From 4eb5d80f9115578c63ce8360c240caaea2897e0c Mon Sep 17 00:00:00 2001
From: Michael Bull <mikebull94@gmail.com>
Date: Thu, 1 Nov 2018 11:17:40 +0000
Subject: [PATCH] Add fold as an alias to mapBoth

---
 .../com/github/michaelbull/result/Map.kt      | 27 +++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/src/main/kotlin/com/github/michaelbull/result/Map.kt b/src/main/kotlin/com/github/michaelbull/result/Map.kt
index b03d9a2..7c2d579 100644
--- a/src/main/kotlin/com/github/michaelbull/result/Map.kt
+++ b/src/main/kotlin/com/github/michaelbull/result/Map.kt
@@ -56,20 +56,43 @@ inline infix fun <V, E, U> Result<Iterable<V>, E>.mapAll(transform: (V) -> Resul
  * - Elm: [Result.Extra.mapBoth](http://package.elm-lang.org/packages/elm-community/result-extra/2.2.0/Result-Extra#mapBoth)
  * - Haskell: [Data.Either.either](https://hackage.haskell.org/package/base-4.10.0.0/docs/Data-Either.html#v:either)
  */
-inline fun <V, E, U> Result<V, E>.mapBoth(success: (V) -> U, failure: (E) -> U): U {
+inline fun <V, E, U> Result<V, E>.mapBoth(
+    success: (V) -> U,
+    failure: (E) -> U
+): U {
     return when (this) {
         is Ok -> success(value)
         is Err -> failure(error)
     }
 }
 
+/**
+ * Maps this [Result<V, E>][Result] to `U` by applying either the [success] function if this
+ * [Result] is [Ok], or the [failure] function if this [Result] is an [Err]. Both of these
+ * functions must return the same type (`U`).
+ *
+ * This is functionally equivalent to [mapBoth].
+ *
+ * - Elm: [Result.Extra.mapBoth](http://package.elm-lang.org/packages/elm-community/result-extra/2.2.0/Result-Extra#mapBoth)
+ * - Haskell: [Data.Either.either](https://hackage.haskell.org/package/base-4.10.0.0/docs/Data-Either.html#v:either)
+ */
+inline fun <V, E, U> Result<V, E>.fold(
+    success: (V) -> U,
+    failure: (E) -> U
+): U {
+    return mapBoth(success, failure)
+}
+
 /**
  * Maps this [Result<V, E>][Result] to [Result<U, F>][Result] by applying either the [success]
  * function if this [Result] is [Ok], or the [failure] function if this [Result] is an [Err].
  *
  * - Haskell: [Data.Bifunctor.Bimap](https://hackage.haskell.org/package/base-4.10.0.0/docs/Data-Bifunctor.html#v:bimap)
  */
-inline fun <V, E, U, F> Result<V, E>.mapEither(success: (V) -> U, failure: (E) -> F): Result<U, F> {
+inline fun <V, E, U, F> Result<V, E>.mapEither(
+    success: (V) -> U,
+    failure: (E) -> F
+): Result<U, F> {
     return when (this) {
         is Ok -> Ok(success(value))
         is Err -> Err(failure(error))