Implement Either#merge() (#250)

arrow-kt · Nov 11, 2020 · b81b518 · b81b518
1 parent faad2fb
commit b81b518
Showing 1 changed file with 12 additions and 0 deletions.
diff --git a/arrow-core-data/src/main/kotlin/arrow/core/Either.kt b/arrow-core-data/src/main/kotlin/arrow/core/Either.kt
@@ -1183,6 +1183,18 @@ inline fun <A, B> EitherOf<A, B>.filterOrOther(predicate: (B) -> Boolean, defaul
     else Left(default(it))
   }
 
+/**
+ * Returns the value from this [Either.Right] or [Either.Left].
+ *
+ * Example:
+ * ```
+ * Right(12).merge() // Result: 12
+ * Left(12).merge() // Result: 12
+ * ```
+ */
+inline fun <A> EitherOf<A, A>.merge(): A =
+  fix().fold(::identity, ::identity)
+
 /**
  * Returns [Either.Right] with the existing value of [Either.Right] if this is an [Either.Right] with a non-null value.
  * The returned Either.Right type is not nullable.