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:

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

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

    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

  • object Ordering extends LowPriorityOrderingImplicits with java.io.Serializable

    This is the companion object for the scala.math.Ordering trait.

    This is the companion object for the scala.math.Ordering trait.

    It contains many implicit orderings as well as well as methods to construct new orderings.

    Definition Classes
    math
  • object Double

    Orderings for Doubles.

    Orderings for Doubles.

    The behavior of the comparison operations provided by the default (implicit) ordering on Double changed in 2.10.0 and 2.13.0. Prior to Scala 2.10.0, the Ordering instance used semantics consistent with java.lang.Double.compare.

    Scala 2.10.0 changed the implementation of lt, equiv, min, etc., to be IEEE 754 compliant, while keeping the compare method NOT compliant, creating an internally inconsistent instance. IEEE 754 specifies that 0.0 == -0.0. In addition, it requires all comparisons with Double.NaN return false thus 0.0 < Double.NaN, 0.0 > Double.NaN, and Double.NaN == Double.NaN all yield false, analogous None in flatMap.

    Recognizing the limitation of the IEEE 754 semantics in terms of ordering, Scala 2.13.0 created two instances: Ordering.Double.IeeeOrdering, which retains the IEEE 754 semantics from Scala 2.12.x, and Ordering.Double.TotalOrdering, which brings back the java.lang.Double.compare semantics for all operations. The default extends TotalOrdering.

    List(0.0, 1.0, 0.0 / 0.0, -1.0 / 0.0).sorted      // List(-Infinity, 0.0, 1.0, NaN)
List(0.0, 1.0, 0.0 / 0.0, -1.0 / 0.0).min         // -Infinity
implicitly[Ordering[Double]].lt(0.0, 0.0 / 0.0)   // true
{
  import Ordering.Double.IeeeOrdering
  List(0.0, 1.0, 0.0 / 0.0, -1.0 / 0.0).sorted    // List(-Infinity, 0.0, 1.0, NaN)
  List(0.0, 1.0, 0.0 / 0.0, -1.0 / 0.0).min       // NaN
  implicitly[Ordering[Double]].lt(0.0, 0.0 / 0.0) // false
}
    Definition Classes
    Ordering
  • IeeeOrdering
  • TotalOrdering

trait IeeeOrdering extends Ordering[Double]

An ordering for Doubles which is consistent with IEEE specifications whenever possible.

  • lt, lteq, equiv, gteq and gt are consistent with primitive comparison operations for Doubles, and return false when called with NaN.
  • min and max are consistent with math.min and math.max, and return NaN when called with NaN as either argument.
  • compare behaves the same as java.lang.Double.compare.

Because the behavior of Doubles specified by IEEE is not consistent with a total ordering when dealing with NaN, there are two orderings defined for Double: TotalOrdering, which is consistent with a total ordering, and IeeeOrdering, which is consistent as much as possible with IEEE spec and floating point operations defined in scala.math.

This ordering may be preferable for numeric contexts.

Source
Ordering.scala
See also

TotalOrdering

Linear Supertypes
Ordering[Double], PartialOrdering[Double], Equiv[Double], java.io.Serializable, Comparator[Double], AnyRef, Any
Known Subclasses
DoubleIsFractional, IeeeOrdering
Type Hierarchy
Ordering
  1. Alphabetic
  2. By Inheritance
Inherited
  1. IeeeOrdering
  2. Ordering
  3. PartialOrdering
  4. Equiv
  5. Serializable
  6. Comparator
  7. AnyRef
  8. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
  1. Hide All
  2. Show All
Visibility
  1. Public
  2. Protected

Type Members

  1. class OrderingOps extends AnyRef

    This inner class defines comparison operators available for T.

    This inner class defines comparison operators available for T.

    It can't extend AnyVal because it is not a top-level class or a member of a statically accessible object.

    Definition Classes
    Ordering

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
    AnyRef → 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
    AnyRef → Any
  3. def +(other: String): String
    Implicit
    This member is added by an implicit conversion from IeeeOrdering toany2stringadd[IeeeOrdering] performed by method any2stringadd in scala.Predef.
    Definition Classes
    any2stringadd
  4. def ->[B](y: B): (IeeeOrdering, B)
    Implicit
    This member is added by an implicit conversion from IeeeOrdering toArrowAssoc[IeeeOrdering] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @inline()
  5. final def ==(arg0: Any): Boolean

    The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).

    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
    AnyRef → 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 clone(): AnyRef

    Create a copy of the receiver object.

    Create a copy of the receiver object.

    The default implementation of the clone method is platform dependent.

    returns

    a copy of the receiver object.

    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.CloneNotSupportedException]) @native()
    Note

    not specified by SLS as a member of AnyRef

  8. def compare(x: Double, y: Double): Int

    Returns an integer whose sign communicates how x compares to y.

    Returns an integer whose sign communicates how x compares to y.

