Use kind projector syntax for liftK

typelevel · Nov 22, 2017 · c7f2e99 · c7f2e99
1 parent 49208e0
commit c7f2e99
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Showing 6 changed files with 8 additions and 19 deletions.
diff --git a/core/src/main/scala/cats/data/EitherT.scala b/core/src/main/scala/cats/data/EitherT.scala
@@ -363,9 +363,7 @@ object EitherT extends EitherTInstances {
    * }}}
    */
   final def liftK[F[_], A](implicit F: Functor[F]): F ~> EitherT[F, A, ?] =
-    new (F ~> EitherT[F, A, ?]) {
-      def apply[B](fb: F[B]): EitherT[F, A, B] = right(fb)
-    }
+    λ[F ~> EitherT[F, A, ?]](right(_))
 
   @deprecated("Use EitherT.liftF.", "1.0.0-RC1")
   final def liftT[F[_], A, B](fb: F[B])(implicit F: Functor[F]): EitherT[F, A, B] = right(fb)

diff --git a/core/src/main/scala/cats/data/IndexedReaderWriterStateT.scala b/core/src/main/scala/cats/data/IndexedReaderWriterStateT.scala
@@ -280,9 +280,7 @@ private[data] sealed trait CommonIRWSTConstructors {
    * }}}
    */
   def liftK[F[_], E, L, S](implicit F: Applicative[F], L: Monoid[L]): F ~> IndexedReaderWriterStateT[F, E, L, S, S, ?] =
-    new (F ~> IndexedReaderWriterStateT[F, E, L, S, S, ?]) {
-      def apply[A](fa: F[A]): IndexedReaderWriterStateT[F, E, L, S, S, A] = IndexedReaderWriterStateT.liftF(fa)
-    }
+    λ[F ~> IndexedReaderWriterStateT[F, E, L, S, S, ?]](IndexedReaderWriterStateT.liftF(_))
 
   @deprecated("Use liftF instead", "1.0.0")
   def lift[F[_], E, L, S, A](fa: F[A])(implicit F: Applicative[F], L: Monoid[L]): IndexedReaderWriterStateT[F, E, L, S, S, A] =

diff --git a/core/src/main/scala/cats/data/IndexedStateT.scala b/core/src/main/scala/cats/data/IndexedStateT.scala
@@ -187,9 +187,7 @@ private[data] trait CommonStateTConstructors {
    * }}}
    */
   def liftK[F[_], S](implicit F: Applicative[F]): F ~> IndexedStateT[F, S, S, ?] =
-    new (F ~> IndexedStateT[F, S, S, ?]) {
-      def apply[A](fa: F[A]): IndexedStateT[F, S, S, A] = IndexedStateT.liftF(fa)
-    }
+    λ[F ~> IndexedStateT[F, S, S, ?]](IndexedStateT.liftF(_))
 
   @deprecated("Use liftF instead", "1.0.0")
   def lift[F[_], S, A](fa: F[A])(implicit F: Applicative[F]): IndexedStateT[F, S, S, A] =

diff --git a/core/src/main/scala/cats/data/Kleisli.scala b/core/src/main/scala/cats/data/Kleisli.scala
@@ -97,10 +97,8 @@ private[data] sealed trait KleisliFunctions {
    * res0: Option[Int] = Some(1)
    * }}}
    */
-  def liftK[F[_], A]: F ~> Kleisli[F, A, ?] = new (F ~> Kleisli[F, A, ?]) {
-    def apply[B](x: F[B]): Kleisli[F, A, B] =
-      Kleisli(_ => x)
-  }
+  def liftK[F[_], A]: F ~> Kleisli[F, A, ?] =
+    λ[F ~> Kleisli[F, A, ?]](Kleisli.liftF(_))
 
   @deprecated("Use liftF instead", "1.0.0")
   def lift[F[_], A, B](x: F[B]): Kleisli[F, A, B] =

diff --git a/core/src/main/scala/cats/data/OptionT.scala b/core/src/main/scala/cats/data/OptionT.scala
@@ -209,9 +209,8 @@ object OptionT extends OptionTInstances {
    * res0: Option[Either[String,Int]] = Some(Right(1))
    * }}}
    */
-  def liftK[F[_]](implicit F: Functor[F]): F ~> OptionT[F, ?] = new (F ~> OptionT[F, ?]) {
-      def apply[A](fa: F[A]): OptionT[F, A] = OptionT.liftF(fa)
-    }
+  def liftK[F[_]](implicit F: Functor[F]): F ~> OptionT[F, ?] =
+    λ[F ~> OptionT[F, ?]](OptionT.liftF(_))
 }
 
 private[data] sealed abstract class OptionTInstances extends OptionTInstances0 {

diff --git a/core/src/main/scala/cats/data/WriterT.scala b/core/src/main/scala/cats/data/WriterT.scala
@@ -81,9 +81,7 @@ object WriterT extends WriterTInstances with WriterTFunctions {
    * }}}
    */
   def liftK[F[_], L](implicit monoidL: Monoid[L], F: Applicative[F]): F ~> WriterT[F, L, ?] =
-    new (F ~> WriterT[F, L, ?]) {
-      def apply[V](fa: F[V]): WriterT[F, L, V] = WriterT.liftF(fa)
-    }
+    λ[F ~> WriterT[F, L, ?]](WriterT.liftF(_))
 
   @deprecated("Use liftF instead", "1.0.0")
   def lift[F[_], L, V](fv: F[V])(implicit monoidL: Monoid[L], F: Applicative[F]): WriterT[F, L, V] =