1 files changed, 32 insertions, 0 deletions
diff --git a/core/src/main/kotlin/ca/allanwang/kau/utils/Either.kt b/core/src/main/kotlin/ca/allanwang/kau/utils/Either.kt
new file mode 100644
index 0000000..dab5810
--- /dev/null
+++ b/core/src/main/kotlin/ca/allanwang/kau/utils/Either.kt
@@ -0,0 +1,32 @@
+package ca.allanwang.kau.utils
+
+/**
+ * Created by Allan Wang on 2017-06-17.
+ *
+ * Courtesy of adelnizamutdinov
+ *
+ * https://github.com/adelnizamutdinov/kotlin-either
+ */
+@Suppress("unused")
+sealed class Either<out L, out R>
+
+data class Left<out T>(val value: T) : Either<T, Nothing>()
+data class Right<out T>(val value: T) : Either<Nothing, T>()
+
+inline fun <L, R, T> Either<L, R>.fold(left: (L) -> T, right: (R) -> T): T =
+        when (this) {
+            is Left -> left(value)
+            is Right -> right(value)
+        }
+
+inline fun <L, R, T> Either<L, R>.flatMap(f: (R) -> Either<L, T>): Either<L, T> =
+        fold({ this as Left }, f)
+
+inline fun <L, R, T> Either<L, R>.map(f: (R) -> T): Either<L, T> =
+        flatMap { Right(f(it)) }
+
+val <T> Either<T, *>.isLeft: Boolean
+    get() = this is Left<T>
+
+val <T> Either<*, T>.isRight: Boolean
+    get() = this is Right<T>
+\ No newline at end of file