diff --git a/modules/core/src/main/scala/SchemaModule.scala b/modules/core/src/main/scala/SchemaModule.scala
index 896b335..d80aec2 100644
--- a/modules/core/src/main/scala/SchemaModule.scala
+++ b/modules/core/src/main/scala/SchemaModule.scala
@@ -161,23 +161,23 @@ trait Interpreter[Prim[_], SumTermId, ProductTermId, F[_]] {
    * A natural transformation that will transform a schema for any type `A`
    * into an `F[A]`.
    */
-  def interpret: Schema.FSchema[Prim, SumTermId, ProductTermId, ?] ~> F
+  def interpret: SchemaF.FSchema[Prim, SumTermId, ProductTermId, ?] ~> F
 }
 
 object SchemaF {
 
   implicit def schemaHFunctor[Prim[_], SumTermId, ProductTermId] =
-    new HFunctor[Schema[Prim, SumTermId, ProductTermId, ?[_], ?]] {
+    new HFunctor[SchemaF[Prim, SumTermId, ProductTermId, ?[_], ?]] {
 
       def hmap[F[_], G[_]](nt: F ~> G) =
-        new (Schema[Prim, SumTermId, ProductTermId, F, ?] ~> Schema[
+        new (SchemaF[Prim, SumTermId, ProductTermId, F, ?] ~> SchemaF[
           Prim,
           SumTermId,
           ProductTermId,
           G,
           ?
         ]) {
-          def apply[A](fa: Schema[Prim, SumTermId, ProductTermId, F, A]) = fa.hmap(nt)
+          def apply[A](fa: SchemaF[Prim, SumTermId, ProductTermId, F, A]) = fa.hmap(nt)
         }
     }
 
@@ -264,6 +264,8 @@ trait SchemaModule[R <: Realisation] {
 
   val R: R
 
+  import SchemaF._
+
   type RInterpreter[F[_]] = Interpreter[R.Prim, R.SumTermId, R.ProductTermId, F]
 
   type RSchema[F[_], A] = SchemaF[R.Prim, R.SumTermId, R.ProductTermId, F, A]
diff --git a/modules/play-json/src/main/scala/PlayJsonModule.scala b/modules/play-json/src/main/scala/PlayJsonModule.scala
index 09de750..be64f50 100644
--- a/modules/play-json/src/main/scala/PlayJsonModule.scala
+++ b/modules/play-json/src/main/scala/PlayJsonModule.scala
@@ -11,7 +11,7 @@ import _root_.play.api.libs.functional.syntax._
 
 trait PlayJsonModule[R <: Realisation] extends SchemaModule[R] {
 
-  import Schema._
+  import SchemaF._
 
   type LabelledSchema[A] = (Boolean, FSchema[R.Prim, R.SumTermId, R.ProductTermId, A])
 
diff --git a/modules/tests/src/main/scala/GenModuleExamples.scala b/modules/tests/src/main/scala/GenModuleExamples.scala
index 1507363..ab60c5c 100644
--- a/modules/tests/src/main/scala/GenModuleExamples.scala
+++ b/modules/tests/src/main/scala/GenModuleExamples.scala
@@ -15,7 +15,7 @@ trait PrimToGen {
       case JsonSchema.JsonString => arbitrary[String]
       case JsonSchema.JsonNumber => arbitrary[BigDecimal]
       case JsonSchema.JsonBool   => arbitrary[Boolean]
-      case JsonSchema.JsonNull   => arbitrary[Null]
+      case JsonSchema.JsonNull   => arbitrary[Unit]
     }
   }
 
diff --git a/modules/tests/src/main/scala/GenericGenModule.scala b/modules/tests/src/main/scala/GenericGenModule.scala
index effc7cd..a58ced9 100644
--- a/modules/tests/src/main/scala/GenericGenModule.scala
+++ b/modules/tests/src/main/scala/GenericGenModule.scala
@@ -32,8 +32,8 @@ trait GenericGenModule[R <: Realisation] extends GenericSchemaModule[R] {
 
   implicit final def algebra(
     implicit primNT: R.Prim ~> Gen
-  ): HAlgebra[RSchema, Gen] =
-    covariantTargetFunctor[Gen](
+  ): RInterpreter[Gen] = new Interpreter[R.Prim, R.SumTermId, R.ProductTermId, Gen] {
+    private val alg = covariantTargetFunctor[Gen](
       primNT,
       λ[Gen ~> λ[X => Gen[List[X]]]](x => Gen.listOf(x)),
       λ[RProductTerm[Gen, ?] ~> Gen](gen => gen.schema),
@@ -41,4 +41,6 @@ trait GenericGenModule[R <: Realisation] extends GenericSchemaModule[R] {
       Gen.const(())
     )
 
+    def interpret: Schema ~> Gen = cataNT(alg)
+  }
 }
diff --git a/modules/tests/src/main/scala/PlayJsonExamples.scala b/modules/tests/src/main/scala/PlayJsonExamples.scala
index ea09587..3ff2cc3 100644
--- a/modules/tests/src/main/scala/PlayJsonExamples.scala
+++ b/modules/tests/src/main/scala/PlayJsonExamples.scala
@@ -50,7 +50,6 @@ object PlayJsonExamples {
 
   def tests[T](harness: Harness[T]): T = {
     import harness._
-    import Schema._
     import module._
     import JsonSchema._
 
diff --git a/modules/tests/src/main/scala/ShowExamples.scala b/modules/tests/src/main/scala/ShowExamples.scala
index a214ab6..a43880b 100644
--- a/modules/tests/src/main/scala/ShowExamples.scala
+++ b/modules/tests/src/main/scala/ShowExamples.scala
@@ -9,10 +9,11 @@ import generic._
 
 object ShowExamples {
 
-  import JsonSchema._
-
   val showModule = new TestModule with ShowModule[JsonSchema.type] {
 
+    import SchemaF._
+    import JsonSchema._
+
     val primToShowNT = new (JsonSchema.Prim ~> Show) {
 
       def apply[A](fa: JsonSchema.Prim[A]): Show[A] =
@@ -20,9 +21,14 @@ object ShowExamples {
           case JsonNumber => Show.showFromToString[BigDecimal]
           case JsonBool   => Show.showFromToString[Boolean]
           case JsonString => Show.shows[String](s => s""""$s"""")
-          case JsonNull   => Show.shows[Null](_ => "null")
+          case JsonNull   => Show.shows[Unit](_ => "null")
         }
     }
+
+    implicit val interpreter = new Interpreter[R.Prim, R.SumTermId, R.ProductTermId, Show] {
+      private val alg               = showAlgebra(primToShowNT, identity[String], identity[String])
+      def interpret: Schema ~> Show = cataNT(alg)
+    }
   }
 
   def tests[T](harness: Harness[T]): T = {
@@ -33,8 +39,6 @@ object ShowExamples {
       test("commons Show Instance") { () =>
         {
 
-          implicit val alg = showAlgebra(primToShowNT, identity[String], identity[String])
-
           val testCases: List[(Person, String)] = List(
             Person(null, None)                                          -> """(name = ("null"), role = (()))""",
             Person("Alfred", None)                                      -> """(name = ("Alfred"), role = (()))""",