scala.reflect.api.Types

# SingletonType

#### abstract type SingletonType >: Null <: Universe.SingletonTypeApi with Universe.Type

The type of Scala singleton types, i.e., types that are inhabited by only one nun-null value. These include types of the forms

    C.this.type
    C.super.type
    x.type

as well as constant types.

Source
  Types.scala

Linear Supertypes
Universe.<refinement>, Universe.TypeApi, Universe.SingletonTypeApi, AnyRef, Any
Known Subclasses
ConstantType, SingleType, SuperType, ThisType
Ordering

1. Grouped
2. Alphabetic
3. By inheritance

Inherited

1. SingletonType
2. <refinement>
3. TypeApi
4. SingletonTypeApi
5. AnyRef
6. Any

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Visibility

1. Public
2. All

### Abstract Value Members

1. #### abstract def <:<(that: Universe.Type): Boolean

   Does this type conform to given type argument `that`?

   Does this type conform to given type argument `that`?

   Definition Classes
     TypeApi

2. #### abstract def =:=(that: Universe.Type): Boolean

   Is this type equivalent to given type argument `that`?

   Is this type equivalent to given type argument `that`?

   Definition Classes
     TypeApi

3. #### abstract def asSeenFrom(pre: Universe.Type, clazz: Universe.Symbol): Universe.Type

   This type as seen from prefix `pre` and class `clazz`.

   This type as seen from prefix `pre` and class `clazz`. This means: Replace all `ThisType`s of `clazz` or one of its subclasses by `pre` and instantiate all parameters by arguments of `pre`. Proceed analogously for `ThisType`s referring to outer classes.

   Example:

       scala> import scala.reflect.runtime.universe._
       import scala.reflect.runtime.universe._

       scala> class D[T] { def m: T = ??? }
       defined class D

       scala> class C extends D[Int]
       defined class C

       scala> val D = typeOf[D[_]].typeSymbol.asClass
       D: reflect.runtime.universe.ClassSymbol = class D

       scala> val C = typeOf[C].typeSymbol.asClass
       C: reflect.runtime.universe.ClassSymbol = class C

       scala> val T = D.typeParams(0).asType.toType
       T: reflect.runtime.universe.Type = T

       scala> T.asSeenFrom(ThisType(C), D)
       res0: reflect.runtime.universe.Type = scala.Int

   Definition Classes
     TypeApi

4. #### abstract def baseClasses: List[Universe.Symbol]

   The list of all base classes of this type (including its own typeSymbol) in linearization order, starting with the class itself and ending in class Any.

   The list of all base classes of this type (including its own typeSymbol) in linearization order, starting with the class itself and ending in class Any.

   Definition Classes
     TypeApi

5. #### abstract def baseType(clazz: Universe.Symbol): Universe.Type

   The least type instance of given class which is a super-type of this type.

   The least type instance of given class which is a super-type of this type. Example:

       class D[T]
       class C extends p.D[Int]
       ThisType(C).baseType(D) = p.D[Int]

   Definition Classes
     TypeApi

6. #### abstract def companion: Universe.Type

   Type signature of the companion of the underlying class symbol.

   Type signature of the companion of the underlying class symbol. NoType if the underlying symbol is not a class symbol, or if it doesn't have a companion.

   Definition Classes
     TypeApi

7. #### abstract def contains(sym: Universe.Symbol): Boolean

   Does this type contain a reference to given symbol?

   Does this type contain a reference to given symbol?

   Definition Classes
     TypeApi

8. #### abstract def dealias: Universe.Type

   Expands type aliases arising from type members.

   Expands type aliases arising from type members. Note that type aliases can hide beneath singleton types and singleton types can hide inside type aliases. Moreover, aliases might lurk in the upper bounds of abstract types. Therefore careful thought has to be applied to identify and carry out unwrapping logic specific to your use case.

   Definition Classes
     TypeApi

9. #### abstract def decl(name: Universe.Name): Universe.Symbol

   The defined or declared members with name `name` in this type; an OverloadedSymbol if several exist, NoSymbol if none exist.

