toErrorIfNull to return Result with non-null value.

Resolves michaelbull#84
kirillzh · May 9, 2023 · 157e1ac · 157e1ac
1 parent ebe8f33
commit 157e1ac
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diff --git a/kotlin-result/src/commonMain/kotlin/com/github/michaelbull/result/Map.kt b/kotlin-result/src/commonMain/kotlin/com/github/michaelbull/result/Map.kt
@@ -195,15 +195,18 @@ public inline fun <V, E> Result<V, E>.toErrorIf(predicate: (V) -> Boolean, trans
  *
  * @see [toErrorIf]
  */
-public inline fun <V, E> Result<V, E>.toErrorIfNull(error: () -> E): Result<V, E> {
+public inline fun <V, E> Result<V?, E>.toErrorIfNull(error: () -> E): Result<V, E> {
     contract {
         callsInPlace(error, InvocationKind.AT_MOST_ONCE)
     }
 
     return toErrorIf(
         { it == null },
         { error() }
-    )
+    ).map {
+        @Suppress("UNCHECKED_CAST")
+        it as V
+    }
 }
 
 /**

diff --git a/kotlin-result/src/commonTest/kotlin/com/github/michaelbull/result/MapTest.kt b/kotlin-result/src/commonTest/kotlin/com/github/michaelbull/result/MapTest.kt
@@ -192,7 +192,7 @@ class MapTest {
 
         @Test
         fun returnsTransformedErrorIfNull() {
-            val result = Ok(null).toErrorIfNull { "a" }
+            val result: Result<Nothing, String> = Ok(null).toErrorIfNull { "a" }
 
             result as Err