scala.reflect.api

Types

trait Types extends ImplicitTags

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.

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 Types, see the Reflection Guide: Symbols, Trees, and Types

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Universe
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Types.scala
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Type Members

  1. abstract type AnnotatedType >: Null <: Universe.Type with Universe.AnnotatedTypeApi

    The AnnotatedType type signature is used for annotated types of the for <type> @<annotation>.

  2. trait AnnotatedTypeApi extends Universe.TypeApi

    The API that all annotated types support.

  3. abstract class AnnotatedTypeExtractor extends AnyRef

    An extractor class to create and pattern match with syntax AnnotatedType(annotations, underlying, selfsym).

  4. abstract type BoundedWildcardType >: Null <: Universe.Type with Universe.BoundedWildcardTypeApi

    BoundedWildcardTypes, used only during type inference, are created in two places:

  5. trait BoundedWildcardTypeApi extends Universe.TypeApi

    The API that all this types support.

  6. abstract class BoundedWildcardTypeExtractor extends AnyRef

    An extractor class to create and pattern match with syntax BoundedWildcardTypeExtractor(bounds) with bounds denoting the type bounds.

  7. abstract type ClassInfoType >: Null <: Universe.CompoundType with Universe.ClassInfoTypeApi

    The ClassInfo type signature is used to define parents and declarations of classes, traits, and objects.

  8. trait ClassInfoTypeApi extends Universe.TypeApi

    The API that all class info types support.

  9. abstract class ClassInfoTypeExtractor extends AnyRef

    An extractor class to create and pattern match with syntax ClassInfo(parents, decls, clazz) Here, parents is the list of parent types of the class, decls is the scope containing all declarations in the class, and clazz is the symbol of the class itself.

  10. abstract type CompoundType >: Null <: Universe.Type

    A subtype of Type representing refined types as well as ClassInfo signatures.

  11. abstract type ConstantType >: Null <: Universe.SingletonType with Universe.ConstantTypeApi

    The ConstantType type is not directly written in user programs, but arises as the type of a constant.

  12. trait ConstantTypeApi extends Universe.TypeApi

    The API that all constant types support.

  13. abstract class ConstantTypeExtractor extends AnyRef

    An extractor class to create and pattern match with syntax ConstantType(constant) Here, constant is the constant value represented by the type.

  14. abstract type ExistentialType >: Null <: Universe.Type with Universe.ExistentialTypeApi

    The ExistentialType type signature is used for existential types and wildcard types.

  15. trait ExistentialTypeApi extends Universe.TypeApi

    The API that all existential types support.

  16. abstract class ExistentialTypeExtractor extends AnyRef

    An extractor class to create and pattern match with syntax ExistentialType(quantified, underlying).

  17. abstract type MethodType >: Null <: Universe.Type with Universe.MethodTypeApi

    The MethodType type signature is used to indicate parameters and result type of a method

  18. trait MethodTypeApi extends Universe.TypeApi

    The API that all method types support.

  19. abstract class MethodTypeExtractor extends AnyRef

    An extractor class to create and pattern match with syntax MethodType(params, respte) Here, params is a potentially empty list of parameter symbols of the method, and restpe is the result type of the method.

  20. abstract type NullaryMethodType >: Null <: Universe.Type with Universe.NullaryMethodTypeApi

    The NullaryMethodType type signature is used for parameterless methods with declarations of the form def foo: T

  21. trait NullaryMethodTypeApi extends Universe.TypeApi

    The API that all nullary method types support.

  22. abstract class NullaryMethodTypeExtractor extends AnyRef

    An extractor class to create and pattern match with syntax NullaryMethodType(resultType).

  23. abstract type PolyType >: Null <: Universe.Type with Universe.PolyTypeApi

    The PolyType type signature is used for polymorphic methods that have at least one type parameter.

  24. trait PolyTypeApi extends Universe.TypeApi

    The API that all polymorphic types support.

  25. abstract class PolyTypeExtractor extends AnyRef

    An extractor class to create and pattern match with syntax PolyType(typeParams, resultType).

  26. abstract type RefinedType >: Null <: Universe.CompoundType with Universe.RefinedTypeApi

    The RefinedType type defines types of any of the forms on the left, with their RefinedType representations to the right.

  27. trait RefinedTypeApi extends Universe.TypeApi

    The API that all refined types support.

  28. abstract class RefinedTypeExtractor extends AnyRef

    An extractor class to create and pattern match with syntax RefinedType(parents, decls) Here, parents is the list of parent types of the class, and decls is the scope containing all declarations in the class.

  29. abstract type SingleType >: Null <: Universe.SingletonType with Universe.SingleTypeApi

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

  30. trait SingleTypeApi extends Universe.TypeApi

    The API that all single types support.