   The defined or declared members with name `name` in this type; an OverloadedSymbol if several exist, NoSymbol if none exist. Alternatives of overloaded symbol appear in the order they are declared.

   Definition Classes
     TypeApi

10. #### abstract def decls: Universe.MemberScope

    A `Scope` containing directly declared members of this type.

    A `Scope` containing directly declared members of this type. Unlike `members` this method doesn't returns inherited members.

    Members in the returned scope might appear in arbitrary order. Use `declarations.sorted` to get an ordered list of members.

    Definition Classes
      TypeApi

11. #### abstract def erasure: Universe.Type

    The erased type corresponding to this type after all transformations from Scala to Java have been performed.

    The erased type corresponding to this type after all transformations from Scala to Java have been performed.

    Definition Classes
      TypeApi

12. #### abstract def etaExpand: Universe.Type

    Converts higher-kinded TypeRefs to PolyTypes.

    Converts higher-kinded TypeRefs to PolyTypes. Functions on types are also implemented as PolyTypes.

    Example: (in the below, <List> is the type constructor of List) TypeRef(pre, <List>, List()) is replaced by PolyType(X, TypeRef(pre, <List>, List(X)))

    Definition Classes
      TypeApi

13. #### abstract def exists(p: (Universe.Type) ⇒ Boolean): Boolean

    Is there part of this type which satisfies predicate `p`?

    Is there part of this type which satisfies predicate `p`?

    Definition Classes
      TypeApi

14. #### abstract def finalResultType: Universe.Type

    For a curried/nullary method or poly type its non-method result type, the type itself for all other types.

    For a curried/nullary method or poly type its non-method result type, the type itself for all other types.

        scala> class C {
             | def foo[T](x: T)(y: T) = ???
             | def bar: Int = ???
             | }
        defined class C

        scala> typeOf[C].member(TermName("foo")).asMethod
        res0: reflect.runtime.universe.MethodSymbol = method foo

        scala> res0.info // PolyType wrapping a MethodType
        res1: reflect.runtime.universe.Type = [T](x: T)(y: T)scala.Nothing

        scala> res1.resultType // MethodType wrapping a MethodType
        res2: reflect.runtime.universe.Type = (x: T)(y: T)scala.Nothing

        scala> res1.resultType.resultType // vanilla MethodType
        res3: reflect.runtime.universe.Type = (y: T)scala.Nothing

        scala> res1.resultType.resultType.resultType
        res4: reflect.runtime.universe.Type = scala.Nothing

        scala> res1.finalResultType
        res5: reflect.runtime.universe.Type = scala.Nothing

        scala> typeOf[C].member(TermName("bar")).asMethod
        res6: reflect.runtime.universe.MethodSymbol = method bar

        scala> res6.info
        res7: reflect.runtime.universe.Type = => scala.Int

        scala> res6.info.resultType
        res8: reflect.runtime.universe.Type = scala.Int

        scala> res6.info.finalResultType
        res9: reflect.runtime.universe.Type = scala.Int

    Definition Classes
      TypeApi
    See also

      resultType

15. #### abstract def find(p: (Universe.Type) ⇒ Boolean): Option[Universe.Type]

    Returns optionally first type (in a preorder traversal) which satisfies predicate `p`, or None if none exists.

    Returns optionally first type (in a preorder traversal) which satisfies predicate `p`, or None if none exists.

    Definition Classes
      TypeApi

16. #### abstract def foreach(f: (Universe.Type) ⇒ Unit): Unit

    Apply `f` to each part of this type, for side effects only

    Apply `f` to each part of this type, for side effects only

    Definition Classes
      TypeApi

17. #### abstract def map(f: (Universe.Type) ⇒ Universe.Type): Universe.Type

    Apply `f` to each part of this type, returning a new type.

    Apply `f` to each part of this type, returning a new type. children get mapped before their parents

    Definition Classes
      TypeApi

18. #### abstract def member(name: Universe.Name): Universe.Symbol

    The member with given name, either directly declared or inherited, an OverloadedSymbol if several exist, NoSymbol if none exist.

    The member with given name, either directly declared or inherited, an OverloadedSymbol if several exist, NoSymbol if none exist.

