Merge pull request #696 from ceedubs/writert-instances

Add more WriterT instances
typelevel · Nov 25, 2015 · 4fbe9dd · 4fbe9dd
2 parents efe4af7 + 355db32
commit 4fbe9dd
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Showing 3 changed files with 139 additions and 10 deletions.
diff --git a/core/src/main/scala/cats/data/WriterT.scala b/core/src/main/scala/cats/data/WriterT.scala
@@ -65,9 +65,9 @@ private[data] sealed abstract class WriterTInstances extends WriterTInstances0 {
 }
 
 private[data] sealed abstract class WriterTInstances0 extends WriterTInstances1 {
-  implicit def writerTMonad[F[_], L](implicit F: Monad[F], L: Monoid[L]): Monad[WriterT[F, L, ?]] =
-    new WriterTMonad[F, L] {
-      implicit val F0: Monad[F] = F
+  implicit def writerTMonadCombine[F[_], L](implicit F: MonadCombine[F], L: Monoid[L]): MonadCombine[WriterT[F, L, ?]] =
+    new WriterTMonadCombine[F, L] {
+      implicit val F0: MonadCombine[F] = F
       implicit val L0: Monoid[L] = L
     }
 
@@ -82,29 +82,63 @@ private[data] sealed abstract class WriterTInstances0 extends WriterTInstances1
 }
 
 private[data] sealed abstract class WriterTInstances1 extends WriterTInstances2 {
+  implicit def writerTMonadFilter[F[_], L](implicit F: MonadFilter[F], L: Monoid[L]): MonadFilter[WriterT[F, L, ?]] =
+    new WriterTMonadFilter[F, L] {
+      implicit val F0: MonadFilter[F] = F
+      implicit val L0: Monoid[L] = L
+    }
+}
+private[data] sealed abstract class WriterTInstances2 extends WriterTInstances3 {
+  implicit def writerTMonad[F[_], L](implicit F: Monad[F], L: Monoid[L]): Monad[WriterT[F, L, ?]] =
+    new WriterTMonad[F, L] {
+      implicit val F0: Monad[F] = F
+      implicit val L0: Monoid[L] = L
+    }
+}
+
+private[data] sealed abstract class WriterTInstances3 extends WriterTInstances4 {
+  implicit def writerTAlternative[F[_], L](implicit F: Alternative[F], L: Monoid[L]): Alternative[WriterT[F, L, ?]] =
+    new WriterTAlternative[F, L] {
+      implicit val F0: Alternative[F] = F
+      implicit val L0: Monoid[L] = L
+    }
+}
+
+private[data] sealed abstract class WriterTInstances4 extends WriterTInstances5 {
   implicit def writerTApplicative[F[_], L](implicit F: Applicative[F], L: Monoid[L]): Applicative[WriterT[F, L, ?]] =
     new WriterTApplicative[F, L] {
       implicit val F0: Applicative[F] = F
       implicit val L0: Monoid[L] = L
     }
+
+  implicit def writerTMonoidK[F[_], L](implicit F: MonoidK[F]): MonoidK[WriterT[F, L, ?]] =
+    new WriterTMonoidK[F, L] {
+      implicit val F0: MonoidK[F] = F
+    }
 }
-private[data] sealed abstract class WriterTInstances2 extends WriterTInstances3 {
+
+private[data] sealed abstract class WriterTInstances5 extends WriterTInstances6 {
   implicit def writerTFlatMap[F[_], L](implicit F: FlatMap[F], L: Semigroup[L]): FlatMap[WriterT[F, L, ?]] =
     new WriterTFlatMap[F, L] {
       implicit val F0: FlatMap[F] = F
       implicit val L0: Semigroup[L] = L
     }
+
+  implicit def writerTSemigroupK[F[_], L](implicit F: SemigroupK[F]): SemigroupK[WriterT[F, L, ?]] =
+    new WriterTSemigroupK[F, L] {
+      implicit val F0: SemigroupK[F] = F
+    }
 }
 
-private[data] sealed abstract class WriterTInstances3 extends WriterTInstances4 {
+private[data] sealed abstract class WriterTInstances6 extends WriterTInstances7 {
   implicit def writerTApply[F[_], L](implicit F: Apply[F], L: Semigroup[L]): Apply[WriterT[F, L, ?]] =
     new WriterTApply[F, L] {
       implicit val F0: Apply[F] = F
       implicit val L0: Semigroup[L] = L
     }
 }
 
