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

Scala 2.10.0 changed the implementation oflt,equiv,min, etc., to be IEEE 754 compliant, while keeping thecompare method NOT compliant, creating an internally inconsistent instance. IEEE 754 specifies that0.0 == -0.0. In addition, it requires all comparisons withDouble.NaN returnfalse thus0.0 < Double.NaN,0.0 > Double.NaN, andDouble.NaN == Double.NaN all yieldfalse, analogousNone inflatMap.

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, andOrdering.Double.TotalOrdering, which brings back thejava.lang.Double.compare semantics for all operations. The default extendsTotalOrdering.

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         // -Infinityimplicitly[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}

Attributes

Source: Ordering.scala
Supertypes: classObject
traitMatchable
classAny
Self type: Double.type

traitExtraImplicits

Attributes

Source: Ordering.scala
Supertypes: classObject
traitMatchable
classAny
Known subtypes: objectImplicits

objectFloat

Orderings forFloats.

The default extendsOrdering.Float.TotalOrdering.

Ordering.Float.TotalOrdering uses thejava.lang.Float.compare semantics for all operations. Scala also provides theOrdering.Float.IeeeOrdering semantics. Which uses the IEEE 754 semantics for float ordering.

Historically:IeeeOrdering was used in Scala from 2.10.x through 2.12.x. This changed in 2.13.0 toTotalOrdering.

Prior to Scala 2.10.0, theOrdering instance used semantics consistent withjava.lang.Float.compare.

Scala 2.10.0 changed the implementation oflt,equiv,min, etc., to be IEEE 754 compliant, while keeping thecompare method NOT compliant, creating an internally inconsistent instance. IEEE 754 specifies that0.0F == -0.0F. In addition, it requires all comparisons withFloat.NaN returnfalse thus0.0F < Float.NaN,0.0F > Float.NaN, andFloat.NaN == Float.NaN all yieldfalse, analogousNone inflatMap.

List(0.0F, 1.0F, 0.0F / 0.0F, -1.0F / 0.0F).sorted      // List(-Infinity, 0.0, 1.0, NaN)List(0.0F, 1.0F, 0.0F / 0.0F, -1.0F / 0.0F).min         // -Infinityimplicitly[Ordering[Float]].lt(0.0F, 0.0F / 0.0F)       // true{  import Ordering.Float.IeeeOrdering  List(0.0F, 1.0F, 0.0F / 0.0F, -1.0F / 0.0F).sorted    // List(-Infinity, 0.0, 1.0, NaN)  List(0.0F, 1.0F, 0.0F / 0.0F, -1.0F / 0.0F).min       // NaN  implicitly[Ordering[Float]].lt(0.0F, 0.0F / 0.0F)     // false}

Attributes

Source: Ordering.scala
Supertypes: classObject
traitMatchable
classAny
Self type: Float.type

objectImplicits extendsExtraImplicits

An object containing implicits which are not in the default scope.

Attributes

Source: Ordering.scala
Supertypes: traitExtraImplicits
classObject
traitMatchable
classAny
Self type: Implicits.type

objectInt extendsIntOrdering,CachedReverse[Int]

Attributes

Source: Ordering.scala
Supertypes: traitCachedReverse[Int]
traitIntOrdering
traitOrdering[Int]
traitPartialOrdering[Int]
traitEquiv[Int]
traitSerializable
traitComparator[Int]
classObject
traitMatchable
classAny
Show all
Self type: Int.type

traitIntOrdering extendsOrdering[Int]

Attributes

Source: Ordering.scala
Supertypes: traitOrdering[Int]
traitPartialOrdering[Int]
traitEquiv[Int]
traitSerializable
traitComparator[Int]
classObject
traitMatchable
classAny
Show all
Known subtypes: objectIntIsIntegral
objectInt

objectLong extendsLongOrdering

Attributes

Source: Ordering.scala
Supertypes: traitLongOrdering
traitOrdering[Long]
traitPartialOrdering[Long]
traitEquiv[Long]
traitSerializable
traitComparator[Long]
classObject
traitMatchable
classAny
Show all
Self type: Long.type

traitLongOrdering extendsOrdering[Long]