  31. abstract class SingleTypeExtractor extends AnyRef

    An extractor class to create and pattern match with syntax SingleType(pre, sym) Here, pre is the prefix of the single-type, and sym is the stable value symbol referred to by the single-type.

  32. abstract type SingletonType >: Null <: Universe.Type

    The type of Scala singleton types, i.

  33. abstract type SuperType >: Null <: Universe.SingletonType with Universe.SuperTypeApi

    The SuperType type is not directly written, but arises when C.super is used as a prefix in a TypeRef or SingleType.

  34. trait SuperTypeApi extends Universe.TypeApi

    The API that all super types support.

  35. abstract class SuperTypeExtractor extends AnyRef

    An extractor class to create and pattern match with syntax SingleType(thistpe, supertpe)

  36. abstract type ThisType >: Null <: Universe.SingletonType with Universe.ThisTypeApi

    A singleton type that describes types of the form on the left with the corresponding ThisType representation to the right:

  37. trait ThisTypeApi extends Universe.TypeApi

    The API that all this types support.

  38. abstract class ThisTypeExtractor extends AnyRef

    An extractor class to create and pattern match with syntax ThisType(sym) where sym is the class prefix of the this type.

  39. abstract type Type >: Null <: Universe.TypeApi

    The type of Scala types, and also Scala type signatures.

  40. abstract class TypeApi extends AnyRef

    The API of types.

  41. abstract type TypeBounds >: Null <: Universe.Type with Universe.TypeBoundsApi

    The TypeBounds type signature is used to indicate lower and upper type bounds of type parameters and abstract types.

  42. trait TypeBoundsApi extends Universe.TypeApi

    The API that all type bounds support.

  43. abstract class TypeBoundsExtractor extends AnyRef

    An extractor class to create and pattern match with syntax TypeBound(lower, upper) Here, lower is the lower bound of the TypeBounds pair, and upper is the upper bound.

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

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

  45. trait TypeRefApi extends Universe.TypeApi

    The API that all type refs support.

  46. abstract class TypeRefExtractor extends AnyRef

    An extractor class to create and pattern match with syntax TypeRef(pre, sym, args) Here, pre is the prefix of the type reference, sym is the symbol referred to by the type reference, and args is a possible empty list of type argumenrts.

Abstract Value Members

  1. abstract val AnnotatedType: Universe.AnnotatedTypeExtractor

    The constructor/extractor for AnnotatedType instances.

  2. implicit abstract val AnnotatedTypeTag: ClassTag[Universe.AnnotatedType]

    A tag that preserves the identity of the AnnotatedType abstract type from erasure.

    A tag that preserves the identity of the AnnotatedType abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  3. abstract val BoundedWildcardType: Universe.BoundedWildcardTypeExtractor

    The constructor/extractor for BoundedWildcardType instances.

  4. implicit abstract val BoundedWildcardTypeTag: ClassTag[Universe.BoundedWildcardType]

    A tag that preserves the identity of the BoundedWildcardType abstract type from erasure.

    A tag that preserves the identity of the BoundedWildcardType abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  5. abstract val ClassInfoType: Universe.ClassInfoTypeExtractor

    The constructor/extractor for ClassInfoType instances.

  6. implicit abstract val ClassInfoTypeTag: ClassTag[Universe.ClassInfoType]

    A tag that preserves the identity of the ClassInfoType abstract type from erasure.

    A tag that preserves the identity of the ClassInfoType abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  7. implicit abstract val CompoundTypeTag: ClassTag[Universe.CompoundType]

    A tag that preserves the identity of the CompoundType abstract type from erasure.

    A tag that preserves the identity of the CompoundType abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  8. abstract val ConstantType: Universe.ConstantTypeExtractor

    The constructor/extractor for ConstantType instances.

  9. implicit abstract val ConstantTypeTag: ClassTag[Universe.ConstantType]

    A tag that preserves the identity of the ConstantType abstract type from erasure.

    A tag that preserves the identity of the ConstantType abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  10. abstract val ExistentialType: Universe.ExistentialTypeExtractor

    The constructor/extractor for ExistentialType instances.

  11. implicit abstract val ExistentialTypeTag: ClassTag[Universe.ExistentialType]

    A tag that preserves the identity of the ExistentialType abstract type from erasure.

    A tag that preserves the identity of the ExistentialType abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  12. abstract val MethodType: Universe.MethodTypeExtractor

    The constructor/extractor for MethodType instances.

  13. implicit abstract val MethodTypeTag: ClassTag[Universe.MethodType]

    A tag that preserves the identity of the MethodType abstract type from erasure.

    A tag that preserves the identity of the MethodType abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  14. abstract val NoPrefix: Universe.Type

    This constant is used as a special value denoting the empty prefix in a path dependent type.

    This constant is used as a special value denoting the empty prefix in a path dependent type. For instance x.type is represented as SingleType(NoPrefix, <x>), where <x> stands for the symbol for x.

