Change return type of raise to Nothing (#2839)

* Change return type of raise to Nothing Implements #2805 * Update public api with ./gradlew apiDump * Suppress warnings for unreachable calls to fail in tests The test is verifying that no code will be executed after a call to raise, so it's actually testing the very behaviour that the compiler is warning us about. Co-authored-by: Alejandro Serrano <[email protected]>
arrow-kt · Nov 17, 2022 · 47b06a6 · 47b06a6
1 parent 5a03760
commit 47b06a6
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diff --git a/arrow-libs/core/arrow-core/api/arrow-core.api b/arrow-libs/core/arrow-core/api/arrow-core.api
@@ -2598,7 +2598,7 @@ public final class arrow/core/continuations/DefaultRaise : arrow/core/continuati
 	public fun catch (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public fun invoke (Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public fun invoke (Lkotlin/jvm/functions/Function2;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
-	public fun raise (Ljava/lang/Object;)Ljava/lang/Object;
+	public fun raise (Ljava/lang/Object;)Ljava/lang/Void;
 	public fun recover (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function2;)Ljava/lang/Object;
 	public fun recover (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public fun recover (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@@ -2619,7 +2619,7 @@ public final class arrow/core/continuations/DefaultStateRaise : arrow/atomic/Ato
 	public fun getValue ()Ljava/lang/Object;
 	public fun invoke (Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public fun invoke (Lkotlin/jvm/functions/Function2;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
-	public fun raise (Ljava/lang/Object;)Ljava/lang/Object;
+	public fun raise (Ljava/lang/Object;)Ljava/lang/Void;
 	public fun recover (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function2;)Ljava/lang/Object;
 	public fun recover (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public fun recover (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@@ -2688,7 +2688,7 @@ public final class arrow/core/continuations/IorRaise : arrow/core/continuations/
 	public fun invoke (Lkotlin/jvm/functions/Function2;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public fun maybeCombine (Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
 	public fun plus (Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
-	public fun raise (Ljava/lang/Object;)Ljava/lang/Object;
+	public fun raise (Ljava/lang/Object;)Ljava/lang/Void;
 	public fun recover (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function2;)Ljava/lang/Object;
 	public fun recover (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public fun recover (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@@ -2726,9 +2726,9 @@ public final class arrow/core/continuations/NullableRaise : arrow/core/continuat
 	public fun invoke (Lkotlin/jvm/functions/Function2;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public static fun invoke-impl (Larrow/core/continuations/Raise;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public static fun invoke-impl (Larrow/core/continuations/Raise;Lkotlin/jvm/functions/Function2;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
-	public synthetic fun raise (Ljava/lang/Object;)Ljava/lang/Object;
-	public fun raise (Ljava/lang/Void;)Ljava/lang/Object;
-	public static fun raise-impl (Larrow/core/continuations/Raise;Ljava/lang/Void;)Ljava/lang/Object;
+	public synthetic fun raise (Ljava/lang/Object;)Ljava/lang/Void;
+	public fun raise (Ljava/lang/Void;)Ljava/lang/Void;
+	public static fun raise-impl (Larrow/core/continuations/Raise;Ljava/lang/Void;)Ljava/lang/Void;
 	public fun recover (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function2;)Ljava/lang/Object;
 	public fun recover (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public fun recover (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@@ -2771,9 +2771,9 @@ public final class arrow/core/continuations/OptionRaise : arrow/core/continuatio
 	public fun invoke (Lkotlin/jvm/functions/Function2;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public static fun invoke-impl (Larrow/core/continuations/Raise;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public static fun invoke-impl (Larrow/core/continuations/Raise;Lkotlin/jvm/functions/Function2;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
-	public fun raise (Larrow/core/None;)Ljava/lang/Object;
-	public synthetic fun raise (Ljava/lang/Object;)Ljava/lang/Object;
-	public static fun raise-impl (Larrow/core/continuations/Raise;Larrow/core/None;)Ljava/lang/Object;
+	public fun raise (Larrow/core/None;)Ljava/lang/Void;
+	public synthetic fun raise (Ljava/lang/Object;)Ljava/lang/Void;
+	public static fun raise-impl (Larrow/core/continuations/Raise;Larrow/core/None;)Ljava/lang/Void;
 	public fun recover (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function2;)Ljava/lang/Object;
 	public fun recover (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public fun recover (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@@ -2796,7 +2796,7 @@ public abstract interface class arrow/core/continuations/Raise {
 	public abstract fun catch (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public abstract fun invoke (Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public abstract fun invoke (Lkotlin/jvm/functions/Function2;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
-	public abstract fun raise (Ljava/lang/Object;)Ljava/lang/Object;
+	public abstract fun raise (Ljava/lang/Object;)Ljava/lang/Void;
 	public abstract fun recover (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function2;)Ljava/lang/Object;
 	public abstract fun recover (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public abstract fun recover (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@@ -2855,9 +2855,9 @@ public final class arrow/core/continuations/ResultRaise : arrow/core/continuatio
 	public fun invoke (Lkotlin/jvm/functions/Function2;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public static fun invoke-impl (Larrow/core/continuations/Raise;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public static fun invoke-impl (Larrow/core/continuations/Raise;Lkotlin/jvm/functions/Function2;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
-	public synthetic fun raise (Ljava/lang/Object;)Ljava/lang/Object;
-	public fun raise (Ljava/lang/Throwable;)Ljava/lang/Object;
-	public static fun raise-impl (Larrow/core/continuations/Raise;Ljava/lang/Throwable;)Ljava/lang/Object;
+	public synthetic fun raise (Ljava/lang/Object;)Ljava/lang/Void;
+	public fun raise (Ljava/lang/Throwable;)Ljava/lang/Void;
+	public static fun raise-impl (Larrow/core/continuations/Raise;Ljava/lang/Throwable;)Ljava/lang/Void;
 	public fun recover (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function2;)Ljava/lang/Object;
 	public fun recover (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public fun recover (Lkotlin/jvm/functions/Function2;Lkotlin/jvm/functions/Function3;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;