Attributes

Source: Ordering.scala
Supertypes: traitOrdering[Long]
traitPartialOrdering[Long]
traitEquiv[Long]
traitSerializable
traitComparator[Long]
classObject
traitMatchable
classAny
Show all
Known subtypes: objectLongIsIntegral
objectLong

traitOptionOrdering[T] extendsOrdering[Option[T]]

Attributes

Source: Ordering.scala
Supertypes: traitOrdering[Option[T]]
traitPartialOrdering[Option[T]]
traitEquiv[Option[T]]
traitSerializable
traitComparator[Option[T]]
classObject
traitMatchable
classAny
Show all

objectShort extendsShortOrdering

Attributes

Source: Ordering.scala
Supertypes: traitShortOrdering
traitOrdering[Short]
traitPartialOrdering[Short]
traitEquiv[Short]
traitSerializable
traitComparator[Short]
classObject
traitMatchable
classAny
Show all
Self type: Short.type

traitShortOrdering extendsOrdering[Short]

Attributes

Source: Ordering.scala
Supertypes: traitOrdering[Short]
traitPartialOrdering[Short]
traitEquiv[Short]
traitSerializable
traitComparator[Short]
classObject
traitMatchable
classAny
Show all
Known subtypes: objectShortIsIntegral
objectShort

objectString extendsStringOrdering

Attributes

Source: Ordering.scala
Supertypes: traitStringOrdering
traitOrdering[String]
traitPartialOrdering[String]
traitEquiv[String]
traitSerializable
traitComparator[String]
classObject
traitMatchable
classAny
Show all
Self type: String.type

traitStringOrdering extendsOrdering[String]

Attributes

Source: Ordering.scala
Supertypes: traitOrdering[String]
traitPartialOrdering[String]
traitEquiv[String]
traitSerializable
traitComparator[String]
classObject
traitMatchable
classAny
Show all
Known subtypes: objectString

objectSymbol extendsSymbolOrdering

Attributes

Source: Ordering.scala
Supertypes: traitSymbolOrdering
traitOrdering[Symbol]
traitPartialOrdering[Symbol]
traitEquiv[Symbol]
traitSerializable
traitComparator[Symbol]
classObject
traitMatchable
classAny
Show all
Self type: Symbol.type

traitSymbolOrdering extendsOrdering[Symbol]

Attributes

Source: Ordering.scala
Supertypes: traitOrdering[Symbol]
traitPartialOrdering[Symbol]
traitEquiv[Symbol]
traitSerializable
traitComparator[Symbol]
classObject
traitMatchable
classAny
Show all
Known subtypes: objectSymbol

objectUnit extendsUnitOrdering

Attributes

Source: Ordering.scala
Supertypes: traitUnitOrdering
traitOrdering[Unit]
traitPartialOrdering[Unit]
traitEquiv[Unit]
traitSerializable
traitComparator[Unit]
classObject
traitMatchable
classAny
Show all
Self type: Unit.type

traitUnitOrdering extendsOrdering[Unit]

Attributes

Source: Ordering.scala
Supertypes: traitOrdering[Unit]
traitPartialOrdering[Unit]
traitEquiv[Unit]
traitSerializable
traitComparator[Unit]
classObject
traitMatchable
classAny
Show all
Known subtypes: objectUnit

Inherited types

typeAsComparable[A] =A=>Comparable[_ >:A]

Attributes

Inherited from:: LowPriorityOrderingImplicits
Source: Ordering.scala

Value members

Concrete methods

defapply[T](implicitord:Ordering[T]):Ordering[T]

Attributes

Source: Ordering.scala

defby[T,S](f:T=>S)(implicitord:Ordering[S]):Ordering[T]

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

def compare(x:T, y:T) = Ordering[S].compare(f(x), f(y))

This function is an analogue to Ordering.on where the Ordering[S] parameter is passed implicitly.

Attributes

Source: Ordering.scala

deffromLessThan[T](cmp: (T,T)=>Boolean):Ordering[T]

Construct an Ordering[T] given a functionlt.

