add Functor[TheseT]

(cherry picked from commit d3efbe9)
scalaz · Apr 5, 2017 · 5bf9082 · 5bf9082
1 parent 1eb7dc1
commit 5bf9082
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Showing 2 changed files with 23 additions and 3 deletions.
diff --git a/core/src/main/scala/scalaz/TheseT.scala b/core/src/main/scala/scalaz/TheseT.scala
@@ -91,7 +91,8 @@ final case class TheseT[F[_], A, B](run: F[A \&/ B]) {
 
 sealed abstract class TheseTInstances1 {
   implicit def TheseTInstance1[F[_]: Traverse, L]: Traverse[TheseT[F, L, ?]]
-  = new Traverse[TheseT[F, L, ?]] {
+  = new Traverse[TheseT[F, L, ?]] with TheseTFunctor[F, L] {
+    override def F = implicitly
     override def traverseImpl[G[_], A, B](fa: TheseT[F, L, A])(f: (A) => G[B])(implicit A: Applicative[G]) =
       fa.traverse(f)
 
@@ -111,7 +112,8 @@ sealed abstract class TheseTInstances1 {
 
 sealed abstract class TheseTInstances0 extends TheseTInstances1 {
   implicit def theseTMonad[F[_]: Monad, L: Semigroup]: Monad[TheseT[F, L, ?]]
-  = new Monad[TheseT[F, L, ?]] {
+  = new Monad[TheseT[F, L, ?]] with TheseTFunctor[F, L] {
+    override def F = implicitly
 
     override def bind[A, B](fa: TheseT[F, L, A])(f: (A) => TheseT[F, L, B]) = fa.flatMap(f)
 
@@ -132,7 +134,12 @@ sealed abstract class TheseTInstances0 extends TheseTInstances1 {
     F0.contramap((_: TheseT[F, A, B]).run)
 
 }
-sealed abstract class TheseTInstances extends TheseTInstances0
+sealed abstract class TheseTInstances extends TheseTInstances0 {
+  implicit def theseTFunctor[F[_]: Functor, L]: Functor[TheseT[F, L, ?]] =
+    new TheseTFunctor[F, L] {
+      override def F = implicitly
+    }
+}
 
 object TheseT extends TheseTInstances {
   def theseT[F[_], A, B](a: F[A \&/ B]): TheseT[F, A, B] = TheseT(a)
@@ -143,3 +150,9 @@ object TheseT extends TheseTInstances {
 
 }
 
+private trait TheseTFunctor[F[_], L] extends Functor[TheseT[F, L, ?]] {
+  protected implicit def F: Functor[F]
+
+  override final def map[A, B](fa: TheseT[F, L, A])(f: A => B) =
+    fa map f
+}
diff --git a/tests/src/test/scala/scalaz/TheseTTest.scala b/tests/src/test/scala/scalaz/TheseTTest.scala
@@ -14,4 +14,11 @@ object TheseTTest extends SpecLite {
   checkAll(traverse.laws[TheseTListInt])
   checkAll(bitraverse.laws[TheseTList])
 
+  object instances {
+    def functor[F[_]: Functor, L] = Functor[TheseT[F, L, ?]]
+
+    // checking absence of ambiguity
+    def functor[F[_]: Traverse, L] = Functor[TheseT[F, L, ?]]
+    def functor[F[_]: Monad, L: Semigroup] = Functor[TheseT[F, L, ?]]
+  }
 }