-private[data] sealed abstract class WriterTInstances4 {
+private[data] sealed abstract class WriterTInstances7 {
   implicit def writerTFunctor[F[_], L](implicit F: Functor[F]): Functor[WriterT[F, L, ?]] = new WriterTFunctor[F, L] {
     implicit val F0: Functor[F] = F
   }
@@ -149,6 +183,33 @@ private[data] sealed trait WriterTMonad[F[_], L] extends WriterTApplicative[F, L
     fa.flatMap(f)
 }
 
+private[data] sealed trait WriterTSemigroupK[F[_], L] extends SemigroupK[WriterT[F, L, ?]] {
+  implicit def F0: SemigroupK[F]
+
+  def combine[A](x: WriterT[F, L, A], y: WriterT[F, L, A]): WriterT[F, L, A] =
+    WriterT(F0.combine(x.run, y.run))
+}
+
+private[data] sealed trait WriterTMonoidK[F[_], L] extends MonoidK[WriterT[F, L, ?]] with WriterTSemigroupK[F, L] {
+  override implicit def F0: MonoidK[F]
+
+  def empty[A]: WriterT[F, L, A] = WriterT(F0.empty)
+}
+
+private[data] sealed trait WriterTAlternative[F[_], L] extends Alternative[WriterT[F, L, ?]] with WriterTMonoidK[F, L] with WriterTApplicative[F, L] {
+  override implicit def F0: Alternative[F]
+}
+
+private[data] sealed trait WriterTMonadFilter[F[_], L] extends MonadFilter[WriterT[F, L, ?]] with WriterTMonad[F, L] {
+  override implicit def F0: MonadFilter[F]
+
+  def empty[A]: WriterT[F, L, A] = WriterT(F0.empty)
+}
+
+private[data] sealed trait WriterTMonadCombine[F[_], L] extends MonadCombine[WriterT[F, L, ?]] with WriterTMonad[F, L] with WriterTAlternative[F, L] {
+  override implicit def F0: MonadCombine[F]
+}
+
 trait WriterTFunctions {
   def putT[F[_], L, V](vf: F[V])(l: L)(implicit functorF: Functor[F]): WriterT[F, L, V] =
     WriterT(functorF.map(vf)(v => (l, v)))

diff --git a/tests/src/test/scala/cats/tests/ListWrapper.scala b/tests/src/test/scala/cats/tests/ListWrapper.scala
@@ -84,6 +84,12 @@ object ListWrapper {
     }
   }
 
+  def monoidK: MonoidK[ListWrapper] = monadCombine
+
+  def monadFilter: MonadFilter[ListWrapper] = monadCombine
+
+  def alternative: Alternative[ListWrapper] = monadCombine
+
   def monoid[A]: Monoid[ListWrapper[A]] = monadCombine.algebra[A]
 
   implicit def listWrapperArbitrary[A: Arbitrary]: Arbitrary[ListWrapper[A]] =

diff --git a/tests/src/test/scala/cats/tests/WriterTTests.scala b/tests/src/test/scala/cats/tests/WriterTTests.scala
@@ -44,6 +44,24 @@ class WriterTTests extends CatsSuite {
     }
   }
 
+  {
+    // F has a SemigroupK
+    implicit val F: SemigroupK[ListWrapper] = ListWrapper.semigroupK
+
+    checkAll("WriterT[ListWrapper, ListWrapper[Int], ?]", SemigroupKTests[WriterT[ListWrapper, ListWrapper[Int], ?]].semigroupK[Int])
+    checkAll("SemigroupK[WriterT[ListWrapper, ListWrapper[Int], ?]]", SerializableTests.serializable(SemigroupK[WriterT[ListWrapper, ListWrapper[Int], ?]]))
+  }
+
+  {
+    // F has a MonoidK
+    implicit val F: MonoidK[ListWrapper] = ListWrapper.monoidK
+
+    SemigroupK[WriterT[ListWrapper, ListWrapper[Int], ?]]
+
+    checkAll("WriterT[ListWrapper, ListWrapper[Int], ?]", MonoidKTests[WriterT[ListWrapper, ListWrapper[Int], ?]].monoidK[Int])
+    checkAll("MonoidK[WriterT[ListWrapper, ListWrapper[Int], ?]]", SerializableTests.serializable(MonoidK[WriterT[ListWrapper, ListWrapper[Int], ?]]))
+  }
+
   {
     // F has a Functor and L has no Semigroup
     implicit val F: Functor[ListWrapper] = ListWrapper.functor
@@ -69,7 +87,7 @@ class WriterTTests extends CatsSuite {
   {
     // F has an Apply and L has a Semigroup
     implicit val F: Apply[ListWrapper] = ListWrapper.monadCombine
-    implicit val L: Semigroup[ListWrapper[Int]] = ListWrapper.semigroupK.algebra[Int]
+    implicit val L: Semigroup[ListWrapper[Int]] = ListWrapper.semigroup[Int]
 
