Scala Reflection Library2.12.21 < Back
 

# Packages

-  package root
  Definition Classes
    root
-  package scala
  Definition Classes
    root
-  package reflect
  Definition Classes
    scala
-  package api

  EXPERIMENTAL

  EXPERIMENTAL

  The Scala Reflection API (located in scala-reflect.jar).

  In Scala 2.10.0, the Scala Reflection API and its implementation have an "experimental" status. This means that the API and the docs are not complete and can be changed in binary- and source-incompatible manner in 2.10.1. This also means that the implementation has some known issues.

  The following types are the backbone of the Scala Reflection API, and serve as a good starting point for information about Scala Reflection:

  - scala.reflect.api.Symbols
  - scala.reflect.api.Types
  - scala.reflect.api.Mirrors
  - scala.reflect.api.Universe

  For more information about Scala Reflection, see the Reflection Guide

  Definition Classes
    reflect
-  trait Types extends AnyRef

  EXPERIMENTAL

  EXPERIMENTAL

  A trait that defines types and operations on them.

  Type instances represent information about the type of a corresponding symbol. This includes its members (methods, fields, type parameters, nested classes, traits, etc.) either declared directly or inherited, its base types, its erasure and so on. Types also provide operations to test for type conformance or equivalence or for widening.

  To instantiate a type, most of the time, the scala.reflect.api.TypeTags#typeOf method can be used. It takes a type argument and produces a `Type` instance which represents that argument. For example:

      scala> typeOf[List[Int]]
      res0: reflect.runtime.universe.Type = scala.List[Int]

  In this example, a scala.reflect.api.Types#TypeRef is returned, which corresponds to the type constructor `List` applied to the type argument `Int`.

  Note: Method `typeOf` does not work for types with type parameters, such as `typeOf[List[A]]` where `A` is a type parameter. In this case, use scala.reflect.api.TypeTags#weakTypeOf instead.

  For other ways to instantiate types, see the corresponding section of the Reflection Guide.

  ##### Common Operations on Types

  Types are typically used for type conformance tests or are queried for declarations of members or inner types.

  - Subtyping Relationships can be tested using `<:<` and `weak_<:<`.
  - Type Equality can be checked with `=:=`. It's important to note that `==` should not be used to compare types for equality-- `==` can't check for type equality in the presence of type aliases, while `=:=` can.

  Types can be queried for members and declarations by using the `members` and `declarations` methods (along with their singular counterparts `member` and `declaration`), which provide the list of definitions associated with that type. For example, to look up the `map` method of `List`, one can do:

      scala> typeOf[List[_]].member("map": TermName)
      res1: reflect.runtime.universe.Symbol = method map

  For more information about `Type`s, see the Reflection Guide: Symbols, Trees, and Types

  Definition Classes
    api
- AnnotatedType
- AnnotatedTypeApi
- AnnotatedTypeExtractor
- BoundedWildcardType
- BoundedWildcardTypeApi
- BoundedWildcardTypeExtractor
- ClassInfoType
- ClassInfoTypeApi
- ClassInfoTypeExtractor
- CompoundType
- CompoundTypeApi
- ConstantType
- ConstantTypeApi
- ConstantTypeExtractor
- ExistentialType
- ExistentialTypeApi
- ExistentialTypeExtractor
- MethodType
- MethodTypeApi
- MethodTypeExtractor
- NullaryMethodType
- NullaryMethodTypeApi
- NullaryMethodTypeExtractor
- PolyType
- PolyTypeApi
- PolyTypeExtractor
- RefinedType
- RefinedTypeApi
- RefinedTypeExtractor
- SingleType
- SingleTypeApi
- SingleTypeExtractor
- SingletonType
- SingletonTypeApi
- SuperType
- SuperTypeApi
- SuperTypeExtractor
- ThisType
- ThisTypeApi
- ThisTypeExtractor
- Type
- TypeApi
- TypeBounds
- TypeBoundsApi
- TypeBoundsExtractor
- TypeRef
- TypeRefApi
- TypeRefExtractor

a

scala.reflect.api.Types

# TypeRef 

###
Companion class TypeRefExtractor

#### abstract type TypeRef >: Null <: Universe.TypeRefApi with Universe.Type

The `TypeRef` type describes types of any of the forms on the left, with their TypeRef representations to the right.

    T # C[T_1, ..., T_n]      TypeRef(T, C, List(T_1, ..., T_n))
    p.C[T_1, ..., T_n]        TypeRef(p.type, C, List(T_1, ..., T_n))
    C[T_1, ..., T_n]          TypeRef(NoPrefix, C, List(T_1, ..., T_n))
    T # C                     TypeRef(T, C, Nil)
    p.C                       TypeRef(p.type, C, Nil)
    C                         TypeRef(NoPrefix, C, Nil)

Source
  Types.scala

Linear Supertypes
Universe.<refinement>, Universe.TypeRefApi, Universe.TypeApi, AnyRef, Any
 
Ordering

1. Grouped
2. Alphabetic
3. By Inheritance

Inherited

1. TypeRef
2. <refinement>
3. TypeRefApi
4. TypeApi
5. AnyRef
6. Any

1. Hide All
2. Show All

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 args: List[Universe.Type]

   The arguments of the type reference.

   The arguments of the type reference. Is equal to `Nil` if the arguments are not provided.

   Definition Classes
     TypeRefApi
4.  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
5.  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
6.  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
7.  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
8.  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
9.  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
10.  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
11.  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
12.  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
13.  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
14.  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
15.  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

16.  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
17.  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
18.  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
19.  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
20.  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
21.  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
22.  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
23.  abstract def pre: Universe.Type

    The prefix of the type reference.

    The prefix of the type reference. Is equal to `NoPrefix` if the prefix is not applicable.

    Definition Classes
      TypeRefApi
24.  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

25.  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
26.  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
27.  abstract def sym: Universe.Symbol

    The underlying symbol of the type reference.

    The underlying symbol of the type reference.

    Definition Classes
      TypeRefApi
28.  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
29.  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
30.  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
31.  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
32.  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
33.  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
34.  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
35.  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
36.  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

37.  abstract def declarations: Universe.MemberScope

    Definition Classes
      TypeApi
    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) use `decls` instead

    See also

      decls

38.  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

39.  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[lang]
   Definition Classes
     AnyRef
   Annotations
     @throws( ... ) @native()
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[lang]
   Definition Classes
     AnyRef
   Annotations
     @throws( classOf[java.lang.Throwable] )
9.  final def getClass(): Class[_]
   Definition Classes
     AnyRef → Any
   Annotations
     @native()
10.  def hashCode(): Int
    Definition Classes
      AnyRef → Any
    Annotations
      @native()
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
    Annotations
      @native()
14.  final def notifyAll(): Unit
    Definition Classes
      AnyRef
    Annotations
      @native()
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( ... ) @native()

### Inherited from Universe.<refinement>

### Inherited from Universe.TypeRefApi

### Inherited from Universe.TypeApi

### Inherited from AnyRef

### Inherited from Any

### Helpers

### Ungrouped