Add merge builder for raise (#3061)

Co-authored-by: Simon Vergauwen <nomisRev@users.noreply.github.com> Co-authored-by: Francisco Diaz <francisco.d@47deg.com>
arrow-kt · Jun 19, 2023 · 3d7cb6e · 3d7cb6e
1 parent f8c50f3
commit 3d7cb6e
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Showing 6 changed files with 44 additions and 8 deletions.
diff --git a/arrow-libs/core/arrow-core/api/arrow-core.api b/arrow-libs/core/arrow-core/api/arrow-core.api
@@ -3421,6 +3421,7 @@ public abstract interface annotation class arrow/core/raise/RaiseDSL : java/lang
 public final class arrow/core/raise/RaiseKt {
 	public static final fun _fold (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public static final fun _foldOrThrow (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
+	public static final fun _merge (Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public static final fun catch (Lkotlin/jvm/functions/Function0;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public static final fun catch (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function2;)Lkotlin/jvm/functions/Function1;
 	public static final fun catch (Lkotlin/jvm/functions/Function2;)Lkotlin/jvm/functions/Function2;

diff --git a/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/raise/Builders.kt b/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/raise/Builders.kt
@@ -26,7 +26,7 @@ public inline fun <Error, A> either(@BuilderInference block: Raise<Error>.() ->
   fold({ block.invoke(this) }, { Either.Left(it) }, { Either.Right(it) })
 
 public inline fun <A> nullable(block: NullableRaise.() -> A): A? =
-  fold({ block(NullableRaise(this)) }, { null }, ::identity)
+  merge { block(NullableRaise(this)) }
 
 public inline fun <A> result(block: ResultRaise.() -> A): Result<A> =
   fold({ block(ResultRaise(this)) }, Result.Companion::failure, Result.Companion::failure, Result.Companion::success)

diff --git a/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/raise/Effect.kt b/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/raise/Effect.kt
@@ -3,7 +3,6 @@
 @file:OptIn(ExperimentalTypeInference::class)
 package arrow.core.raise
 
-import arrow.core.identity
 import kotlin.experimental.ExperimentalTypeInference
 import kotlin.jvm.JvmMultifileClass
 import kotlin.jvm.JvmName
@@ -672,11 +671,9 @@ public typealias EagerEffect<Error, A> = Raise<Error>.() -> A
 
 public inline fun <Error, A> eagerEffect(@BuilderInference noinline block: Raise<Error>.() -> A): EagerEffect<Error, A> = block
 
-public suspend fun <A> Effect<A, A>.merge(): A = getOrElse(::identity)
-public fun <A> EagerEffect<A, A>.merge(): A = getOrElse(::identity)
+public suspend fun <A> Effect<A, A>.merge(): A = merge { invoke() }
+public fun <A> EagerEffect<A, A>.merge(): A = merge { invoke() }
 
-@Suppress("IMPLICIT_NOTHING_TYPE_ARGUMENT_IN_RETURN_POSITION")
-public suspend fun <A> Effect<Nothing, A>.get(): A = getOrElse(::identity)
+public suspend fun <A> Effect<Nothing, A>.get(): A = merge()
 
-@Suppress("IMPLICIT_NOTHING_TYPE_ARGUMENT_IN_RETURN_POSITION")
-public fun <A> EagerEffect<Nothing, A>.get(): A = getOrElse(::identity)
+public fun <A> EagerEffect<Nothing, A>.get(): A = merge()
diff --git a/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/raise/Raise.kt b/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/raise/Raise.kt
@@ -486,3 +486,27 @@ public inline fun <Error, OtherError, A> Raise<Error>.withError(
   }
   return recover(block) { raise(transform(it)) }
 }
+
+/**
+ * Execute the [Raise] context function resulting in [A] or any _logical error_ of type [A].
+ * Does not distinguish between normal results and errors, thus you can consider
+ * `return` and `raise` to be semantically equivalent inside.
+ *
+ * <!--- INCLUDE
+ * import arrow.core.raise.merge
+ * import io.kotest.matchers.shouldBe
+ * import kotlin.random.Random
+ * -->
+ * ```kotlin
+ * fun test() {
+ *   merge { if(Random.nextBoolean()) raise("failed") else "failed" } shouldBe "failed"
+ * }
+ * ```
+ * <!--- KNIT example-raise-dsl-12.kt -->
+ * <!--- TEST lines.isEmpty() -->
+ */
+@RaiseDSL
+@JvmName("_merge")
+public inline fun <A> merge(
+  @BuilderInference block: Raise<A>.() -> A,
+): A = recover(block, ::identity)
diff --git a/arrow-libs/core/arrow-core/src/jvmTest/kotlin/examples/example-raise-dsl-12.kt b/arrow-libs/core/arrow-core/src/jvmTest/kotlin/examples/example-raise-dsl-12.kt
@@ -0,0 +1,10 @@
+// This file was automatically generated from Raise.kt by Knit tool. Do not edit.
+package arrow.core.examples.exampleRaiseDsl12
+
+import arrow.core.raise.merge
+import io.kotest.matchers.shouldBe
+import kotlin.random.Random
+
+fun test() {
+  merge { if(Random.nextBoolean()) raise("failed") else "failed" } shouldBe "failed"
+}
diff --git a/arrow-libs/core/arrow-core/src/jvmTest/kotlin/examples/test/RaiseKnitTest.kt b/arrow-libs/core/arrow-core/src/jvmTest/kotlin/examples/test/RaiseKnitTest.kt
@@ -44,6 +44,10 @@ class RaiseKnitTest : StringSpec({
     arrow.core.examples.exampleRaiseDsl11.test()
   }
 
+  "ExampleRaiseDsl12" {
+    arrow.core.examples.exampleRaiseDsl12.test()
+  }
+
 }) {
   override fun timeout(): Long = 1000
 }