Fix ambiguous Const instances and add missing instances
#4458
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armanbilge
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Const instances and add missing instances
| @nowarn("cat=unused") | ||
| def traverse[F[_], C](f: B => F[C])(implicit F: Applicative[F]): F[Const[A, C]] = | ||
| F.pure(retag[C]) |
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Just a hint (feel free to disregard): with help of scalac-compat it can be addressed in a nicer way:
import org.typelevel.scalaccompat.annotation._
then
| @nowarn("cat=unused") | |
| def traverse[F[_], C](f: B => F[C])(implicit F: Applicative[F]): F[Const[A, C]] = | |
| F.pure(retag[C]) | |
| def traverse[F[_], C](@unused f: B => F[C])(implicit F: Applicative[F]): F[Const[A, C]] = | |
| F.pure(retag[C]) |
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[error] ../typelevel/cats/core/src/main/scala/cats/data/Const.scala:26:12: object typelevel is not a member of package org
[error] import org.typelevel.scalaccompat.annotation._
[error] ^
[error] ../typelevel/cats/core/src/main/scala/cats/data/Const.scala:46:26: not found: type unused
[error] def traverse[F[_], C](@unused f: B => F[C])(implicit F: Applicative[F]): F[Const[A, C]] =
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Yeah, I guess it should work better once these changes (typelevel/sbt-typelevel#518) will be available in the current version of the plugin 🤷
Meanwhile you could add it to build.sbt temporarily:
ThisBuild / libraryDependencies += "org.typelevel" %% "scalac-compat-annotation" % "0.1.0" % CompileTime... or skip my initial comment about it entirely ...
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We have a lot of unused (and other) warnings in the project. I guess it would be good to tackle them together.
Cannot find those in your changes 🤔 |
Ah yes, I fixed the ambiguity of |
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| implicit def catsDataFunctorForConst[C]: Functor[Const[C, *]] = | ||
| @deprecated("Use catsDataTraverseForConst instead", "2.10.0") |
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I think we might want to override map in catsDataTraverseForConst, for Performance:tm:. Or, so long as we are keeping ConstFunctor, we can extend from it to inherit the specialized implementation.
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I made it final override because it was also overridden in ConstApplicative
- Reorder instances in `Const` systematically - Fix ambiguous `InvariantMonoidal` instance - Add `ContravariantSemigroupal` instance - Deprecate unnecessary `Functor` instance - Add `Hash` instance and `hash` method - Add `SemigroupK` and `MonoidK` instances
- Both `Traverse` and `Applicative` have a default `map` implementation - Trait linearization determines which `map` method is called - Make `map` in `ConstFunctor` final override to make sure
ConstsystematicallyInvariantMonoidalinstanceContravariantSemigroupalinstanceFunctorinstanceHashinstance andhashmethodSemigroupKandMonoidKinstances