Binested sketch

core/src/main/scala/cats/data/Binested.scala

@@ -0,0 +1,25 @@
+package cats
+package data
+
+import cats.arrow.Profunctor
+
+final case class Binested[F[_, _], G[_], H[_], A, B](value: F[G[A], H[B]])
+
+object Binested {
+  implicit def catsDataEqForBinested[F[_, _], G[_], H[_], A, B](implicit F: Eq[F[G[A], H[B]]]): Eq[Binested[F, G, H, A, B]] =
+    Eq.by(_.value)
+
+  implicit def catsDataBifunctorForBinested[F[_, _], G[_], H[_]](
+    implicit F: Bifunctor[F], G: Functor[G], H: Functor[H]) =
+    new Bifunctor[λ[(ɑ, β) => Binested[F, G, H, ɑ, β]]] {
+      def bimap[A, B, C, D](fab: Binested[F, G, H, A, B])(f: A => C, g: B => D): Binested[F, G, H, C, D] =
+        Binested(F.bimap(fab.value)(G.map(_)(f), H.map(_)(g)))
+    }
+
+  implicit def catsDataProfunctorForBinested[F[_, _], G[_], H[_]](
+    implicit F: Profunctor[F], G: Functor[G], H: Functor[H]) =
+    new Profunctor[λ[(ɑ, β) => Binested[F, G, H, ɑ, β]]] {
+      def dimap[A, B, C, D](fab: Binested[F, G, H, A, B])(f: C => A)(g: B => D): Binested[F, G, H, C, D] =
+        Binested(F.dimap(fab.value)(G.map(_: G[C])(f))(H.map(_)(g)))
+    }
+}

laws/src/main/scala/cats/laws/discipline/Arbitrary.scala

@@ -228,6 +228,9 @@ object arbitrary extends ArbitraryInstances0 {
   implicit def catsLawsArbitraryForNested[F[_], G[_], A](implicit FG: Arbitrary[F[G[A]]]): Arbitrary[Nested[F, G, A]] =
     Arbitrary(FG.arbitrary.map(Nested(_)))
 
+  implicit def catsLawsArbitraryForBinested[F[_, _], G[_], H[_], A, B](implicit F: Arbitrary[F[G[A], H[B]]]): Arbitrary[Binested[F, G, H, A, B]] =
+    Arbitrary(F.arbitrary.map(Binested(_)))
+
   implicit def catsLawArbitraryForState[S: Arbitrary: Cogen, A: Arbitrary]: Arbitrary[State[S, A]] =
     catsLawArbitraryForIndexedStateT[Eval, S, S, A]
 

tests/src/test/scala/cats/tests/BinestedSuite.scala

@@ -0,0 +1,31 @@
+package cats
+package tests
+
+import cats.arrow.Profunctor
+import cats.data.Binested
+
+import cats.laws.discipline._
+import cats.laws.discipline.arbitrary._
+import cats.laws.discipline.eq._
+
+class BinestedSuite extends CatsSuite {
+  // we have a lot of generated lists of lists in these tests. We have to tell
+  // Scalacheck to calm down a bit so we don't hit memory and test duration
+  // issues.
+  implicit override val generatorDrivenConfig: PropertyCheckConfiguration =
+    PropertyCheckConfiguration(minSuccessful = 20, sizeRange = 5)
+
+  {
+    // Bifunctor + Functor + Functor = Bifunctor
+    implicit val instance = ListWrapper.functor
+    checkAll("Binested[Either, ListWrapper, Option, ?, ?]", BifunctorTests[Binested[Either, ListWrapper, Option, ?, ?]].bifunctor[Int, Int, Int, String, String, String])
+    checkAll("Bifunctor[Binested[Either, ListWrapper, Option, ?, ?]]", SerializableTests.serializable(Bifunctor[Binested[Either, ListWrapper, Option, ?, ?]]))
+  }
+
+  {
+    // Profunctor + Functor + Functor = Profunctor
+    implicit val instance = ListWrapper.functor
+    checkAll("Binested[Function1, ListWrapper, Option, ?, ?]", ProfunctorTests[Binested[Function1, ListWrapper, Option, ?, ?]].profunctor[Int, Int, Int, String, String, String])
+    checkAll("Profunctor[Binested[Function1, ListWrapper, Option, ?, ?]]", SerializableTests.serializable(Profunctor[Binested[Function1, ListWrapper, Option, ?, ?]]))
+  }
+}