diff --git a/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/continuations/Builders.kt b/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/continuations/Builders.kt
@@ -46,7 +46,7 @@ public inline fun <E, A> ior(semigroup: Semigroup<E>, @BuilderInference action:
 public value class NullableRaise(private val cont: Raise<Nothing?>) : Raise<Nothing?> {
   @EffectDSL
   public fun ensure(value: Boolean): Unit = ensure(value) { null }
-  override fun <B> raise(r: Nothing?): B = cont.raise(r)
+  override fun raise(r: Nothing?): Nothing = cont.raise(r)
   public fun <B> Option<B>.bind(): B = bind { raise(null) }
 
   public fun <B> B?.bind(): B {
@@ -62,13 +62,13 @@ public value class NullableRaise(private val cont: Raise<Nothing?>) : Raise<Noth
 
 @JvmInline
 public value class ResultRaise(private val cont: Raise<Throwable>) : Raise<Throwable> {
-  override fun <B> raise(r: Throwable): B = cont.raise(r)
+  override fun raise(r: Throwable): Nothing = cont.raise(r)
   public fun <B> Result<B>.bind(): B = fold(::identity) { raise(it) }
 }
 
 @JvmInline
 public value class OptionRaise(private val cont: Raise<None>) : Raise<None> {
-  override fun <B> raise(r: None): B = cont.raise(r)
+  override fun raise(r: None): Nothing = cont.raise(r)
   public fun <B> Option<B>.bind(): B = bind { raise(None) }
   public fun ensure(value: Boolean): Unit = ensure(value) { None }
 
@@ -83,8 +83,8 @@ public class IorRaise<E> @PublishedApi internal constructor(
   @PublishedApi
   internal val effect: StateRaise<Option<E>, E>,
 ) : Raise<E>, Semigroup<E> by semigroup {
-  
-  override fun <B> raise(r: E): B = effect.raise(combine(r))
+
+  override fun raise(r: E): Nothing = effect.raise(combine(r))
 