     Functor[WriterT[ListWrapper, ListWrapper[Int], ?]]
     checkAll("WriterT[ListWrapper, ListWrapper[Int], ?]", ApplyTests[WriterT[ListWrapper, ListWrapper[Int], ?]].apply[Int, Int, Int])
@@ -88,7 +106,7 @@ class WriterTTests extends CatsSuite {
   {
     // F has a FlatMap and L has a Semigroup
     implicit val F: FlatMap[ListWrapper] = ListWrapper.monadCombine
-    implicit val L: Semigroup[ListWrapper[Int]] = ListWrapper.semigroupK.algebra[Int]
+    implicit val L: Semigroup[ListWrapper[Int]] = ListWrapper.semigroup[Int]
 
     Functor[WriterT[ListWrapper, ListWrapper[Int], ?]]
     Apply[WriterT[ListWrapper, ListWrapper[Int], ?]]
@@ -111,7 +129,7 @@ class WriterTTests extends CatsSuite {
   {
     // F has an Applicative and L has a Monoid
     implicit val F: Applicative[ListWrapper] = ListWrapper.monadCombine
-    implicit val L: Monoid[ListWrapper[Int]] = ListWrapper.monadCombine.algebra[Int]
+    implicit val L: Monoid[ListWrapper[Int]] = ListWrapper.monoid[Int]
 
     Functor[WriterT[ListWrapper, ListWrapper[Int], ?]]
     Apply[WriterT[ListWrapper, ListWrapper[Int], ?]]
@@ -134,7 +152,7 @@ class WriterTTests extends CatsSuite {
   {
     // F has a Monad and L has a Monoid
     implicit val F: Monad[ListWrapper] = ListWrapper.monadCombine
-    implicit val L: Monoid[ListWrapper[Int]] = ListWrapper.monadCombine.algebra[Int]
+    implicit val L: Monoid[ListWrapper[Int]] = ListWrapper.monoid[Int]
 
     Functor[WriterT[ListWrapper, ListWrapper[Int], ?]]
     Apply[WriterT[ListWrapper, ListWrapper[Int], ?]]
@@ -161,4 +179,48 @@ class WriterTTests extends CatsSuite {
     FlatMap[Logged]
     Monad[Logged]
   }
+
+  {
+    // F has an Alternative and L has a Monoid
+    implicit val F: Alternative[ListWrapper] = ListWrapper.alternative
+    implicit val L: Monoid[ListWrapper[Int]] = ListWrapper.monoid[Int]
+
+    Functor[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    Apply[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    Applicative[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    checkAll("WriterT[ListWrapper, ListWrapper[Int], ?]", AlternativeTests[WriterT[ListWrapper, ListWrapper[Int], ?]].alternative[Int, Int, Int])
+    checkAll("Alternative[WriterT[ListWrapper, ListWrapper[Int], ?]]", SerializableTests.serializable(Alternative[WriterT[ListWrapper, ListWrapper[Int], ?]]))
+  }
+
+  {
+    // F has a MonadFilter and L has a Monoid
+    implicit val F: MonadFilter[ListWrapper] = ListWrapper.monadFilter
+    implicit val L: Monoid[ListWrapper[Int]] = ListWrapper.monoid[Int]
+
+    Functor[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    Apply[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    Applicative[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    FlatMap[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    Monad[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    checkAll("WriterT[ListWrapper, ListWrapper[Int], ?]", MonadFilterTests[WriterT[ListWrapper, ListWrapper[Int], ?]].monadFilter[Int, Int, Int])
+    checkAll("MonadFilter[WriterT[ListWrapper, ListWrapper[Int], ?]]", SerializableTests.serializable(MonadFilter[WriterT[ListWrapper, ListWrapper[Int], ?]]))
+  }
+
+  {
+    // F has a MonadCombine and L has a Monoid
+    implicit val F: MonadCombine[ListWrapper] = ListWrapper.monadCombine
+    implicit val L: Monoid[ListWrapper[Int]] = ListWrapper.monoid[Int]
+
+    Functor[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    Apply[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    Applicative[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    FlatMap[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    Monad[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    MonadFilter[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    Alternative[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    SemigroupK[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    MonoidK[WriterT[ListWrapper, ListWrapper[Int], ?]]
+    checkAll("WriterT[ListWrapper, ListWrapper[Int], ?]", MonadCombineTests[WriterT[ListWrapper, ListWrapper[Int], ?]].monadCombine[Int, Int, Int])
+    checkAll("MonadCombine[WriterT[ListWrapper, ListWrapper[Int], ?]]", SerializableTests.serializable(MonadCombine[WriterT[ListWrapper, ListWrapper[Int], ?]]))
+  }
 }