Add Lift{Value,Kind} instances for Resource

Author: NthPortal

build.sbt

@@ -445,7 +445,8 @@ lazy val kernel = crossProject(JSPlatform, JVMPlatform, NativePlatform)
   .settings(
     name := "cats-effect-kernel",
     libraryDependencies ++= Seq(
-      "org.typelevel" %%% "cats-core" % CatsVersion
+      "org.typelevel" %%% "cats-core" % CatsVersion,
+      "org.typelevel" %%% "cats-mtl" % CatsMtlVersion
     ),
     mimaBinaryIssueFilters ++= Seq(
       ProblemFilters.exclude[MissingClassProblem]("cats.effect.kernel.Ref$SyncRef"),
@@ -501,7 +502,9 @@ lazy val laws = crossProject(JSPlatform, JVMPlatform, NativePlatform)
     name := "cats-effect-laws",
     libraryDependencies ++= Seq(
       "org.typelevel" %%% "cats-laws" % CatsVersion,
-      "org.typelevel" %%% "discipline-munit" % DisciplineMUnitVersion % Test)
+      "org.typelevel" %%% "cats-mtl-laws" % CatsMtlVersion % Test,
+      "org.typelevel" %%% "discipline-munit" % DisciplineMUnitVersion % Test
+    )
   )
 
 /**

kernel/shared/src/main/scala/cats/effect/kernel/Resource.scala

@@ -21,6 +21,7 @@ import cats.data.Kleisli
 import cats.effect.kernel.Resource.Pure
 import cats.effect.kernel.implicits._
 import cats.effect.kernel.instances.spawn
+import cats.mtl.{LiftKind, LiftValue}
 import cats.syntax.all._
 
 import scala.annotation.tailrec
@@ -1275,6 +1276,10 @@ private[effect] trait ResourceHOInstances0 extends ResourceHOInstances1 {
       def K = K0
       def G = G0
     }
+
+  implicit def catsEffectLiftKindForResource[F[_]](
+      implicit F: MonadCancel[F, ?]): LiftKind[F, Resource[F, *]] =
+    liftKindImpl(F)
 }
 
 private[effect] trait ResourceHOInstances1 extends ResourceHOInstances2 {
@@ -1289,6 +1294,25 @@ private[effect] trait ResourceHOInstances1 extends ResourceHOInstances2 {
       def F = F0
       def rootCancelScope = F0.rootCancelScope
     }
+
+  protected[this] def liftKindImpl[F[_]](F: MonadCancel[F, ?]): LiftKind[F, Resource[F, *]] =
+    new LiftKind[F, Resource[F, *]] {
+      implicit val applicativeF: MonadCancel[F, ?] = F
+      val applicativeG: Applicative[Resource[F, *]] = catsEffectMonadForResource
+      def apply[A](fa: F[A]): Resource[F, A] = Resource.eval(fa)
+      def limitedMapK[A](ga: Resource[F, A])(scope: F ~> F): Resource[F, A] =
+        ga.mapK(scope)
+    }
+
+  implicit def catsEffectLiftKindForResourceComposed[F[_], G[_]](
+      implicit inner: LiftKind[F, G],
+      G: MonadCancel[G, ?]
+  ): LiftKind[F, Resource[G, *]] =
+    inner.andThen(liftKindImpl(G))
+
+  implicit def catsEffectLiftValueForResource[F[_]](
+      implicit F: Applicative[F]): LiftValue[F, Resource[F, *]] =
+    liftValueImpl(F)
 }
 
 private[effect] trait ResourceHOInstances2 extends ResourceHOInstances3 {
@@ -1308,6 +1332,18 @@ private[effect] trait ResourceHOInstances2 extends ResourceHOInstances3 {
 