   public fun <B> Ior<E, B>.bind(): B =
     when (this) {

diff --git a/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/continuations/Effect.kt b/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/continuations/Effect.kt
@@ -355,7 +355,7 @@ import kotlin.jvm.JvmMultifileClass
  *    val error = "Error"
  *    val exit = CompletableDeferred<ExitCase>()
  *   effect<String, Int> {
- *     parZip({ awaitExitCase<Int>(exit) }, { raise<Int>(error) }) { a, b -> a + b }
+ *     parZip({ awaitExitCase<Int>(exit) }, { raise(error) }) { a: Int, b: Int -> a + b }
  *   }.fold({ it shouldBe error }, { fail("Int can never be the result") })
  *   exit.await().shouldBeTypeOf<ExitCase>()
  * }
@@ -425,7 +425,7 @@ import kotlin.jvm.JvmMultifileClass
  *   val error = "Error"
  *   val exit = CompletableDeferred<ExitCase>()
  *   effect<String, Int> {
- *     raceN({ awaitExitCase<Int>(exit) }) { raise<Int>(error) }
+ *     raceN({ awaitExitCase<Int>(exit) }) { raise(error) }
  *       .merge() // Flatten Either<Int, Int> result from race into Int
  *   }.fold({ msg -> msg shouldBe error }, { fail("Int can never be the result") })
  *   // It's possible not all parallel task got launched, and in those cases awaitCancellation never ran
@@ -497,7 +497,7 @@ import kotlin.jvm.JvmMultifileClass
  *   resourceScope {
  *     effect<String, Int> {
  *       val reader = bufferedReader("build.gradle.kts")
- *       raise<Int>(error)
+ *       raise(error)
  *       reader.lineSequence().count()
  *     }.fold({ it shouldBe error }, { fail("Int can never be the result") })
  *   }

diff --git a/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/continuations/Fold.kt b/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/continuations/Fold.kt
@@ -72,7 +72,7 @@ internal fun <R> CancellationException.raisedOrRethrow(raise: DefaultRaise): R =
 /** Serves as both purposes of a scope-reference token, and a default implementation for Raise. */
 @PublishedApi
 internal class DefaultRaise : Raise<Any?> {
-  override fun <B> raise(r: Any?): B = throw RaiseCancellationException(r, this)
+  override fun raise(r: Any?): Nothing = throw RaiseCancellationException(r, this)
 }
 
 /** CancellationException is required to cancel coroutines when raising from within them. */

diff --git a/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/continuations/Raise.kt b/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/continuations/Raise.kt
@@ -61,7 +61,7 @@ public annotation class EffectDSL
 public interface Raise<in R> {
 
   /** Raise a _logical failure_ of type [R] */
-  public fun <A> raise(r: R): A
+  public fun raise(r: R): Nothing
 
   /**
    * Invoke an [EagerEffect] inside `this` [Raise] context.

diff --git a/arrow-libs/core/arrow-core/src/commonTest/kotlin/arrow/core/continuations/EagerEffectSpec.kt b/arrow-libs/core/arrow-core/src/commonTest/kotlin/arrow/core/continuations/EagerEffectSpec.kt
@@ -36,7 +36,7 @@ class EagerEffectSpec : StringSpec({
       val promise = CompletableDeferred<Int>()
       eagerEffect {
         try {
-          raise<Int>(s)
+          raise(s)
         } finally {
           require(promise.complete(i))
         }
@@ -141,31 +141,34 @@ class EagerEffectSpec : StringSpec({
     }
   }
 
+  @Suppress("UNREACHABLE_CODE")
   "catch - error path and recover" {
     checkAll(Arb.int(), Arb.string()) { int, fallback ->
       eagerEffect<Int, String> {
-        raise<String>(int)
+        raise(int)
         fail("It should never reach this point")
       }.recover<Int, Nothing, String> { fallback }
         .runCont() shouldBe fallback
     }
   }
 
+  @Suppress("UNREACHABLE_CODE")
   "catch - error path and re-raise" {
     checkAll(Arb.int(), Arb.string()) { int, fallback ->
       eagerEffect<Int, Unit> {
-        raise<String>(int)
+        raise(int)
         fail("It should never reach this point")
       }.recover { raise(fallback) }
         .runCont() shouldBe fallback
     }
   }
 