Attributes

Source: Ordering.scala

Implicits

implicitdefOption[T](implicitord:Ordering[T]):Ordering[Option[T]]

Attributes

Source: Ordering.scala

implicitdefTuple2[T1,T2](implicitord1:Ordering[T1],ord2:Ordering[T2]):Ordering[(T1,T2)]

Attributes

Source: Ordering.scala

implicitdefTuple3[T1,T2,T3](implicitord1:Ordering[T1],ord2:Ordering[T2],ord3:Ordering[T3]):Ordering[(T1,T2,T3)]

Attributes

Source: Ordering.scala

implicitdefTuple4[T1,T2,T3,T4](implicitord1:Ordering[T1],ord2:Ordering[T2],ord3:Ordering[T3],ord4:Ordering[T4]):Ordering[(T1,T2,T3,T4)]

Attributes

Source: Ordering.scala

implicitdefTuple5[T1,T2,T3,T4,T5](implicitord1:Ordering[T1],ord2:Ordering[T2],ord3:Ordering[T3],ord4:Ordering[T4],ord5:Ordering[T5]):Ordering[(T1,T2,T3,T4,T5)]

Attributes

Source: Ordering.scala

implicitdefTuple6[T1,T2,T3,T4,T5,T6](implicitord1:Ordering[T1],ord2:Ordering[T2],ord3:Ordering[T3],ord4:Ordering[T4],ord5:Ordering[T5],ord6:Ordering[T6]):Ordering[(T1,T2,T3,T4,T5,T6)]

Attributes

Source: Ordering.scala

implicitdefTuple7[T1,T2,T3,T4,T5,T6,T7](implicitord1:Ordering[T1],ord2:Ordering[T2],ord3:Ordering[T3],ord4:Ordering[T4],ord5:Ordering[T5],ord6:Ordering[T6],ord7:Ordering[T7]):Ordering[(T1,T2,T3,T4,T5,T6,T7)]

Attributes

Source: Ordering.scala

implicitdefTuple8[T1,T2,T3,T4,T5,T6,T7,T8](implicitord1:Ordering[T1],ord2:Ordering[T2],ord3:Ordering[T3],ord4:Ordering[T4],ord5:Ordering[T5],ord6:Ordering[T6],ord7:Ordering[T7],ord8:Ordering[T8]):Ordering[(T1,T2,T3,T4,T5,T6,T7,T8)]

Attributes

Source: Ordering.scala

implicitdefTuple9[T1,T2,T3,T4,T5,T6,T7,T8,T9](implicitord1:Ordering[T1],ord2:Ordering[T2],ord3:Ordering[T3],ord4:Ordering[T4],ord5:Ordering[T5],ord6:Ordering[T6],ord7:Ordering[T7],ord8:Ordering[T8],ord9:Ordering[T9]):Ordering[(T1,T2,T3,T4,T5,T6,T7,T8,T9)]

Attributes

Source: Ordering.scala

Deprecated implicits

implicitdefIterable[T](implicitord:Ordering[T]):Ordering[Iterable[T]]

Attributes

Deprecated: [Since version 2.13.0]Iterables are not guaranteed to have a consistent order; if using a type with a ".+("consistent order (e.g. Seq), use its Ordering (found in the Ordering.Implicits object)")
Iterables are not guaranteed to have a consistent order, so theOrdering returned by this method may not be stable or meaningful. If you are using a type with a consistent order (such asSeq), use itsOrdering (found in theImplicits object) instead.
Source: Ordering.scala

Inherited implicits

implicitdefcomparatorToOrdering[A](implicitcmp:Comparator[A]):Ordering[A]

Attributes

Inherited from:: LowPriorityOrderingImplicits
Source: Ordering.scala

implicitdefordered[A](implicitasComparable:A=>Comparable[_ >:A]):Ordering[A]

This would conflict with all the nice implicit Orderings available, but thanks to the magic of prioritized implicits via subclassing we can makeOrdered[A] => Ordering[A] only turn up if nothing else works.

Attributes

Inherited from:: LowPriorityOrderingImplicits
Source: Ordering.scala

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