andThenRecover function added

michaelbull · Jan 23, 2024 · dfab2bd · dfab2bd
1 parent cb6edff
commit dfab2bd
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diff --git a/kotlin-result/src/commonMain/kotlin/com/github/michaelbull/result/And.kt b/kotlin-result/src/commonMain/kotlin/com/github/michaelbull/result/And.kt
@@ -42,6 +42,23 @@ public inline infix fun <V, E, U> Result<V, E>.andThen(transform: (V) -> Result<
     }
 }
 
+/**
+ * Returns the [transformation][transform] of the [error][Err.error] if this [Result] is [Err],
+ * otherwise this [Result].
+ */
+public inline fun <V, E> Result<V, E>.andThenRecover(
+    transform: (E) -> Result<V, E>
+): Result<V, E> {
+    contract {
+        callsInPlace(transform, InvocationKind.AT_MOST_ONCE)
+    }
+
+    return when (this) {
+        is Ok -> this
+        is Err -> transform(error)
+    }
+}
+
 /**
  * Returns the [transformation][transform] of the [error][Err.error] if this [Result] is [Err] and
  * satisfies the given [predicate], otherwise this [Result].

diff --git a/kotlin-result/src/commonTest/kotlin/com/github/michaelbull/result/AndTest.kt b/kotlin-result/src/commonTest/kotlin/com/github/michaelbull/result/AndTest.kt
@@ -43,6 +43,24 @@ class AndTest {
         }
     }
 
+    class AndThenRecover {
+        @Test
+        fun returnsValueIfOk() {
+            assertEquals(
+                expected = 5,
+                actual = Ok(5).andThenRecover { Ok(7) }.get()
+            )
+        }
+
+        @Test
+        fun returnsTransformValueIfErr() {
+            assertSame(
+                expected = 20,
+                actual = Err(AndError).andThenRecover { Ok(20) }.get()
+            )
+        }
+    }
+
     class AndThenRecoverIf {
         @Test
         fun returnsValueIfOk() {