From 5ad3c4026422f3fd3aa24cded49d2e48423688ad Mon Sep 17 00:00:00 2001
From: Maxim Davydov <maximdavydoff@yandex.ru>
Date: Tue, 5 Nov 2019 18:23:22 +0300
Subject: [PATCH] #2947 Added bifold to Bifoldable typeclass (#3088)

* #2947 Added bifold to Bifoldable typeclass

* #2947 Formatted

* address Luka's feedback

* reformat
---
 core/src/main/scala/cats/Bifoldable.scala             | 5 +++++
 tests/src/test/scala/cats/tests/BifoldableSuite.scala | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/core/src/main/scala/cats/Bifoldable.scala b/core/src/main/scala/cats/Bifoldable.scala
index ae49e72d32..4098cbbf27 100644
--- a/core/src/main/scala/cats/Bifoldable.scala
+++ b/core/src/main/scala/cats/Bifoldable.scala
@@ -25,6 +25,11 @@ import simulacrum.typeclass
       val F = self
       val G = ev
     }
+
+  def bifold[A, B](fab: F[A, B])(implicit A: Monoid[A], B: Monoid[B]): (A, B) = {
+    import cats.instances.tuple._
+    bifoldMap(fab)((_, B.empty), (A.empty, _))
+  }
 }
 
 private[cats] trait ComposedBifoldable[F[_, _], G[_, _]] extends Bifoldable[λ[(α, β) => F[G[α, β], G[α, β]]]] {
diff --git a/tests/src/test/scala/cats/tests/BifoldableSuite.scala b/tests/src/test/scala/cats/tests/BifoldableSuite.scala
index 2dc2930c69..725035e70a 100644
--- a/tests/src/test/scala/cats/tests/BifoldableSuite.scala
+++ b/tests/src/test/scala/cats/tests/BifoldableSuite.scala
@@ -10,4 +10,9 @@ class BifoldableSuite extends CatsSuite {
 
   checkAll("Either compose Either", BifoldableTests(eitherComposeEither).bifoldable[Int, Int, Int])
   checkAll("Bifoldable[Either compose Either]", SerializableTests.serializable(eitherComposeEither))
+
+  test("bifold works for 2 monoids") {
+    Bifoldable[Either].bifold(Either.right[Int, String]("something")) should ===((0, "something"))
+    Bifoldable[Either].bifold(Either.left[Int, String](5)) should ===((5, ""))
+  }
 }