   final implicit def catsEffectDeferForResource[F[_]]: Defer[Resource[F, *]] =
     new ResourceDefer[F]
+
+  protected[this] def liftValueImpl[F[_]](F: Applicative[F]): LiftValue[F, Resource[F, *]] =
+    new LiftValue[F, Resource[F, *]] {
+      val applicativeF: Applicative[F] = F
+      val applicativeG: Applicative[Resource[F, *]] = catsEffectMonadForResource
+      def apply[A](fa: F[A]): Resource[F, A] = Resource.eval(fa)
+    }
+
+  implicit def catsEffectLiftValueForResourceComposed[F[_], G[_]](
+      implicit inner: LiftValue[F, G]
+  ): LiftValue[F, Resource[G, *]] =
+    inner.andThen(liftValueImpl(inner.applicativeG))
 }
 
 private[effect] trait ResourceHOInstances3 extends ResourceHOInstances4 {

laws/shared/src/test/scala/cats/effect/kernel/ResourceSuite.scala

@@ -0,0 +1,82 @@
+package cats
+package effect
+package kernel
+
+import cats.data.OptionT
+import cats.effect.kernel.testkit.PureConcGenerators._
+import cats.effect.kernel.testkit.pure._
+import cats.laws.discipline.arbitrary.catsLawsArbitraryForOptionT
+import cats.mtl.laws.discipline.{LiftKindTests, LiftValueTests}
+import cats.syntax.flatMap._
+import cats.syntax.functor._
+
+import org.scalacheck.{Arbitrary, Gen}
+
+import munit.DisciplineSuite
+
+class ResourceSuite extends DisciplineSuite {
+  type PCT[A] = PureConc[Throwable, A]
+
+  private[this] val counter: PCT[Ref[PCT, Long]] = Concurrent[PCT].ref(0)
+
+  implicit val eqThrowable: Eq[Throwable] = Eq.fromUniversalEquals
+
+  implicit val arbitraryScope: Arbitrary[PCT ~> PCT] =
+    Arbitrary {
+      Gen.const {
+        new (PCT ~> PCT) {
+          def apply[A](fa: PCT[A]): PCT[A] =
+            for {
+              ref <- counter
+              res <- ref.update(_ + 1) >> fa
+            } yield res
+        }
+      }
+    }
+
+  implicit def arbitraryPCTUnit(): Arbitrary[PCT[Unit]] =
+    Arbitrary {
+      Gen.const {
+        counter.flatMap(_.update(_ * 10)).void
+      }
+    }
+
+  implicit def eqResource[F[_], A](
+      implicit F: MonadCancelThrow[F],
+      eqFAUnit: Eq[F[(A, Unit)]]
+  ): Eq[Resource[F, A]] =
+    Eq.by {
+      _.allocated.flatMap {
+        case (acquire, release) =>
+          release.map(acquire -> _)
+      }
+    }
+
+  implicit def arbitraryResource[F[_]: Functor, A](
+      implicit arbFA: Arbitrary[F[A]],
+      arbFUnit: Arbitrary[F[Unit]]
+  ): Arbitrary[Resource[F, A]] =
+    Arbitrary {
+      for {
+        acquire <- arbFA.arbitrary
+        release <- arbFUnit.arbitrary
+      } yield Resource(acquire.map(_ -> release))
+    }
+
+  checkAll(
+    "LiftValue[PureConc, Resource[PureConc, *]]",
+    LiftValueTests[PCT, Resource[PCT, *]].liftValue[Int, Int]
+  )
+  checkAll(
+    "LiftValue[PureConc, Resource[OptionT[PureConc, *], *]]",
+    LiftValueTests[PCT, Resource[OptionT[PCT, *], *]].liftValue[Int, Int]
+  )
+  checkAll(
+    "LiftKind[PureConc, Resource[PureConc, *]]",
+    LiftKindTests[PCT, Resource[PCT, *]].liftKind[Int, Int]
+  )
+  checkAll(
+    "LiftKind[PureConc, Resource[OptionT[PureConc, *], *]]",
+    LiftKindTests[PCT, Resource[OptionT[PCT, *], *]].liftKind[Int, Int]
+  )
+}