    The result sign has the following meaning:

    • negative if x < y
    • positive if x > y
    • zero otherwise (if x == y)
    Definition Classes
    IeeeOrdering → Ordering → Comparator
  9. def ensuring(cond: (IeeeOrdering) => Boolean, msg: => Any): IeeeOrdering
    Implicit
    This member is added by an implicit conversion from IeeeOrdering toEnsuring[IeeeOrdering] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  10. def ensuring(cond: (IeeeOrdering) => Boolean): IeeeOrdering
    Implicit
    This member is added by an implicit conversion from IeeeOrdering toEnsuring[IeeeOrdering] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  11. def ensuring(cond: Boolean, msg: => Any): IeeeOrdering
    Implicit
    This member is added by an implicit conversion from IeeeOrdering toEnsuring[IeeeOrdering] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  12. def ensuring(cond: Boolean): IeeeOrdering
    Implicit
    This member is added by an implicit conversion from IeeeOrdering toEnsuring[IeeeOrdering] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  13. final def eq(arg0: AnyRef): Boolean

    Tests whether the argument (that) is a reference to the receiver object (this).

    Tests whether the argument (that) is a reference to the receiver object (this).

    The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional properties:

    • It is consistent: for any non-null instances x and y of type AnyRef, multiple invocations of x.eq(y) consistently returns true or consistently returns false.
    • For any non-null instance x of type AnyRef, x.eq(null) and null.eq(x) returns false.
    • null.eq(null) returns true.

    When overriding the equals or hashCode methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).

    returns

    true if the argument is a reference to the receiver object; false otherwise.

    Definition Classes
    AnyRef
  14. def equals(arg0: AnyRef): Boolean

    The equality method for reference types.

    The equality method for reference types. Default implementation delegates to eq.

    See also equals in scala.Any.

    returns

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

    Definition Classes
    AnyRef → Any
  15. def equiv(x: Double, y: Double): Boolean

    Return true if x == y in the ordering.

    Return true if x == y in the ordering.

    Definition Classes
    IeeeOrdering → Ordering → PartialOrdering → Equiv
  16. def finalize(): Unit

    Called by the garbage collector on the receiver object when there are no more references to the object.

    Called by the garbage collector on the receiver object when there are no more references to the object.

    The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.

    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.Throwable])
    Note

    not specified by SLS as a member of AnyRef

  17. 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 IeeeOrdering toStringFormat[IeeeOrdering] performed by method StringFormat in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @inline()
  18. final def getClass(): Class[_ <: AnyRef]

    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
    AnyRef → Any
    Annotations
    @native()
  19. def gt(x: Double, y: Double): Boolean

    Return true if x > y in the ordering.

    Return true if x > y in the ordering.

    Definition Classes
    IeeeOrdering → Ordering → PartialOrdering
  20. def gteq(x: Double, y: Double): Boolean

    Return true if x >= y in the ordering.

    Return true if x >= y in the ordering.

    Definition Classes
    IeeeOrdering → Ordering → PartialOrdering
  21. def hashCode(): Int

    The hashCode method for reference types.

    The hashCode method for reference types. See hashCode in scala.Any.

    returns

    the hash code value for this object.

    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  22. 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
  23. def isReverseOf(other: Ordering[_]): Boolean

    Returns whether or not the other ordering is the opposite ordering of this one.

    Returns whether or not the other ordering is the opposite ordering of this one.

    Equivalent to other == this.reverse.

    Implementations should only override this method if they are overriding reverse as well.

    Definition Classes
    Ordering
  24. def lt(x: Double, y: Double): Boolean

    Return true if x < y in the ordering.

    Return true if x < y in the ordering.

    Definition Classes
    IeeeOrdering → Ordering → PartialOrdering
  25. def lteq(x: Double, y: Double): Boolean

    Return true if x <= y in the ordering.

    Return true if x <= y in the ordering.

    Definition Classes
    IeeeOrdering → Ordering → PartialOrdering
  26. def max[U <: Double](x: U, y: U): U

    Return x if x >= y, otherwise y.

    Return x if x >= y, otherwise y.

    Definition Classes
    IeeeOrdering → Ordering
  27. def min[U <: Double](x: U, y: U): U

    Return x if x <= y, otherwise y.

    Return x if x <= y, otherwise y.

    Definition Classes
    IeeeOrdering → Ordering
  28. implicit def mkOrderingOps(lhs: Double): OrderingOps

    This implicit method augments T with the comparison operators defined in scala.math.Ordering.Ops.

    This implicit method augments T with the comparison operators defined in scala.math.Ordering.Ops.

    Definition Classes
    Ordering
  29. final def ne(arg0: AnyRef): Boolean

    Equivalent to !(this eq that).

    Equivalent to !(this eq that).

    returns

    true if the argument is not a reference to the receiver object; false otherwise.

    Definition Classes
    AnyRef
  30. final def notify(): Unit

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Definition Classes
    AnyRef
    Annotations
    @native()
    Note

    not specified by SLS as a member of AnyRef

  31. final def notifyAll(): Unit

    Wakes up all threads that are waiting on the receiver object's monitor.

