The AnnotatedType type signature is used for annotated types of the
for <type> @<annotation>.
The API that all annotated types support.
An extractor class to create and pattern match with syntax
AnnotatedType(annotations, underlying, selfsym).
BoundedWildcardTypes, used only during type inference, are created in two places:
The API that all this types support.
An extractor class to create and pattern match with syntax BoundedWildcardTypeExtractor(bounds)
with bounds denoting the type bounds.
The ClassInfo type signature is used to define parents and declarations
of classes, traits, and objects.
The API that all class info types support.
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.
A subtype of Type representing refined types as well as ClassInfo signatures.
The ConstantType type is not directly written in user programs, but arises as the type of a constant.
The API that all constant types support.
An extractor class to create and pattern match with syntax ConstantType(constant)
Here, constant is the constant value represented by the type.
The ExistentialType type signature is used for existential types and
wildcard types.
The API that all existential types support.
An extractor class to create and pattern match with syntax
ExistentialType(quantified, underlying).
The MethodType type signature is used to indicate parameters and result type of a method
The API that all method types support.
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.
The NullaryMethodType type signature is used for parameterless methods
with declarations of the form def foo: T
The API that all nullary method types support.
An extractor class to create and pattern match with syntax NullaryMethodType(resultType).
The PolyType type signature is used for polymorphic methods
that have at least one type parameter.
The API that all polymorphic types support.
An extractor class to create and pattern match with syntax PolyType(typeParams, resultType).
The RefinedType type defines types of any of the forms on the left,
with their RefinedType representations to the right.
The API that all refined types support.
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.
The SingleType type describes types of any of the forms on the left,
with their TypeRef representations to the right.
The API that all single types support.
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.
The type of Scala singleton types, i.
The SuperType type is not directly written, but arises when C.super is used
as a prefix in a TypeRef or SingleType.
The API that all super types support.
An extractor class to create and pattern match with syntax SingleType(thistpe, supertpe)
A singleton type that describes types of the form on the left with the
corresponding ThisType representation to the right:
The API that all this types support.
An extractor class to create and pattern match with syntax ThisType(sym)
where sym is the class prefix of the this type.
The type of Scala types, and also Scala type signatures.
The API of types.
The TypeBounds type signature is used to indicate lower and upper type bounds
of type parameters and abstract types.
The API that all type bounds support.
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.
The TypeRef type describes types of any of the forms on the left,
with their TypeRef representations to the right.
The API that all type refs support.
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.
The constructor/extractor for AnnotatedType instances.
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.
The constructor/extractor for BoundedWildcardType instances.
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.
The constructor/extractor for ClassInfoType instances.
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.
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.
The constructor/extractor for ConstantType instances.
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.
The constructor/extractor for ExistentialType instances.
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.
The constructor/extractor for MethodType instances.
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.
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.
This constant is used as a special value that indicates that no meaningful type exists.
The constructor/extractor for NullaryMethodType instances.
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.
The constructor/extractor for PolyType instances.
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.
The constructor/extractor for RefinedType instances.
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.
The constructor/extractor for SingleType instances.
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.
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.
The constructor/extractor for SuperType instances.
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.
The constructor/extractor for ThisType instances.
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.
The constructor/extractor for TypeBounds instances.
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.
The constructor/extractor for TypeRef instances.
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.
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.
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.
A creator for type applications
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.
The greatest lower bound of a list of types, as determined by <:<.
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?
A creator for intersection type where intersections of a single type are replaced by the type itself.
The least upper bound of a list of types, as determined by <:<.
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).
The canonical creator for a refined type with an initially empty scope.
the canonical creator for a refined type with a given scope
The canonical creator for single-types
The canonical creator for typerefs
Test two objects for inequality.
Test two objects for inequality.
true if !(this == that), false otherwise.
Equivalent to x.hashCode except for boxed numeric types and null.
Equivalent to x.hashCode except for boxed numeric types and null.
For numerics, it returns a hash value which is consistent
with value equality: if two value type instances compare
as true, then ## will produce the same hash value for each
of them.
For null returns a hashcode where null.hashCode throws a
NullPointerException.
a hash value consistent with ==
Test two objects for equality.
Test two objects for equality.
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
true if the receiver object is equivalent to the argument; false otherwise.
Cast the receiver object to be of type T0.
Cast the receiver object to be of type T0.
Note that the success of a cast at runtime is modulo Scala's erasure semantics.
Therefore the expression 1.asInstanceOf[String] will throw a ClassCastException at
runtime, while the expression List(1).asInstanceOf[List[String]] will not.
In the latter example, because the type argument is erased as part of compilation it is
not possible to check whether the contents of the list are of the requested type.
the receiver object.
if the receiver object is not an instance of the erasure of type T0.
Create a copy of the receiver object.
Tests whether the argument (arg0) is a reference to the receiver object (this).
Tests whether the argument (arg0) is a reference to the receiver object (this).
The eq method implements an equivalence relation on
non-null instances of AnyRef, and has three additional properties:
x and y of type AnyRef, multiple invocations of
x.eq(y) consistently returns true or consistently returns false.x of type AnyRef, x.eq(null) and null.eq(x) returns false.null.eq(null) returns true. When overriding the equals or hashCode methods, it is important to ensure that their behavior is
consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they
should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).
true if the argument is a reference to the receiver object; false otherwise.
The equality method for reference types.
Called by the garbage collector on the receiver object when there are no more references to the object.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the finalize method is invoked, as
well as the interaction between finalize and non-local returns
and exceptions, are all platform dependent.
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).
A representation that corresponds to the dynamic class of the receiver object.
A representation that corresponds to the dynamic class of the receiver object.
The nature of the representation is platform dependent.
a representation that corresponds to the dynamic class of the receiver object.
not specified by SLS as a member of AnyRef
The hashCode method for reference types.
Test whether the dynamic type of the receiver object is T0.
Test whether the dynamic type of the receiver object is T0.
Note that the result of the test is modulo Scala's erasure semantics.
Therefore the expression 1.isInstanceOf[String] will return false, while the
expression List(1).isInstanceOf[List[String]] will return true.
In the latter example, because the type argument is erased as part of compilation it is
not possible to check whether the contents of the list are of the specified type.
true if the receiver object is an instance of erasure of type T0; false otherwise.
Equivalent to !(this eq that).
Equivalent to !(this eq that).
true if the argument is not a reference to the receiver object; false otherwise.
Wakes up a single thread that is waiting on the receiver object's monitor.
Wakes up a single thread that is waiting on the receiver object's monitor.
not specified by SLS as a member of AnyRef
Wakes up all threads that are waiting on the receiver object's monitor.
Wakes up all threads that are waiting on the receiver object's monitor.
not specified by SLS as a member of AnyRef
Creates a String representation of this object.
Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.
a String representation of the object.
(types: StringAdd).self
(types: StringFormat).self
(types: ArrowAssoc[Types]).x
(Since version 2.10.0) Use leftOfArrow instead
(types: Ensuring[Types]).x
(Since version 2.10.0) Use resultOfEnsuring instead
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 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.
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.
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:For more information about
Types, see the Reflection Guide: Symbols, Trees, and Types