IsValueClass evidence

dataset/src/main/scala/frameless/IsValueClass.scala

@@ -0,0 +1,17 @@
+package frameless
+
+import shapeless._
+import shapeless.labelled.FieldType
+
+/** Evidence that `T` is a Value class */
+@annotation.implicitNotFound(msg = "${T} is not a Value class")
+final class IsValueClass[T] private() {}
+
+object IsValueClass {
+  /** Provides an evidence `A` is a Value class */
+  implicit def apply[A <: AnyVal, G <: ::[_, HNil], H <: ::[_ <: FieldType[_ <: Symbol, _], HNil]](
+    implicit
+      i0: LabelledGeneric.Aux[A, G],
+    i1: DropUnitValues.Aux[G, H]): IsValueClass[A] = new IsValueClass[A]
+
+}

dataset/src/main/scala/frameless/RecordEncoder.scala

@@ -188,7 +188,7 @@ object RecordFieldEncoder extends RecordFieldEncoderLowPriority {
    * @tparam K the key type for the fields
    * @tparam V the inner value type
    */
-  implicit def optionValueClass[F <: AnyVal, G <: ::[_, HNil], H <: ::[_ <: FieldType[_ <: Symbol, _], HNil], K <: Symbol, V, KS <: ::[_ <: Symbol, HNil]]
+  implicit def optionValueClass[F : IsValueClass, G <: ::[_, HNil], H <: ::[_ <: FieldType[_ <: Symbol, _], HNil], K <: Symbol, V, KS <: ::[_ <: Symbol, HNil]]
     (implicit
       i0: LabelledGeneric.Aux[F, G],
       i1: DropUnitValues.Aux[G, H],
@@ -229,7 +229,7 @@ object RecordFieldEncoder extends RecordFieldEncoderLowPriority {
    * @tparam H the single field of the value class (with guarantee it's not a `Unit` value)
    * @tparam V the inner value type
    */
-  implicit def valueClass[F <: AnyVal, G <: ::[_, HNil], H <: ::[_, HNil], V]
+  implicit def valueClass[F : IsValueClass, G <: ::[_, HNil], H <: ::[_, HNil], V]
     (implicit
       i0: LabelledGeneric.Aux[F, G],
       i1: DropUnitValues.Aux[G, H],

dataset/src/main/scala/frameless/TypedColumn.scala

@@ -31,7 +31,7 @@ sealed class TypedColumn[T, U](expr: Expression)(
 
   override def typed[W, U1: TypedEncoder](c: Column): TypedColumn[W, U1] = c.typedColumn
 
-  override def lit[U1: TypedEncoder](c: U1): TypedColumn[T,U1] = flit(c)
+  override def lit[U1: TypedEncoder](c: U1): TypedColumn[T, U1] = flit(c)
 }
 
 /** Expression used in `agg`-like constructions.

dataset/src/main/scala/frameless/functions/Lit.scala

@@ -5,16 +5,15 @@ import org.apache.spark.sql.catalyst.expressions.codegen._
 import org.apache.spark.sql.catalyst.expressions.{Expression, NonSQLExpression}
 import org.apache.spark.sql.types.DataType
 
-case class Lit[T <: AnyVal] private[frameless] (
-    val dataType: DataType,
-    val nullable: Boolean,
+private[frameless] case class Lit[T <: AnyVal](
+    dataType: DataType,
+    nullable: Boolean,
     toCatalyst: CodegenContext => ExprCode,
     show: () => String)
     extends Expression
     with NonSQLExpression {
   override def toString: String = s"FramelessLit(${show()})"
 
-  @SuppressWarnings(Array("AsInstanceOf", "MethodReturningAny"))
   def eval(input: InternalRow): Any = {
     val ctx = new CodegenContext()
     val eval = genCode(ctx)

dataset/src/main/scala/frameless/functions/package.scala

@@ -20,8 +20,8 @@ package object functions extends Udf with UnaryFunctions {
     *
     * apache/spark
     */
-  def litAggr[A: TypedEncoder, T](value: A): TypedAggregate[T, A] =
-    new TypedAggregate[T,A](lit(value).expr)
+  def litAggr[A, T](value: A)(implicit i0: TypedEncoder[A], i1: Refute[IsValueClass[A]]): TypedAggregate[T, A] =
+    new TypedAggregate[T, A](lit(value).expr)
 
