From e60f956622ec16948c907e1616145cebd4216a2f Mon Sep 17 00:00:00 2001
From: hoangchung <52132635+hoangchungk53qx1@users.noreply.github.com>
Date: Wed, 31 Jul 2024 01:48:44 +0700
Subject: [PATCH 1/3] Update link monad_comprehensions Arrow (Kotlin) README.md

Update the error link Arrow kotlin
---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 9cf85a8..04b8e7a 100644
--- a/README.md
+++ b/README.md
@@ -177,7 +177,7 @@ The `binding` function primarily draws inspiration from
 [Bow's `binding` function][bow-bindings], however below is a list of other
 resources on the topic of monad comprehensions.
 
-- [Monad comprehensions - Arrow (Kotlin)](https://arrow-kt.io/docs/0.10/patterns/monad_comprehensions/)
+- [Monad comprehensions - Arrow (Kotlin)](https://old.arrow-kt.io/docs/patterns/monad_comprehensions/)
 - [Monad comprehensions - Bow (Swift)](https://bow-swift.io/docs/patterns/monad-comprehensions)
 - [For comprehensions - Scala](https://docs.scala-lang.org/tour/for-comprehensions.html)
 

From e0ef5f78dce7bd7e55162e144b2ecb18be542251 Mon Sep 17 00:00:00 2001
From: hoangchungk53qx1 <hoangchungk53qx1@gmail.com>
Date: Mon, 7 Apr 2025 03:00:56 +0700
Subject: [PATCH 2/3] Add traverse function to Iterable and corresponding tests

---
 .../com/github/michaelbull/result/Iterable.kt | 19 +++++++++++
 .../github/michaelbull/result/IterableTest.kt | 32 +++++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/kotlin-result/src/commonMain/kotlin/com/github/michaelbull/result/Iterable.kt b/kotlin-result/src/commonMain/kotlin/com/github/michaelbull/result/Iterable.kt
index c1c86a0..bae3130 100644
--- a/kotlin-result/src/commonMain/kotlin/com/github/michaelbull/result/Iterable.kt
+++ b/kotlin-result/src/commonMain/kotlin/com/github/michaelbull/result/Iterable.kt
@@ -385,3 +385,22 @@ public inline fun <V, E, U : Any, C : MutableCollection<in U>> Iterable<V>.mapRe
 
     return Ok(values)
 }
+
+/**
+ * Applies the given [transform] function to each element in this [Iterable<V>], collecting the results into a [Result<List<U>, E>].
+ * If all transformations succeed, returns an [Ok] containing a list of [U] values in the same order as the original [Iterable].
+ * If any transformation fails, immediately returns the first [Err]
+ * encountered and stops processing further elements.
+ */
+public fun <V, E, U> Iterable<V>.traverse(transform: (V) -> Result<U, E>): Result<List<U>, E> {
+    val results = mutableListOf<U>()
+    for (item in this) {
+        val result = transform(item)
+        val element  = when {
+            result.isOk -> result.value
+            else -> return Err(result.error)
+        }
+        results.add(element)
+    }
+    return Ok(results)
+}
diff --git a/kotlin-result/src/commonTest/kotlin/com/github/michaelbull/result/IterableTest.kt b/kotlin-result/src/commonTest/kotlin/com/github/michaelbull/result/IterableTest.kt
index 3442ee0..988684b 100644
--- a/kotlin-result/src/commonTest/kotlin/com/github/michaelbull/result/IterableTest.kt
+++ b/kotlin-result/src/commonTest/kotlin/com/github/michaelbull/result/IterableTest.kt
@@ -199,4 +199,36 @@ class IterableTest {
             )
         }
     }
+
+    class Traverse {
+        @Test
+        fun returnTraverseValueIfOk() {
+            val input = listOf(1, 2, 3)
+            val transform: (Int) -> Result<String, String> = { Ok(it.toString()) }
+            val result = input.traverse(transform)
+
+            assertEquals(Ok(listOf("1", "2", "3")), result)
+        }
+
+        @Test
+        fun returnsFirstErrorIfErr() {
+            val input = listOf(1, 2, 3)
+            val transform: (Int) -> Result<String, String> = {
+                if (it == 1) Err("Error at 1") else Ok(it.toString())
+            }
+            val result = input.traverse(transform)
+
+            assertEquals(Err("Error at 1"), result)
+        }
+
+        @Test
+        fun traverseWithEmptyListReturnsEmptyOkList() {
+            val input = emptyList<Int>()
+            val transform: (Int) -> Result<String, String> = { Ok(it.toString()) }
+            val result = input.traverse(transform)
+
+            assertEquals(Ok(emptyList()), result)
+        }
+
+    }
 }

From 4fc24880059b10e5f6bd70acb9a4e082f46ad7cd Mon Sep 17 00:00:00 2001
From: hoangchungk53qx1 <hoangchungk53qx1@gmail.com>
Date: Mon, 7 Apr 2025 22:59:51 +0700
Subject: [PATCH 3/3] Refactor traverse function in Iterable to use fold for
 improved

---
 .../com/github/michaelbull/result/Iterable.kt  | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/kotlin-result/src/commonMain/kotlin/com/github/michaelbull/result/Iterable.kt b/kotlin-result/src/commonMain/kotlin/com/github/michaelbull/result/Iterable.kt
index bae3130..3fc9d74 100644
--- a/kotlin-result/src/commonMain/kotlin/com/github/michaelbull/result/Iterable.kt
+++ b/kotlin-result/src/commonMain/kotlin/com/github/michaelbull/result/Iterable.kt
@@ -392,15 +392,13 @@ public inline fun <V, E, U : Any, C : MutableCollection<in U>> Iterable<V>.mapRe
  * If any transformation fails, immediately returns the first [Err]
  * encountered and stops processing further elements.
  */
-public fun <V, E, U> Iterable<V>.traverse(transform: (V) -> Result<U, E>): Result<List<U>, E> {
-    val results = mutableListOf<U>()
-    for (item in this) {
-        val result = transform(item)
-        val element  = when {
-            result.isOk -> result.value
-            else -> return Err(result.error)
+public inline fun <V, E, U> Iterable<V>.traverse(transform: (V) -> Result<U, E>): Result<List<U>, E> {
+    return fold(
+        initial = emptyList<U>(),
+        operation = { acc: List<U>, element: V ->
+            transform(element).map { value ->
+                acc + value
+            }
         }
-        results.add(element)
-    }
-    return Ok(results)
+    )
 }