    Wakes up all threads that are waiting on the receiver object's monitor.

    Definition Classes
    AnyRef
    Annotations
    @native()
    Note

    not specified by SLS as a member of AnyRef

  32. def on[U](f: (U) => Double): Ordering[U]

    Given f, a function from U into T, creates an Ordering[U] whose compare function is equivalent to:

    Given f, a function from U into T, creates an Ordering[U] whose compare function is equivalent to:

    def compare(x:U, y:U) = Ordering[T].compare(f(x), f(y))
    Definition Classes
    Ordering
  33. def orElse(other: Ordering[Double]): Ordering[Double]

    Creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else the result of others compare function.

    Creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else the result of others compare function.

    other

    an Ordering to use if this Ordering returns zero

    Definition Classes
    Ordering
    Example:

    1. case class Pair(a: Int, b: Int)

val pairOrdering = Ordering.by[Pair, Int](_.a)
                           .orElse(Ordering.by[Pair, Int](_.b))
  34. def orElseBy[S](f: (Double) => S)(implicit ord: Ordering[S]): Ordering[Double]

    Given f, a function from T into S, creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else a result equivalent to:

    Given f, a function from T into S, creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else a result equivalent to:

    Ordering[S].compare(f(x), f(y))

    This function is equivalent to passing the result of Ordering.by(f) to orElse.

    Definition Classes
    Ordering
    Example:

    1. case class Pair(a: Int, b: Int)

val pairOrdering = Ordering.by[Pair, Int](_.a)
                           .orElseBy[Int](_.b)
  35. def reverse: Ordering[Double]

    Return the opposite ordering of this one.

    Return the opposite ordering of this one.

    Implementations overriding this method MUST override isReverseOf as well if they change the behavior at all (for example, caching does not require overriding it).

    Definition Classes
    Ordering → PartialOrdering
  36. def reversed(): Comparator[Double]
    Definition Classes
    Comparator
  37. final def synchronized[T0](arg0: => T0): T0

    Executes the code in body with an exclusive lock on this.

    Executes the code in body with an exclusive lock on this.

    returns

    the result of body

    Definition Classes
    AnyRef
  38. def thenComparing[U <: Comparable[_ >: U <: AnyRef]](arg0: java.util.function.Function[_ >: Double <: AnyRef, _ <: U]): Comparator[Double]
    Definition Classes
    Comparator
  39. def thenComparing[U <: AnyRef](arg0: java.util.function.Function[_ >: Double <: AnyRef, _ <: U], arg1: Comparator[_ >: U <: AnyRef]): Comparator[Double]
    Definition Classes
    Comparator
  40. def thenComparing(arg0: Comparator[_ >: Double <: AnyRef]): Comparator[Double]
    Definition Classes
    Comparator
  41. def thenComparingDouble(arg0: ToDoubleFunction[_ >: Double <: AnyRef]): Comparator[Double]
    Definition Classes
    Comparator
  42. def thenComparingInt(arg0: ToIntFunction[_ >: Double <: AnyRef]): Comparator[Double]
    Definition Classes
    Comparator
  43. def thenComparingLong(arg0: ToLongFunction[_ >: Double <: AnyRef]): Comparator[Double]
    Definition Classes
    Comparator
  44. def toString(): String

    Creates a String representation of this object.

    Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.

    returns

    a String representation of the object.

    Definition Classes
    AnyRef → Any
  45. def tryCompare(x: Double, y: Double): Some[Int]

    Returns whether a comparison between x and y is defined, and if so the result of compare(x, y).

    Returns whether a comparison between x and y is defined, and if so the result of compare(x, y).

    Definition Classes
    Ordering → PartialOrdering
  46. final def wait(): Unit

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.

    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
    Note

    not specified by SLS as a member of AnyRef

  47. final def wait(arg0: Long, arg1: Int): Unit

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-

    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
    Note

    not specified by SLS as a member of AnyRef

  48. final def wait(arg0: Long): Unit

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.

    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException]) @native()
    Note

    not specified by SLS as a member of AnyRef

Deprecated Value Members

  1. def →[B](y: B): (IeeeOrdering, B)
    Implicit
    This member is added by an implicit conversion from IeeeOrdering toArrowAssoc[IeeeOrdering] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @deprecated
    Deprecated

    (Since version 2.13.0) Use -> instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.

Inherited from Ordering[Double]

Inherited from PartialOrdering[Double]

Inherited from Equiv[Double]

Inherited from java.io.Serializable

Inherited from Comparator[Double]

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion any2stringadd fromIeeeOrdering to any2stringadd[IeeeOrdering]

Inherited by implicit conversion StringFormat fromIeeeOrdering to StringFormat[IeeeOrdering]

Inherited by implicit conversion Ensuring fromIeeeOrdering to Ensuring[IeeeOrdering]

Inherited by implicit conversion ArrowAssoc fromIeeeOrdering to ArrowAssoc[IeeeOrdering]

Ungrouped