Merge pull request #154 from johnhungerford/add-layers

Add Layer trait and Layer factory methods on Envs, Aborts, Tries, and Options

kyo-core/shared/src/main/scala/kyo/aborts.scala

@@ -10,6 +10,7 @@ import scala.util.Success
 import kyo._
 import core._
 import tries._
+import layers._
 import scala.util.Try
 
 object aborts {
@@ -28,7 +29,7 @@ object aborts {
   }
 
   final class Aborts[E] private[aborts] (private val tag: Tag[E])
-      extends Effect[Abort[E]#Value, Aborts[E]] {
+      extends Effect[Abort[E]#Value, Aborts[E]] { self =>
 
     private implicit def _tag: Tag[E] = tag
 
@@ -91,5 +92,19 @@ object aborts {
       }
 
     override def toString = s"Aborts[${tag.tag.longNameWithPrefix}]"
+
+    def layer[Se](handle: E => Nothing > Se): Layer[Aborts[E], Se] =
+      new Layer[Aborts[E], Se] {
+        override def run[T, S](
+            effect: T > (Aborts[E] with S)
+        )(
+            implicit flat: Flat[T > (Aborts[E] with S)]
+        ): T > (S with Se) =
+          self.run[T, S](effect)(flat).map {
+            case Left(err) => handle(err)
+            case Right(t)  => t
+          }
+      }
   }
+
 }

kyo-core/shared/src/main/scala/kyo/envs.scala

@@ -5,6 +5,7 @@ import izumi.reflect._
 import scala.reflect.ClassTag
 
 import kyo.core._
+import kyo.layers.Layer
 
 object envs {
 
@@ -15,7 +16,7 @@ object envs {
   }
 
   final class Envs[E] private[envs] (implicit private val tag: Tag[_])
-      extends Effect[Env[E]#Value, Envs[E]] {
+      extends Effect[Env[E]#Value, Envs[E]] { self =>
 
     val get: E > Envs[E] =
       suspend(Input.asInstanceOf[Env[E]#Value[E]])
@@ -47,6 +48,14 @@ object envs {
       }
 
     override def toString = s"Envs[${tag.tag.longNameWithPrefix}]"
+
+    def layer[Sd](construct: E > Sd): Layer[Envs[E], Sd] =
+      new Layer[Envs[E], Sd] {
+        override def run[T, S](effect: T > (Envs[E] with S))(implicit
+            fl: Flat[T > (Envs[E] with S)]
+        ): T > (Sd with S) =
+          construct.map(e => self.run[T, S](e)(effect))
+      }
   }
 