+  @Suppress("UNREACHABLE_CODE")
   "catch - error path and throw" {
     checkAll(Arb.int(), Arb.string()) { int, msg ->
       shouldThrow<RuntimeException> {
         eagerEffect<Int, String> {
-          raise<String>(int)
+          raise(int)
           fail("It should never reach this point")
         }.recover<Int, Nothing, String> { throw RuntimeException(msg) }
           .runCont()

diff --git a/arrow-libs/core/arrow-core/src/commonTest/kotlin/arrow/core/continuations/EffectSpec.kt b/arrow-libs/core/arrow-core/src/commonTest/kotlin/arrow/core/continuations/EffectSpec.kt
@@ -47,7 +47,7 @@ class EffectSpec :
         val promise = CompletableDeferred<Int>()
         effect {
           try {
-            raise<Int>(s().suspend())
+            raise(s().suspend())
           } finally {
             require(promise.complete(i()))
           }
@@ -132,7 +132,7 @@ class EffectSpec :
     "short-circuit" {
       checkAll(Arb.string().suspend()) { msg ->
         effect {
-          raise<Int>(msg())
+          raise(msg())
         }.runCont() shouldBe msg()
       }
     }
@@ -299,31 +299,34 @@ class EffectSpec :
       }
     }
 
+    @Suppress("UNREACHABLE_CODE")
     "catch - error path and recover" {
       checkAll(Arb.int().suspend(), Arb.string().suspend()) { int, fallback ->
         effect<Int, String> {
-          raise<String>(int())
+          raise(int())
           fail("It should never reach this point")
         }.recover<Int, Nothing, String> { fallback() }
           .runCont() shouldBe fallback()
       }
     }
 
+    @Suppress("UNREACHABLE_CODE")
     "catch - error path and re-raise" {
       checkAll(Arb.int().suspend(), Arb.string().suspend()) { int, fallback ->
         effect<Int, Unit> {
-          raise<String>(int())
+          raise(int())
           fail("It should never reach this point")
         }.recover { raise(fallback()) }
           .runCont() shouldBe fallback()
       }
     }
 
+    @Suppress("UNREACHABLE_CODE")
     "catch - error path and throw" {
       checkAll(Arb.int().suspend(), Arb.string().suspend()) { int, msg ->
         shouldThrow<RuntimeException> {
           effect<Int, String> {
-            raise<String>(int())
+            raise(int())
             fail("It should never reach this point")
           }.recover<Int, Nothing, String> { throw RuntimeException(msg()) }
             .runCont()

diff --git a/arrow-libs/core/arrow-core/src/jvmTest/kotlin/examples/example-effect-05.kt b/arrow-libs/core/arrow-core/src/jvmTest/kotlin/examples/example-effect-05.kt
@@ -19,7 +19,7 @@ suspend fun <A> awaitExitCase(exit: CompletableDeferred<ExitCase>): A =
    val error = "Error"
    val exit = CompletableDeferred<ExitCase>()
   effect<String, Int> {
-    parZip({ awaitExitCase<Int>(exit) }, { raise<Int>(error) }) { a, b -> a + b }
+    parZip({ awaitExitCase<Int>(exit) }, { raise(error) }) { a: Int, b: Int -> a + b }
   }.fold({ it shouldBe error }, { fail("Int can never be the result") })
   exit.await().shouldBeTypeOf<ExitCase>()
 }
diff --git a/arrow-libs/core/arrow-core/src/jvmTest/kotlin/examples/example-effect-07.kt b/arrow-libs/core/arrow-core/src/jvmTest/kotlin/examples/example-effect-07.kt
@@ -23,7 +23,7 @@ suspend fun main() {
   val error = "Error"
   val exit = CompletableDeferred<ExitCase>()
   effect<String, Int> {
-    raceN({ awaitExitCase<Int>(exit) }) { raise<Int>(error) }
+    raceN({ awaitExitCase<Int>(exit) }) { raise(error) }
       .merge() // Flatten Either<Int, Int> result from race into Int
   }.fold({ msg -> msg shouldBe error }, { fail("Int can never be the result") })
   // It's possible not all parallel task got launched, and in those cases awaitCancellation never ran

diff --git a/arrow-libs/core/arrow-core/src/jvmTest/kotlin/examples/example-effect-09.kt b/arrow-libs/core/arrow-core/src/jvmTest/kotlin/examples/example-effect-09.kt
@@ -26,7 +26,7 @@ suspend fun main() {
   resourceScope {
     effect<String, Int> {
       val reader = bufferedReader("build.gradle.kts")
-      raise<Int>(error)
+      raise(error)
       reader.lineSequence().count()
     }.fold({ it shouldBe error }, { fail("Int can never be the result") })
   }