    Definition Classes
      TypeApi

19. #### abstract def members: Universe.MemberScope

    A `Scope` containing all members of this type (directly declared or inherited).

    A `Scope` containing all members of this type (directly declared or inherited). Unlike `declarations` this method also returns inherited members.

    Members in the returned scope might appear in arbitrary order. Use `declarations.sorted` to get an ordered list of members.

    Definition Classes
      TypeApi

20. #### abstract def orElse(alt: ⇒ Universe.Type): Universe.Type

    Provides an alternate if type is NoType.

    Provides an alternate if type is NoType.

    Definition Classes
      TypeApi

21. #### abstract def paramLists: List[List[Universe.Symbol]]

    For a method or poly type, a list of its value parameter sections, the empty list of lists for all other types.

    For a method or poly type, a list of its value parameter sections, the empty list of lists for all other types.

    Definition Classes
      TypeApi

22. #### abstract def resultType: Universe.Type

    For a (nullary) method or poly type, its direct result type (can be a MethodType if the method has multiple argument lists), the type itself for all other types.

    For a (nullary) method or poly type, its direct result type (can be a MethodType if the method has multiple argument lists), the type itself for all other types.

        scala> class C { def foo[T](x: T)(y: T) = ??? }
        defined class C

        scala> typeOf[C].member(TermName("foo")).asMethod
        res0: reflect.runtime.universe.MethodSymbol = method foo

        scala> res0.info // PolyType wrapping a MethodType
        res1: reflect.runtime.universe.Type = [T](x: T)(y: T)scala.Nothing

        scala> res1.resultType // MethodType wrapping a MethodType
        res2: reflect.runtime.universe.Type = (x: T)(y: T)scala.Nothing

        scala> res1.resultType.resultType // vanilla MethodType
        res3: reflect.runtime.universe.Type = (y: T)scala.Nothing

        scala> res1.resultType.resultType.resultType
        res4: reflect.runtime.universe.Type = scala.Nothing

        scala> res1.finalResultType
        res5: reflect.runtime.universe.Type = scala.Nothing

    Definition Classes
      TypeApi
    See also

      finalResultType

23. #### abstract def substituteSymbols(from: List[Universe.Symbol], to: List[Universe.Symbol]): Universe.Type

    Substitute symbols in `to` for corresponding occurrences of references to symbols `from` in this type.

    Substitute symbols in `to` for corresponding occurrences of references to symbols `from` in this type.

    Definition Classes
      TypeApi

24. #### abstract def substituteTypes(from: List[Universe.Symbol], to: List[Universe.Type]): Universe.Type

    Substitute types in `to` for corresponding occurrences of references to symbols `from` in this type.

    Substitute types in `to` for corresponding occurrences of references to symbols `from` in this type.

    Definition Classes
      TypeApi

25. #### abstract def takesTypeArgs: Boolean

    Is this type a type constructor that is missing its type arguments?

    Is this type a type constructor that is missing its type arguments?

    Definition Classes
      TypeApi

26. #### abstract def termSymbol: Universe.Symbol

    The term symbol associated with the type, or `NoSymbol` for types that do not refer to a term symbol.

    The term symbol associated with the type, or `NoSymbol` for types that do not refer to a term symbol.

    Definition Classes
      TypeApi

27. #### abstract def typeArgs: List[Universe.Type]

    List of type arguments ingrained in this type reference.

    List of type arguments ingrained in this type reference. Depending on your use case you might or might not want to call `dealias` first.

        scala> type T = List[Int]
        defined type alias T

        scala> typeOf[T].typeArgs
        res0: List[reflect.runtime.universe.Type] = List()

        scala> typeOf[T].dealias.typeArgs
        res1: List[reflect.runtime.universe.Type] = List(scala.Int)

    Definition Classes
      TypeApi

28. #### abstract def typeConstructor: Universe.Type

    Returns the corresponding type constructor (e.g.

    Returns the corresponding type constructor (e.g. List for List[T] or List[String])

    Definition Classes
      TypeApi

29. #### abstract def typeParams: List[Universe.Symbol]

    For a poly type, its type parameters, the empty list for all other types.

