Tags

Type Members

1. trait AnyTag extends AnyRef

   

2. trait HKTag[T] extends AnyTag

   

   Internal unsafe API representing a poly-kinded, higher-kinded type tag.

   Internal unsafe API representing a poly-kinded, higher-kinded type tag.

   To create a Tag* implicit for an arbitrary kind use the following syntax:

   type TagK5[K[_, _, _, _, _]] = HKTag[ { type Arg[A, B, C, D, E] = K[A, B, C, D, E] } ]

   As an argument to HKTag, you should specify the type variables your type parameter will take and apply them to it, in order.

   type TagFGC[K[_[_, _], _[_], _[_[_], _, _, _]] = HKTag[ { type Arg[A[_, _], B[_], C[_[_], _, _, _]] = K[A, B, C] } ]

   A convenience macro Tag.auto.T is available to automatically create a type lambda for a type of any kind:

   def x[K[_[_, _], _[_], _[_[_], _, _, _]: Tag.auto.T]: Tag.auto.T[K] = implicitly[Tag.auto.T[K]]

3. final class HKTagMaterializer[T] extends AnyVal

   

   Force eager expansion for all recursive implicit searches inside TagMacro by introducing a proxy implicit to display better error messages

   Force eager expansion for all recursive implicit searches inside TagMacro by introducing a proxy implicit to display better error messages

   See also

   test ResourceEffectBindingsTest."Display tag macro stack trace when ResourceTag is not found"

4. trait Tag[T] extends AnyTag

   

   Like scala.reflect.api.TypeTags.TypeTag, but supports higher-kinded type tags via TagK type class.

   Like scala.reflect.api.TypeTags.TypeTag, but supports higher-kinded type tags via TagK type class.

   In context of DI this lets you define modules parameterized by higher-kinded type parameters. This is especially helpful for applying tagless final style

   Example:

   class MyModule[F[_]: Monad: TagK] {
     make[MyService[F]]
     make[F[Int]].named("lucky-number").from(Monad[F].pure(7))
   }

   Without a TagK constraint above, this example would fail with no TypeTag available for MyService[F] error

   Currently some limitations apply as to when a Tag will be correctly constructed: * Type Parameters do not yet resolve inside structural refinements, e.g. T in

   Tag[{ def x: T}]

   * TagK* does not resolve for constructors with bounded parameters, e.g. S in

   class Abc[S <: String]; TagK[Abc]

   (You can still have a bound in partial application: e.g.

   class Abc[S <: String, A]; TagK[Abc["hi", ?]]

   * Further details at https://github.com/7mind/izumi/issues/374

   Annotations

   @implicitNotFound( ... )

   See also

   "Lightweight Scala Reflection and why Dotty needs TypeTags reimplemented" https://blog.7mind.io/lightweight-reflection.html

5. type TagK[K[_]] = HKTag[AnyRef { type Arg[A] = K[A] }]

   

   TagK is like a scala.reflect.api.TypeTags.TypeTag but for higher-kinded types.

   TagK is like a scala.reflect.api.TypeTags.TypeTag but for higher-kinded types.

   Example:

   def containerTypesEqual[F[_]: TagK, K[_]: TagK]): Boolean = TagK[F].tag.tpe =:= TagK[K].tag.tpe
   
   containerTypesEqual[Set, collection.immutable.Set] == true
   containerTypesEqual[Array, List] == false

6. type TagK3[K[_, _, _]] = HKTag[AnyRef { type Arg[A, B, C] = K[A,B,C] }]

   

7. type TagKK[K[_, _]] = HKTag[AnyRef { type Arg[A, B] = K[A,B] }]

   

8. type TagT[K[_[_]]] = HKTag[AnyRef { type Arg[A[_]] = K[A] }]

   

9. type TagTK[K[_[_], _]] = HKTag[AnyRef { type Arg[A[_], B] = K[A,B] }]

   

10. type TagTK3[K[_[_], _, _, _]] = HKTag[AnyRef { type Arg[A[_], B, C, D] = K[A,B,C,D] }]

    

11. type TagTKK[K[_[_], _, _]] = HKTag[AnyRef { type Arg[A[_], B, C] = K[A,B,C] }]

    

12. trait WeakTag[T] extends AnyTag

    

13. trait WeakTagInstances1 extends AnyRef