Change return type of raise to Nothing

Implements arrow-kt#2805

arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/continuations/Builders.kt

@@ -38,7 +38,7 @@ 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 {
@@ -54,13 +54,13 @@ 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 }
 
@@ -76,7 +76,7 @@ public class IorRaise<E> @PublishedApi internal constructor(semigroup: Semigroup
   // TODO this is a mess...
   @PublishedApi
   internal var leftState: AtomicRef<Any?> = AtomicRef(EmptyValue)
-  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) {

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") })
  *   }

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 shifting from within them. */

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.

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))
         }
@@ -144,7 +144,7 @@ class EagerEffectSpec : StringSpec({
   "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
@@ -154,7 +154,7 @@ class EagerEffectSpec : StringSpec({
   "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
@@ -165,7 +165,7 @@ class EagerEffectSpec : StringSpec({
     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()

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()
       }
     }
@@ -302,7 +302,7 @@ class EffectSpec :
     "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()
@@ -312,7 +312,7 @@ class EffectSpec :
     "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()
@@ -323,7 +323,7 @@ class EffectSpec :
       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()

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>()
 }

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

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") })
   }