   object Envs {

kyo-core/shared/src/main/scala/kyo/layers.scala

@@ -0,0 +1,131 @@
+package kyo
+
+object layers {
+
+  trait Layer[In, Out] { self =>
+    def run[T, S](effect: T > (In with S))(implicit fl: Flat[T > (In with S)]): T > (S with Out)
+
+    final def andThen[Out1, In1](other: Layer[In1, Out1]): Layer[In with In1, Out with Out1] =
+      new Layer[In with In1, Out with Out1] {
+        override def run[T, S](
+            effect: T > (In with In1 with S)
+        )(
+            implicit fl: Flat[T > (In with In1 with S)]
+        ): T > (S with Out with Out1) = {
+          val selfRun: T > (In1 with Out with S) =
+            self.run[T, S with In1](effect: T > (In1 with In with S))
+          val otherRun: T > (Out with Out1 with S) =
+            other.run[T, S with Out](selfRun)(Flat.unsafe.unchecked)
+          otherRun
+        }
+      }
+
+    final def chain[In2, Out2](other: Layer[In2, Out2])(
+        implicit ap: ChainLayer[Out, In2]
+    ): Layer[In, Out2 with ap.RemainingOut1] = {
+      ap.applyLayer[In, Out2](self, other)
+    }
+  }
+
+  sealed trait ChainLayer[Out1, In2] {
+    type RemainingOut1
+
+    def applyLayer[In1, Out2](
+        layer1: Layer[In1, Out1],
+        layer2: Layer[In2, Out2]
+    ): Layer[In1, RemainingOut1 with Out2]
+  }
+
+  trait ChainLayers2 {
+    implicit def application[Out1, Shared, In2]
+        : ChainLayer.Aux[Out1 with Shared, In2 with Shared, Out1] =
+      new ChainLayer[Out1 with Shared, In2 with Shared] {
+        type RemainingOut1 = Out1
+        override def applyLayer[In1, Out2](
+            layer1: Layer[In1, Out1 with Shared],
+            layer2: Layer[In2 with Shared, Out2]
+        ): Layer[In1, Out1 with Out2] =
+          new Layer[In1, Out1 with Out2] {
+            override def run[T, S](effect: T > (In1 with S))(implicit
+                fl: Flat[T > (In1 with S)]
+            ): T > (S with Out2 with Out1) = {
+              val handled1: T > (S with Out1 with Shared) = layer1.run[T, S](effect)
+              val handled2: T > (S with Out2 with Out1) =
+                layer2.run[T, S with Out1](handled1)(Flat.unsafe.unchecked)
+              handled2
+            }
+          }
+
+      }
+  }
+
+  trait ChainLayers1 {
+    implicit def applyAll1[Shared, In2]: ChainLayer.Aux[Shared, In2 with Shared, Any] =
+      new ChainLayer[Shared, In2 with Shared] {
+        type RemainingOut1 = Any
+
+        override def applyLayer[In1, Out2](
+            layer1: Layer[In1, Shared],
+            layer2: Layer[In2 with Shared, Out2]
+        ): Layer[In1, Out2] =
+          new Layer[In1, Out2] {
+            override def run[T, S](effect: T > (In1 with S))(implicit
+                fl: Flat[T > (In1 with S)]
+            ): T > (S with Out2) = {
+              val handled1: T > (S with Shared) = layer1.run[T, S](effect)
+              val handled2: T > (S with Out2) =
+                layer2.run[T, S](handled1)(Flat.unsafe.unchecked)
+              handled2
+            }
+          }
+
+      }
+
+    implicit def applyAll2[Out1, Shared]: ChainLayer.Aux[Out1 with Shared, Shared, Out1] =
+      new ChainLayer[Out1 with Shared, Shared] {
+        type RemainingOut1 = Out1
+
+        override def applyLayer[In1, Out2](
+            layer1: Layer[In1, Out1 with Shared],
+            layer2: Layer[Shared, Out2]
+        ): Layer[In1, Out1 with Out2] =
+          new Layer[In1, Out1 with Out2] {
+            override def run[T, S](effect: T > (In1 with S))(implicit
+                fl: Flat[T > (In1 with S)]
+            ): T > (S with Out1 with Out2) = {
+              val handled1: T > (S with Out1 with Shared) = layer1.run[T, S](effect)
+              val handled2: T > (S with Out1 with Out2) =
+                layer2.run[T, S with Out1](handled1)(Flat.unsafe.unchecked)
+              handled2
+            }
+          }
+
+      }
+  }
+
+  object ChainLayer extends ChainLayers1 {
+    type Aux[Out1, In2, R] = ChainLayer[Out1, In2] { type RemainingOut1 = R }
+
+    implicit def simpleChain[Out]: ChainLayer.Aux[Out, Out, Any] =
+      new ChainLayer[Out, Out] {
+        type RemainingOut1 = Any
+
+        override def applyLayer[In1, Out2](
+            layer1: Layer[In1, Out],
+            layer2: Layer[Out, Out2]
+        ): Layer[In1, Any with Out2] =
+          new Layer[In1, Any with Out2] {
+            override def run[T, S](effect: T > (In1 with S))(implicit
+                fl: Flat[T > (In1 with S)]
+            ): T > (S with Out2) = {
+              val handled1: T > (Out with S) = layer1.run[T, S](effect)
+              val handled2: T > (S with Out2) =
+                layer2.run[T, S](handled1)(Flat.unsafe.unchecked)
+              handled2
+            }
+          }
+
+      }
+  }
+
+}

kyo-core/shared/src/main/scala/kyo/options.scala

@@ -1,6 +1,7 @@
 package kyo
 
 import kyo.aborts._
+import kyo.layers._
 
 object options {
 
@@ -50,5 +51,16 @@ object options {
             case v    => get(v)
           }
       }
+
+    def layer[Se](onEmpty: => Nothing > Se): Layer[Options, Se] =
+      new Layer[Options, Se] {
+        override def run[T, S](effect: T > (Options with S))(implicit
+            fl: Flat[T > (Options with S)]
+        ): T > (S with Se) =
+          Options.run[T, S](effect).map {
+            case None    => onEmpty
+            case Some(t) => t
+          }
+      }
   }
 }

kyo-core/shared/src/main/scala/kyo/tries.scala

@@ -1,6 +1,7 @@
 package kyo
 
 import kyo.aborts._
+import kyo.layers._
 
 import scala.util._
 
@@ -43,5 +44,16 @@ object tries {
         case Failure(ex) =>
           fail(ex)
       }
+
+    def layer[Se](handle: Throwable => Nothing > Se): Layer[Tries, Se] =
+      new Layer[Tries, Se] {
+        override def run[T, S](effect: T > (Tries with S))(implicit
+            fl: Flat[T > (Tries with S)]
+        ): T > (S with Se) =
+          Tries.run[T, S](effect).map {
+            case Failure(exception) => handle(exception)
+            case Success(t)         => t
+          }
+      }
   }
 }