  15. abstract val NoType: Universe.Type

    This constant is used as a special value that indicates that no meaningful type exists.

  16. abstract val NullaryMethodType: Universe.NullaryMethodTypeExtractor

    The constructor/extractor for NullaryMethodType instances.

  17. implicit abstract val NullaryMethodTypeTag: ClassTag[Universe.NullaryMethodType]

    A tag that preserves the identity of the NullaryMethodType abstract type from erasure.

    A tag that preserves the identity of the NullaryMethodType abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  18. abstract val PolyType: Universe.PolyTypeExtractor

    The constructor/extractor for PolyType instances.

  19. implicit abstract val PolyTypeTag: ClassTag[Universe.PolyType]

    A tag that preserves the identity of the PolyType abstract type from erasure.

    A tag that preserves the identity of the PolyType abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  20. abstract val RefinedType: Universe.RefinedTypeExtractor

    The constructor/extractor for RefinedType instances.

  21. implicit abstract val RefinedTypeTag: ClassTag[Universe.RefinedType]

    A tag that preserves the identity of the RefinedType abstract type from erasure.

    A tag that preserves the identity of the RefinedType abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  22. abstract val SingleType: Universe.SingleTypeExtractor

    The constructor/extractor for SingleType instances.

  23. implicit abstract val SingleTypeTag: ClassTag[Universe.SingleType]

    A tag that preserves the identity of the SingleType abstract type from erasure.

    A tag that preserves the identity of the SingleType abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  24. implicit abstract val SingletonTypeTag: ClassTag[Universe.SingletonType]

    A tag that preserves the identity of the SingletonType abstract type from erasure.

    A tag that preserves the identity of the SingletonType abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  25. abstract val SuperType: Universe.SuperTypeExtractor

    The constructor/extractor for SuperType instances.

  26. implicit abstract val SuperTypeTag: ClassTag[Universe.SuperType]

    A tag that preserves the identity of the SuperType abstract type from erasure.

    A tag that preserves the identity of the SuperType abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  27. abstract val ThisType: Universe.ThisTypeExtractor

    The constructor/extractor for ThisType instances.

  28. implicit abstract val ThisTypeTag: ClassTag[Universe.ThisType]

    A tag that preserves the identity of the ThisType abstract type from erasure.

    A tag that preserves the identity of the ThisType abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  29. abstract val TypeBounds: Universe.TypeBoundsExtractor

    The constructor/extractor for TypeBounds instances.

  30. implicit abstract val TypeBoundsTag: ClassTag[Universe.TypeBounds]

    A tag that preserves the identity of the TypeBounds abstract type from erasure.

    A tag that preserves the identity of the TypeBounds abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  31. abstract val TypeRef: Universe.TypeRefExtractor

    The constructor/extractor for TypeRef instances.

  32. implicit abstract val TypeRefTag: ClassTag[Universe.TypeRef]

    A tag that preserves the identity of the TypeRef abstract type from erasure.

    A tag that preserves the identity of the TypeRef abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  33. implicit abstract val TypeTagg: ClassTag[Universe.Type]

    A tag that preserves the identity of the Type abstract type from erasure.

    A tag that preserves the identity of the Type abstract type from erasure. Can be used for pattern matching, instance tests, serialization and likes.

    Definition Classes
    ImplicitTags
  34. abstract val WildcardType: Universe.Type

    An object representing an unknown type, used during type inference.

    An object representing an unknown type, used during type inference. If you see WildcardType outside of inference it is almost certainly a bug.

  35. abstract def appliedType(tycon: Universe.Type, args: List[Universe.Type]): Universe.Type

    A creator for type applications

  36. abstract def existentialAbstraction(tparams: List[Universe.Symbol], tpe0: Universe.Type): Universe.Type

    A creator for existential types.

    A creator for existential types. This generates:

    tpe1 where { tparams }

    where tpe1 is the result of extrapolating tpe with regard to tparams. Extrapolating means that type variables in tparams occurring in covariant positions are replaced by upper bounds, (minus any SingletonClass markers), type variables in tparams occurring in contravariant positions are replaced by upper bounds, provided the resulting type is legal with regard to stability, and does not contain any type variable in tparams.

    The abstraction drops all type parameters that are not directly or indirectly referenced by type tpe1. If there are no remaining type parameters, simply returns result type tpe.

  37. abstract def glb(ts: List[Universe.Type]): Universe.Type

    The greatest lower bound of a list of types, as determined by <:<.

  38. abstract def intersectionType(tps: List[Universe.Type], owner: Universe.Symbol): Universe.Type

    A creator for intersection type where intersections of a single type are replaced by the type itself, and repeated parent classes are merged.

    A creator for intersection type where intersections of a single type are replaced by the type itself, and repeated parent classes are merged.

