to have identical hash codes (`o1.hashCode.equals(o2.hashCode)`) yet not be equal (`o1.equals(o2)` returns `false`). A degenerate implementation could always return `0`. However, it is required that if two objects are equal (`o1.equals(o2)` returns `true`) that they have identical hash codes (`o1.hashCode.equals(o2.hashCode)`). Therefore, when overriding this method, be sure to verify that the behavior is consistent with the `equals` method.

    returns

      the hash code value for this object.

    Definition Classes
      Any
14.  final def isInstanceOf[T0]: Boolean

    Test whether the dynamic type of the receiver object is `T0`.

    Test whether the dynamic type of the receiver object is `T0`.

    Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression `1.isInstanceOf[String]` will return `false`, while the expression `List(1).isInstanceOf[List[String]]` will return `true`. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

    returns

      `true` if the receiver object is an instance of erasure of type `T0`; `false` otherwise.

    Definition Classes
      Any
15.  def toString(): String

    Returns a string representation of the object.

    Returns a string representation of the object.

    The default representation is platform dependent.

    returns

      a string representation of the object.

    Definition Classes
      Any
16.  def →[B](y: B): (Equiv[T], B)
    Implicit
      This member is added by an implicit conversion from Equiv[T] to ArrowAssoc[Equiv[T]] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
      ArrowAssoc

### Inherited from Serializable

### Inherited from java.io.Serializable

### Inherited from Any

### Inherited by implicit conversion any2stringadd from Equiv[T] to any2stringadd[Equiv[T]]

### Inherited by implicit conversion StringFormat from Equiv[T] to StringFormat[Equiv[T]]

### Inherited by implicit conversion Ensuring from Equiv[T] to Ensuring[Equiv[T]]

### Inherited by implicit conversion ArrowAssoc from Equiv[T] to ArrowAssoc[Equiv[T]]

### Ungrouped