kyo-core/shared/src/test/scala/kyoTest/layersTest.scala

@@ -0,0 +1,120 @@
+package kyoTest
+
+import kyo._
+import kyo.envs._
+import kyo.aborts._
+import kyo.tries._
+import kyo.options._
+import kyo.layers._
+import scala.util.Failure
+
+class layersTest extends KyoTest {
+
+  final case class Dep1(int: Int)
+  final case class Dep2(str: String)
+  final case class Dep3(bool: Boolean)
+
+  final case class Dep(dep1: Int, dep2: String, dep3: Boolean)
+
+  val depLayer  = Envs[Dep].layer(Dep(1, "hello", true))
+  val dep1Layer = Envs[Dep1].layer(Envs[Dep].get.map(v => Dep1(v.dep1)))
+  val dep2Layer = Envs[Dep2].layer(Envs[Dep].get.map(v => Dep2(v.dep2)))
+  val dep3Layer = Envs[Dep3].layer(Envs[Dep].get.map(v => Dep3(v.dep3)))
+
+  "Envs layers should be composable and provide multiple dependencies" in {
+    val layer = (dep1Layer andThen dep2Layer andThen dep3Layer) chain depLayer
+
+    val effect = for {
+      dep1 <- Envs[Dep1].get
+      dep2 <- Envs[Dep2].get
+      dep3 <- Envs[Dep3].get
+    } yield s"${dep1.int}-${dep2.str}-${dep3.bool}"
+
+    val handledEffect = layer.run(effect)
+
+    assert(handledEffect == "1-hello-true")
+  }
+
+  final case class TestError1(msg: String)
+  final case class TestError2(msg: String)
+  val stringToTE1Layer = Aborts[String].layer(str => Aborts[TestError1].fail(TestError1(str)))
+  val dep1ToTE1Layer   = Aborts[Dep2].layer(dep => Aborts[TestError1].fail(TestError1(dep.str)))
+  val throwableToTE1Layer =
+    Aborts[Throwable].layer(err => Aborts[TestError1].fail(TestError1(err.getMessage())))
+  val testError1ToTE2Layer =
+    Aborts[TestError1].layer(err => Aborts[TestError2].fail(TestError2(err.msg)))
+
+  "Aborts layers should be composable and handle multiple error types" in {
+    val layer =
+      (stringToTE1Layer andThen dep1ToTE1Layer andThen throwableToTE1Layer) chain testError1ToTE2Layer
+
+    val effect1 = for {
+      _ <- Aborts[String].fail("string failure")
+      _ <- Aborts[Dep2].fail(Dep2("dep2 failure"))
+      _ <- Aborts[Throwable].fail(new Exception("throwable failure"))
+    } yield ()
+
+    val effect2 = for {
+      _ <- Aborts[Throwable].fail(new Exception("throwable failure"))
+      _ <- Aborts[String].fail("string failure")
+      _ <- Aborts[Dep2].fail(Dep2("dep2 failure"))
+    } yield ()
+
+    val effect3 = for {
+      _ <- Aborts[Dep2].fail(Dep2("dep2 failure"))
+      _ <- Aborts[Throwable].fail(new Exception("throwable failure"))
+      _ <- Aborts[String].fail("string failure")
+    } yield ()
+
+    assert(Aborts[TestError2].run(layer.run(effect1)) == Left(TestError2("string failure")))
+    assert(Aborts[TestError2].run(layer.run(effect2)) == Left(TestError2("throwable failure")))
+    assert(Aborts[TestError2].run(layer.run(effect3)) == Left(TestError2("dep2 failure")))
+  }
+
+  val triesToAbortsLayer  = Tries.layer(err => Aborts[Throwable].fail(err))
+  val triesToOptionsLayer = Tries.layer(_ => Options.get(None))
+
+  "Tries layer should handle tries as other failures" in {
+    val effect = for {
+      _ <- Tries.fail("fail")
+    } yield ()
+
+    val effectHandledToAborts  = triesToAbortsLayer.run(effect)
+    val effectHandledToOptions = triesToOptionsLayer.run(effect)
+
+    assert {
+      Aborts[Throwable].run(effectHandledToAborts) match {
+        case Left(err: Throwable) => err.getMessage == "fail"
+        case _                    => false
+      }
+    }
+    assert(Options.run(effectHandledToOptions) == None)
+  }
+
+  val optionsToAbortsLayer = Options.layer(Aborts[String].fail("missing value"))
+  val optionsToTriesLayer  = Options.layer(Tries.fail("missing value"))
+
+  "Options layer should handle None as other failures" in {
+    val effect = for {
+      _ <- Options.get(None)
+    } yield ()
+
+    val effectHandledToAborts = optionsToAbortsLayer.run(effect)
+    val effectHandledToTries  = optionsToTriesLayer.run(effect)
+
+    assert {
+      Aborts[String].run(effectHandledToAborts) match {
+        case Left("missing value") => true
+        case _                     => false
+      }
+    }
+
+    assert {
+      Tries.run(effectHandledToTries) match {
+        case Failure(err: Throwable) => err.getMessage == "missing value"
+        case _                       => false
+      }
+    }
+  }
+
+}