鉴于:
abstract class Databases[F[_]]
我怎样才能使这个特征起作用:
// Marker trait signalling the database plugin supports StaticRoles
trait StaticRoles { this: Databases[_] => }
我想确保StaticRoles
只混入也扩展的类中Databases
,但是我不关心类型参数的具体值F
。
代码返回:
error: _$1 takes no type parameters, expected: one
这是公平的,但是它返回相同的错误:
trait StaticRoles { this: Databases[_[_]] => }
我也试过:
trait StaticRoles { this: Databases[({type T[X[_]]})#T] => }
这给出了错误:
error: kinds of the type arguments (AnyRef{type T[X[_]]}#T) do not conform to the expected kinds of the type parameters (type F) in class Databases.
AnyRef{type T[X[_]]}#T's type parameters do not match type F's expected parameters:
type X has one type parameter, but type _ has none