From d7fd9375f29facdfa584cf4571b917dfaaf68c87 Mon Sep 17 00:00:00 2001
From: "junie-eap[bot]" <junie-eap[bot]@users.noreply.github.com>
Date: Fri, 6 Jun 2025 12:18:02 +0000
Subject: [PATCH] feat: implement getOrElseThrow in Either class  The
 `getOrElseThrow` method was successfully implemented in the Either class,
 which returns the right value or throws an exception for the left value. The
 implementation was validated by passing relevant tests, and the project
 guidelines were followed through proper build processes. All changes have now
 been submitted successfully.

---
 .../commonMain/kotlin/arrow/core/Either.kt    | 26 +++++++++++++++++++
 .../kotlin/arrow/core/EitherTest.kt           | 15 +++++++++++
 2 files changed, 41 insertions(+)

diff --git a/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/Either.kt b/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/Either.kt
index 7d6f69ad694..ac775b1586d 100644
--- a/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/Either.kt
+++ b/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/Either.kt
@@ -1344,6 +1344,32 @@ public inline infix fun <A, B> Either<A, B>.getOrElse(default: (A) -> B): B {
   }
 }
 
+/**
+ * Returns the right value [B] of this [Either],
+ * or throws an exception produced by applying the [onLeft] function to the left value [A].
+ *
+ * ```kotlin
+ * import arrow.core.Either
+ * import arrow.core.getOrElseThrow
+ * import io.kotest.assertions.throwables.shouldThrow
+ * import io.kotest.matchers.shouldBe
+ *
+ * fun test() {
+ *   Either.Right(12).getOrElseThrow { RuntimeException("Error: $it") } shouldBe 12
+ *   shouldThrow<RuntimeException> {
+ *     Either.Left("error").getOrElseThrow { RuntimeException("Error: $it") }
+ *   }.message shouldBe "Error: error"
+ * }
+ * ```
+ */
+public inline fun <A, B> Either<A, B>.getOrElseThrow(onLeft: (A) -> Throwable): B {
+  contract { callsInPlace(onLeft, InvocationKind.AT_MOST_ONCE) }
+  return when (this) {
+    is Left -> throw onLeft(this.value)
+    is Right -> this.value
+  }
+}
+
 /**
  * Returns the value from this [Right] or [Left].
  *
diff --git a/arrow-libs/core/arrow-core/src/commonTest/kotlin/arrow/core/EitherTest.kt b/arrow-libs/core/arrow-core/src/commonTest/kotlin/arrow/core/EitherTest.kt
index 8e570bcec97..fa6fae53ff1 100644
--- a/arrow-libs/core/arrow-core/src/commonTest/kotlin/arrow/core/EitherTest.kt
+++ b/arrow-libs/core/arrow-core/src/commonTest/kotlin/arrow/core/EitherTest.kt
@@ -129,6 +129,21 @@ class EitherTest {
       Left(a).getOrElse { b } shouldBe b
     }
   }
+  
+  @Test
+  fun getOrElseThrowOk() = runTest {
+    checkAll(Arb.int()) { a: Int ->
+      Right(a).getOrElseThrow { RuntimeException("Error: $it") } shouldBe a
+      
+      val left: Either<String, Int> = Left("error")
+      try {
+        left.getOrElseThrow { RuntimeException("Error: $it") }
+        fail("Should have thrown an exception")
+      } catch (e: RuntimeException) {
+        e.message shouldBe "Error: error"
+      }
+    }
+  }
 
   @Test
   fun getOrNullOk() = runTest {