    For a poly type, its type parameters, the empty list for all other types.

    Definition Classes
      TypeApi

30. #### abstract def typeSymbol: Universe.Symbol

    The type symbol associated with the type, or `NoSymbol` for types that do not refer to a type symbol.

    The type symbol associated with the type, or `NoSymbol` for types that do not refer to a type symbol.

    Definition Classes
      TypeApi

31. #### abstract def weak_<:<(that: Universe.Type): Boolean

    Does this type weakly conform to given type argument `that`, i.e., either conforms in terms of `<:<` or both are primitive number types that conform according to Section "Weak Conformance" in the spec.

    Does this type weakly conform to given type argument `that`, i.e., either conforms in terms of `<:<` or both are primitive number types that conform according to Section "Weak Conformance" in the spec. For example, Int weak_<:< Long.

    Definition Classes
      TypeApi

32. #### abstract def widen: Universe.Type

    If this is a singleton type, widen it to its nearest underlying non-singleton base type by applying one or more `underlying` dereferences.

    If this is a singleton type, widen it to its nearest underlying non-singleton base type by applying one or more `underlying` dereferences. If this is not a singleton type, returns this type itself.

    Example:

    class Outer { class C ; val x: C } val o: Outer <o.x.type>.widen = o.C

    Note that type aliases can hide beneath singleton types and singleton types can hide inside type aliases. Moreover, aliases might lurk in the upper bounds of abstract types. Therefore careful thought has to be applied to identify and carry out unwrapping logic specific to your use case.

    Definition Classes
      TypeApi

33. #### abstract def declaration(name: Universe.Name): Universe.Symbol

    Definition Classes
      TypeApi
    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) Use `decl` instead

    See also

      decl

34. #### abstract def declarations: Universe.MemberScope

    Definition Classes
      TypeApi
    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) Use `decls` instead

    See also

      decls

35. #### abstract def normalize: Universe.Type

    Reduce to beta eta-long normal form.

    Reduce to beta eta-long normal form. Expands type aliases and converts higher-kinded TypeRefs to PolyTypes. Functions on types are also implemented as PolyTypes.

    Example: (in the below, <List> is the type constructor of List) TypeRef(pre, <List>, List()) is replaced by PolyType(X, TypeRef(pre, <List>, List(X)))

    Definition Classes
      TypeApi
    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) Use `dealias` or `etaExpand` instead

36. #### abstract def paramss: List[List[Universe.Symbol]]

    Definition Classes
      TypeApi
    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) Use `paramLists` instead

    See also

      paramLists

### Concrete Value Members

1. #### final def !=(arg0: Any): Boolean

   Definition Classes
     AnyRef → Any

2. #### final def ##(): Int

   Definition Classes
     AnyRef → Any

3. #### final def ==(arg0: Any): Boolean

   Definition Classes
     AnyRef → Any

4. #### final def asInstanceOf[T0]: T0

   Definition Classes
     Any

5. #### def clone(): AnyRef

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

6. #### final def eq(arg0: AnyRef): Boolean

   Definition Classes
     AnyRef

7. #### def equals(arg0: Any): Boolean

   Definition Classes
     AnyRef → Any

8. #### def finalize(): Unit

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

9. #### final def getClass(): Class[_]

   Definition Classes
     AnyRef → Any

10. #### def hashCode(): Int

    Definition Classes
      AnyRef → Any

11. #### final def isInstanceOf[T0]: Boolean

    Definition Classes
      Any

12. #### final def ne(arg0: AnyRef): Boolean

    Definition Classes
      AnyRef

13. #### final def notify(): Unit

    Definition Classes
      AnyRef

14. #### final def notifyAll(): Unit

    Definition Classes
      AnyRef

15. #### final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
      AnyRef

16. #### def toString(): String

    Definition Classes
      AnyRef → Any

17. #### final def wait(): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

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

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

19. #### final def wait(arg0: Long): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

### Inherited from Universe.<refinement>

### Inherited from Universe.TypeApi

### Inherited from Universe.SingletonTypeApi

### Inherited from AnyRef

### Inherited from Any

### Helpers

### Ungrouped