   /** Creates a [[frameless.TypedColumn]] of literal value. If A is to be encoded using an Injection make
     * sure the injection instance is in scope.
@@ -41,7 +41,7 @@ package object functions extends Udf with UnaryFunctions {
       val expr = new Literal(value, encoder.jvmRepr)
 
       new TypedColumn[T, A](
-        new functions.Lit(
+        Lit(
           dataType = encoder.catalystRepr,
           nullable = encoder.nullable,
           toCatalyst = encoder.toCatalyst(expr).genCode(_),
@@ -57,7 +57,7 @@ package object functions extends Udf with UnaryFunctions {
     * @tparam A the value class
     * @tparam T the row type
     */
-  def litValue[A <: AnyVal, T, G <: ::[_, HNil], H <: ::[_ <: FieldType[_ <: Symbol, _], HNil], V, VS <: HList](value: A)(
+  def litValue[A : IsValueClass, T, G <: ::[_, HNil], H <: ::[_ <: FieldType[_ <: Symbol, _], HNil], V, VS <: HList](value: A)(
     implicit
       i0: LabelledGeneric.Aux[A, G],
       i1: DropUnitValues.Aux[G, H],
@@ -78,7 +78,7 @@ package object functions extends Udf with UnaryFunctions {
       RecordFieldEncoder.valueClass[A, G, H, V].encoder
 
     new TypedColumn[T, A](
-      new Lit(
+      Lit(
         dataType = i5.catalystRepr,
         nullable = i5.nullable,
         toCatalyst = i5.toCatalyst(expr).genCode(_),

dataset/src/test/scala/frameless/BitwiseTests.scala

@@ -4,7 +4,7 @@ import org.scalacheck.Prop
 import org.scalacheck.Prop._
 import org.scalatest.matchers.should.Matchers
 
-class BitwiseTests extends TypedDatasetSuite with Matchers{
+class BitwiseTests extends TypedDatasetSuite with Matchers {
 
   /**
     * providing instances with implementations for bitwise operations since in the tests

dataset/src/test/scala/frameless/IsValueClassTests.scala

@@ -0,0 +1,31 @@
+package frameless
+
+import shapeless.Refute
+import shapeless.test.illTyped
+
+import org.scalatest.funsuite.AnyFunSuite
+import org.scalatest.matchers.should.Matchers
+
+final class IsValueClassTests extends AnyFunSuite with Matchers {
+  test("Case class is not Value class") {
+    illTyped("IsValueClass[P]")
+    illTyped("IsValueClass[Q]")
+  }
+
+  test("Scala value type is not Value class (excluded)") {
+    illTyped("implicitly[IsValueClass[Double]]")
+    illTyped("implicitly[IsValueClass[Float]]")
+    illTyped("implicitly[IsValueClass[Long]]")
+    illTyped("implicitly[IsValueClass[Int]]")
+    illTyped("implicitly[IsValueClass[Char]]")
+    illTyped("implicitly[IsValueClass[Short]]")
+    illTyped("implicitly[IsValueClass[Byte]]")
+    illTyped("implicitly[IsValueClass[Unit]]")
+    illTyped("implicitly[IsValueClass[Boolean]]")
+  }
+
+  test("Value class evidence") {
+    implicitly[IsValueClass[RecordEncoderTests.Name]]
+    illTyped("implicitly[Refute[IsValueClass[RecordEncoderTests.Name]]]")
+  }
+}

dataset/src/test/scala/frameless/LitTests.scala

@@ -1,6 +1,6 @@
 package frameless
 
-import frameless.functions.{ lit, litValue }
+import frameless.functions.lit
 
 import org.scalatest.matchers.should.Matchers
 
@@ -9,7 +9,7 @@ import org.scalacheck.Prop, Prop._
 import RecordEncoderTests.Name
 
 class LitTests extends TypedDatasetSuite with Matchers {
-  def prop[A: TypedEncoder](value: A): Prop = {
+  def prop[A: TypedEncoder](value: A)(implicit i0: shapeless.Refute[IsValueClass[A]]): Prop = {
     val df: TypedDataset[Int] = TypedDataset.create(1 :: Nil)
 
     val l: TypedColumn[Int, A] = lit(value)
@@ -65,7 +65,7 @@ class LitTests extends TypedDatasetSuite with Matchers {
 
     val lorem = new Name("Lorem")
 
-    ds.withColumnReplaced('name, litValue(lorem)).
+    ds.withColumnReplaced('name, functions.litValue(lorem)).
       collect.run() shouldBe initial.map(_.copy(name = lorem))
   }