The API that all annotated types support. The main source of information about types is the scala.reflect.api.Types page.
An extractor class to create and pattern match with syntax AnnotatedType(annotations, underlying). Here, annotations are the annotations decorating the underlying type underlying. selfSym is a symbol representing the annotated type itself.
BoundedWildcardTypes, used only during type inference, are created in two places:
The API that all this types support. The main source of information about types is the scala.reflect.api.Types page.
The ClassInfo type signature is used to define parents and declarations of classes, traits, and objects. If a class, trait, or object C is declared like this
C extends P_1 with ... with P_m { D_1; ...; D_n}
its ClassInfo type has the following form:
ClassInfo(List(P_1, ..., P_m), Scope(D_1, ..., D_n), C)
The API that all class info types support. The main source of information about types is the scala.reflect.api.Types page.
Has no special methods. Is here to provides erased identity for CompoundType.
The ConstantType type is not directly written in user programs, but arises as the type of a constant. The REPL expresses constant types like Int(11). Here are some constants with their types:
1 ConstantType(Constant(1))
"abc" ConstantType(Constant("abc"))
The API that all constant types support. The main source of information about types is the scala.reflect.api.Types page.
The API that all existential types support. The main source of information about types is the scala.reflect.api.Types page.
An extractor class to create and pattern match with syntax ExistentialType(quantified, underlying). Here, quantified are the type variables bound by the existential type and underlying is the type that's existentially quantified.
The API that all method types support. The main source of information about types is the scala.reflect.api.Types page.
An extractor class to create and pattern match with syntax MethodType(params, restpe) Here, params is a potentially empty list of parameter symbols of the method, and restpe is the result type of the method. If the method is curried, restpe would be another MethodType. Note: MethodType(Nil, Int) would be the type of a method defined with an empty parameter list.
def f(): Int
If the method is completely parameterless, as in
def f: Int
its type is a NullaryMethodType.
The API that all nullary method types support. The main source of information about types is the scala.reflect.api.Types page.
An extractor class to create and pattern match with syntax NullaryMethodType(resultType). Here, resultType is the result type of the parameterless method.
The API that all polymorphic types support. The main source of information about types is the scala.reflect.api.Types page.
An extractor class to create and pattern match with syntax PolyType(typeParams, resultType). Here, typeParams are the type parameters of the method and resultType is the type signature following the type parameters.
The RefinedType type defines types of any of the forms on the left, with their RefinedType representations to the right.
P_1 with ... with P_m { D_1; ...; D_n} RefinedType(List(P_1, ..., P_m), Scope(D_1, ..., D_n))
P_1 with ... with P_m RefinedType(List(P_1, ..., P_m), Scope())
{ D_1; ...; D_n} RefinedType(List(AnyRef), Scope(D_1, ..., D_n))
The API that all refined types support. The main source of information about types is the scala.reflect.api.Types page.
The SingleType type describes types of any of the forms on the left, with their TypeRef representations to the right.
(T # x).type SingleType(T, x) p.x.type SingleType(p.type, x) x.type SingleType(NoPrefix, x)
The API that all single types support. The main source of information about types is the scala.reflect.api.Types page.
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.
Has no special methods. Is here to provides erased identity for SingletonType.
The SuperType type is not directly written, but arises when C.super is used as a prefix in a TypeRef or SingleType. It's internal presentation is
SuperType(thistpe, supertpe)
Here, thistpe is the type of the corresponding this-type. For instance, in the type arising from C.super, the thistpe part would be ThisType(C). supertpe is the type of the super class referred to by the super.
The API that all super types support. The main source of information about types is the scala.reflect.api.Types page.
A singleton type that describes types of the form on the left with the corresponding ThisType representation to the right:
C.this.type ThisType(C)
The API that all this types support. The main source of information about types is the scala.reflect.api.Types page.
The type of Scala types, and also Scala type signatures. (No difference is internally made between the two).
The API of types. The main source of information about types is the scala.reflect.api.Types page.
The TypeBounds type signature is used to indicate lower and upper type bounds of type parameters and abstract types. It is not a first-class type. If an abstract type or type parameter is declared with any of the forms on the left, its type signature is the TypeBounds type on the right.
T >: L <: U TypeBounds(L, U) T >: L TypeBounds(L, Any) T <: U TypeBounds(Nothing, U)
The API that all type bounds support. The main source of information about types is the scala.reflect.api.Types page.
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)
The API that all type refs support. The main source of information about types is the scala.reflect.api.Types page.
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.
An object representing an unknown type, used during type inference. If you see WildcardType outside of inference it is almost certainly a bug.
© 2002-2019 EPFL, with contributions from Lightbend.
Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.12.9/scala-reflect/scala/reflect/api/Types.html
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
Typeinstance which represents that argument. For example:In this example, a scala.reflect.api.Types#TypeRef is returned, which corresponds to the type constructor
Listapplied to the type argumentInt.Note: Method
typeOfdoes not work for types with type parameters, such astypeOf[List[A]]whereAis 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.
<:<andweak_<:<.=:=. 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
membersanddeclarationsmethods (along with their singular counterpartsmemberanddeclaration), which provide the list of definitions associated with that type. For example, to look up themapmethod ofList, one can do:scala> typeOf[List[_]].member("map": TermName) res1: reflect.runtime.universe.Symbol = method mapFor more information about
Types, see the Reflection Guide: Symbols, Trees, and Types