diff --git a/dataset/src/main/scala/frameless/ops/AggregateTypes.scala b/dataset/src/main/scala/frameless/ops/AggregateTypes.scala
index e46a0eff..403c2530 100644
--- a/dataset/src/main/scala/frameless/ops/AggregateTypes.scala
+++ b/dataset/src/main/scala/frameless/ops/AggregateTypes.scala
@@ -3,6 +3,15 @@ package ops
 
 import shapeless._
 
+/** A type class to extract the column types out of an HList of [[frameless.TypedAggregate]].
+  *
+  * @note This type class is mostly a workaround to issue with slow implicit derivation for Comapped.
+  * @example
+  * {{{
+  *   type U = TypedAggregate[T,A] :: TypedAggregate[T,B] :: TypedAggregate[T,C] :: HNil
+  *   type Out = A :: B :: C :: HNil
+  * }}}
+  */
 trait AggregateTypes[V, U <: HList] {
   type Out <: HList
 }
@@ -12,8 +21,8 @@ object AggregateTypes {
 
   implicit def deriveHNil[T]: AggregateTypes.Aux[T, HNil, HNil] = new AggregateTypes[T, HNil] { type Out = HNil }
 
-  implicit def deriveCons1[V, H, TT <: HList, T <: HList](
-    implicit tail: AggregateTypes.Aux[V, TT, T]
-  ): AggregateTypes.Aux[V, TypedAggregate[V, H] :: TT, H :: T] =
-    new AggregateTypes[V, TypedAggregate[V, H] :: TT] {type Out = H :: T}
+  implicit def deriveCons1[T, H, TT <: HList, V <: HList](
+    implicit tail: AggregateTypes.Aux[T, TT, V]
+  ): AggregateTypes.Aux[T, TypedAggregate[T, H] :: TT, H :: V] =
+    new AggregateTypes[T, TypedAggregate[T, H] :: TT] {type Out = H :: V}
 }
diff --git a/dataset/src/main/scala/frameless/ops/ColumnTypes.scala b/dataset/src/main/scala/frameless/ops/ColumnTypes.scala
index fb4d6c83..e5ae6aea 100644
--- a/dataset/src/main/scala/frameless/ops/ColumnTypes.scala
+++ b/dataset/src/main/scala/frameless/ops/ColumnTypes.scala
@@ -3,17 +3,26 @@ package ops
 
 import shapeless._
 
-trait ColumnTypes[V, U <: HList] {
+/** A type class to extract the column types out of an HList of [[frameless.TypedColumn]].
+  *
+  * @note This type class is mostly a workaround to issue with slow implicit derivation for Comapped.
+  * @example
+  * {{{
+  *   type U = TypedColumn[T,A] :: TypedColumn[T,B] :: TypedColumn[T,C] :: HNil
+  *   type Out = A :: B :: C :: HNil
+  * }}}
+  */
+trait ColumnTypes[T, U <: HList] {
   type Out <: HList
 }
 
 object ColumnTypes {
-  type Aux[V, U <: HList, Out0 <: HList] = ColumnTypes[V, U] {type Out = Out0}
+  type Aux[T, U <: HList, Out0 <: HList] = ColumnTypes[T, U] {type Out = Out0}
 
   implicit def deriveHNil[T]: ColumnTypes.Aux[T, HNil, HNil] = new ColumnTypes[T, HNil] { type Out = HNil }
 
-  implicit def deriveCons[V, H, TT <: HList, T <: HList](
-    implicit tail: ColumnTypes.Aux[V, TT, T]
-  ): ColumnTypes.Aux[V, TypedColumn[V, H] :: TT, H :: T] =
-    new ColumnTypes[V, TypedColumn[V, H] :: TT] {type Out = H :: T}
+  implicit def deriveCons[T, H, TT <: HList, V <: HList](
+    implicit tail: ColumnTypes.Aux[T, TT, V]
+  ): ColumnTypes.Aux[T, TypedColumn[T, H] :: TT, H :: V] =
+    new ColumnTypes[T, TypedColumn[T, H] :: TT] {type Out = H :: V}
 }
diff --git a/dataset/src/test/scala/frameless/ops/ColumnTypesTest.scala b/dataset/src/test/scala/frameless/ops/ColumnTypesTest.scala
new file mode 100644
index 00000000..303eb2cb
--- /dev/null
+++ b/dataset/src/test/scala/frameless/ops/ColumnTypesTest.scala
@@ -0,0 +1,27 @@
+package frameless
+package ops
+
+import org.scalacheck.Prop
+import org.scalacheck.Prop.forAll
+import shapeless.HNil
+import shapeless.::
+
+class ColumnTypesTest extends TypedDatasetSuite {
+  test("test summoning") {
+    def prop[A: TypedEncoder, B: TypedEncoder, C: TypedEncoder, D: TypedEncoder](data: Vector[X4[A, B, C, D]]): Prop = {
+      val d: TypedDataset[X4[A, B, C, D]] = TypedDataset.create(data)
+      val hlist = d('a) :: d('b) :: d('c) :: d('d) :: HNil
+
+      type TC[N] = TypedColumn[X4[A,B,C,D], N]
+
+      type IN = TC[A] :: TC[B] :: TC[C] :: TC[D] :: HNil
+      type OUT = A :: B :: C :: D :: HNil
+
+      implicitly[ColumnTypes.Aux[X4[A,B,C,D], IN, OUT]]
+      Prop.passed // successful compilation implies test correctness
+    }
+
+    check(forAll(prop[Int, String, X1[String], Boolean] _))
+    check(forAll(prop[Vector[Int], Vector[Vector[String]], X1[String], Option[String]] _))
+  }
+}