Merge pull request typelevel#1063 from typelevel/fix-IdT

fix IdT
kailuowang · May 26, 2016 · 8717aeb · 8717aeb
2 parents d14fc0a + 78ff38a
commit 8717aeb
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diff --git a/core/src/main/scala/cats/data/IdT.scala b/core/src/main/scala/cats/data/IdT.scala
@@ -25,7 +25,7 @@ final case class IdT[F[_], A](value: F[A]) {
     G.map(F.traverse(value)(f))(IdT(_))
 
   def ap[B](f: IdT[F, A => B])(implicit F: Apply[F]): IdT[F, B] =
-    IdT(F.ap(value)(f.value))
+    IdT(F.ap(f.value)(value))
 
 }
 

diff --git a/tests/src/test/scala/cats/tests/IdTTests.scala b/tests/src/test/scala/cats/tests/IdTTests.scala
@@ -2,11 +2,13 @@ package cats.tests
 
 import cats.{Foldable, Functor, Monad, Traverse}
 import cats.data.IdT
-import cats.laws.discipline.{FoldableTests, FunctorTests, MonadTests, SerializableTests, TraverseTests}
+import cats.laws.discipline.{CartesianTests, FoldableTests, FunctorTests, MonadTests, SerializableTests, TraverseTests}
 import cats.laws.discipline.arbitrary._
 
 class IdTTests extends CatsSuite {
 
+  implicit val iso = CartesianTests.Isomorphisms.invariant[IdT[List, ?]]
+
   checkAll("IdT[Functor, Int]", FunctorTests[IdT[List, ?]].functor[Int, Int, Int])
   checkAll("Functor[IdT[List, ?]]", SerializableTests.serializable(Functor[IdT[List, ?]]))