    !!! Repeated parent classes are not merged - is this a bug in the comment or in the code?

  39. abstract def intersectionType(tps: List[Universe.Type]): Universe.Type

    A creator for intersection type where intersections of a single type are replaced by the type itself.

  40. abstract def lub(xs: List[Universe.Type]): Universe.Type

    The least upper bound of a list of types, as determined by <:<.

  41. abstract def polyType(tparams: List[Universe.Symbol], tpe: Universe.Type): Universe.Type

    A creator for type parameterizations that strips empty type parameter lists.

    A creator for type parameterizations that strips empty type parameter lists. Use this factory method to indicate the type has kind * (it's a polymorphic value) until we start tracking explicit kinds equivalent to typeFun (except that the latter requires tparams nonEmpty).

  42. abstract def refinedType(parents: List[Universe.Type], owner: Universe.Symbol): Universe.Type

    The canonical creator for a refined type with an initially empty scope.

  43. abstract def refinedType(parents: List[Universe.Type], owner: Universe.Symbol, decls: Universe.Scope, pos: Universe.Position): Universe.Type

    the canonical creator for a refined type with a given scope

  44. abstract def singleType(pre: Universe.Type, sym: Universe.Symbol): Universe.Type

    The canonical creator for single-types

  45. abstract def typeRef(pre: Universe.Type, sym: Universe.Symbol, args: List[Universe.Type]): Universe.Type

    The canonical creator for typerefs

Concrete Value Members

  1. final def !=(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  2. final def !=(arg0: Any): Boolean

    Definition Classes
    Any
  3. final def ##(): Int

    Definition Classes
    AnyRef → Any
  4. def +(other: String): String

    Implicit information
    This member is added by an implicit conversion from Types to StringAdd[Types] performed by method StringAdd in scala.Predef.
    Definition Classes
    StringAdd
  5. def ->[B](y: B): (Types, B)

    Implicit information
    This member is added by an implicit conversion from Types to ArrowAssoc[Types] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @inline()
  6. final def ==(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  7. final def ==(arg0: Any): Boolean

    Definition Classes
    Any
  8. final def asInstanceOf[T0]: T0

    Definition Classes
    Any
  9. def clone(): AnyRef

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws()
  10. def ensuring(cond: (Types) ⇒ Boolean, msg: ⇒ Any): Types

    Implicit information
    This member is added by an implicit conversion from Types to Ensuring[Types] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  11. def ensuring(cond: (Types) ⇒ Boolean): Types

    Implicit information
    This member is added by an implicit conversion from Types to Ensuring[Types] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  12. def ensuring(cond: Boolean, msg: ⇒ Any): Types

    Implicit information
    This member is added by an implicit conversion from Types to Ensuring[Types] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  13. def ensuring(cond: Boolean): Types

    Implicit information
    This member is added by an implicit conversion from Types to Ensuring[Types] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  14. final def eq(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  15. def equals(arg0: Any): Boolean

    Definition Classes
    AnyRef → Any
  16. def finalize(): Unit

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws()
  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 information
    This member is added by an implicit conversion from Types to StringFormat[Types] performed by method StringFormat in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @inline()
  18. final def getClass(): Class[_]

    Definition Classes
    AnyRef → Any
  19. def hashCode(): Int

    Definition Classes
    AnyRef → Any
  20. final def isInstanceOf[T0]: Boolean

    Definition Classes
    Any
  21. final def ne(arg0: AnyRef): Boolean

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

    Definition Classes
    AnyRef
  23. final def notifyAll(): Unit

    Definition Classes
    AnyRef
  24. final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
    AnyRef
  25. def toString(): String

    Definition Classes
    AnyRef → Any
  26. final def wait(): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws()
  27. final def wait(arg0: Long, arg1: Int): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws()
  28. final def wait(arg0: Long): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws()
  29. def [B](y: B): (Types, B)

    Implicit information
    This member is added by an implicit conversion from Types to ArrowAssoc[Types] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc

Inherited from ImplicitTags

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion StringAdd from Types to StringAdd[Types]

Inherited by implicit conversion StringFormat from Types to StringFormat[Types]

Inherited by implicit conversion Ensuring from Types to Ensuring[Types]

Inherited by implicit conversion ArrowAssoc from Types to ArrowAssoc[Types]

Types - Creation

Types - Operations

Types

API

The methods available for each reflection entity, without the implementation. Since the reflection entities are later overridden by runtime reflection and macros, their API counterparts guarantee a minimum set of methods that are implemented.

Extractors

Extractors provide the machinery necessary to allow pattern matching and construction of reflection entities that is similar to case classes, although the entities are only abstract types that are later overridden.

Tags

Implicit values that provide ClassTags for the reflection classes. These are abstract in the interface but are later filled in to provide ClassTags for the either the runtime reflection or macros entities, depending on the use.

Ungrouped