diff --git a/core/src/main/scala/com/salesforce/op/dsl/RichDateFeature.scala b/core/src/main/scala/com/salesforce/op/dsl/RichDateFeature.scala
index ee8d1f1e20..26f4afc71c 100644
--- a/core/src/main/scala/com/salesforce/op/dsl/RichDateFeature.scala
+++ b/core/src/main/scala/com/salesforce/op/dsl/RichDateFeature.scala
@@ -56,7 +56,7 @@ trait RichDateFeature {
       f.transformWith(
         new UnaryLambdaTransformer[Date, DateList](
           operationName = "dateToList",
-          RichDateFeatureLambdas.toDateList
+          new RichDateFeatureLambdas.ToDateList
         )
       )
     }
@@ -137,7 +137,7 @@ trait RichDateFeature {
       f.transformWith(
         new UnaryLambdaTransformer[DateTime, DateTimeList](
           operationName = "dateTimeToList",
-          RichDateFeatureLambdas.toDateTimeList
+          new RichDateFeatureLambdas.ToDateTimeList
         )
       )
     }
@@ -204,7 +204,13 @@ trait RichDateFeature {
 }
 
 object RichDateFeatureLambdas {
-  def toDateList: Date => DateList = (x: Date) => x.value.toSeq.toDateList
 
-  def toDateTimeList: DateTime => DateTimeList = (x: DateTime) => x.value.toSeq.toDateTimeList
+  class ToDateList extends Function1[Date, DateList] with Serializable {
+    def apply(v: Date): DateList = v.value.toSeq.toDateList
+  }
+
+  class ToDateTimeList extends Function1[Date, DateTimeList] with Serializable {
+    def apply(v: Date): DateTimeList = v.value.toSeq.toDateTimeList
+  }
+
 }
diff --git a/core/src/main/scala/com/salesforce/op/dsl/RichMapFeature.scala b/core/src/main/scala/com/salesforce/op/dsl/RichMapFeature.scala
index 55c93d44f2..d602ec1656 100644
--- a/core/src/main/scala/com/salesforce/op/dsl/RichMapFeature.scala
+++ b/core/src/main/scala/com/salesforce/op/dsl/RichMapFeature.scala
@@ -30,7 +30,6 @@
 
 package com.salesforce.op.dsl
 
-import com.salesforce.op.dsl.RichMapFeatureLambdas._
 import com.salesforce.op.features.FeatureLike
 import com.salesforce.op.features.types._
 import com.salesforce.op.stages.impl.feature._
@@ -1098,9 +1097,10 @@ trait RichMapFeature {
      * @return prediction, rawPrediction, probability
      */
     def tupled(): (FeatureLike[RealNN], FeatureLike[OPVector], FeatureLike[OPVector]) = {
-      (f.map[RealNN](predictionToRealNN),
-        f.map[OPVector](predictionToRaw),
-        f.map[OPVector](predictionToProbability)
+      import RichMapFeatureLambdas._
+      (f.map[RealNN](new PredictionToRealNN),
+        f.map[OPVector](new PredictionToRaw),
+        f.map[OPVector](new PredictionToProbability)
       )
     }
 
@@ -1121,11 +1121,17 @@ trait RichMapFeature {
 
 object RichMapFeatureLambdas {
 
-  def predictionToRealNN: Prediction => RealNN = _.prediction.toRealNN
+  class PredictionToRealNN extends Function1[Prediction, RealNN] with Serializable {
+    def apply(p: Prediction): RealNN = p.prediction.toRealNN
+  }
 
-  def predictionToRaw: Prediction => OPVector = p => Vectors.dense(p.rawPrediction).toOPVector
+  class PredictionToRaw extends Function1[Prediction, OPVector] with Serializable {
+    def apply(p: Prediction): OPVector = Vectors.dense(p.rawPrediction).toOPVector
+  }
 
-  def predictionToProbability: Prediction => OPVector = p => Vectors.dense(p.probability).toOPVector
+  class PredictionToProbability extends Function1[Prediction, OPVector] with Serializable {
+    def apply(p: Prediction): OPVector = Vectors.dense(p.probability).toOPVector
+  }
 
 }
 
diff --git a/core/src/main/scala/com/salesforce/op/dsl/RichTextFeature.scala b/core/src/main/scala/com/salesforce/op/dsl/RichTextFeature.scala
index fa175d8153..bd78b58aa1 100644
--- a/core/src/main/scala/com/salesforce/op/dsl/RichTextFeature.scala
+++ b/core/src/main/scala/com/salesforce/op/dsl/RichTextFeature.scala
@@ -37,6 +37,8 @@ import com.salesforce.op.stages.impl.feature._
 import com.salesforce.op.utils.text._
 
 import scala.reflect.runtime.universe.TypeTag
+
+
 trait RichTextFeature {
   self: RichFeature =>
 
@@ -48,7 +50,7 @@ trait RichTextFeature {
      *
      * @return A new MultiPickList feature
      */
-    def toMultiPickList: FeatureLike[MultiPickList] = f.map[MultiPickList](textToMultiPickList)
+    def toMultiPickList: FeatureLike[MultiPickList] = f.map[MultiPickList](new TextToMultiPickList)
 
 
     /**
@@ -560,14 +562,14 @@ trait RichTextFeature {
      *
      * @return email prefix
      */
-    def toEmailPrefix: FeatureLike[Text] = f.map[Text](emailToPrefix, "prefix")
+    def toEmailPrefix: FeatureLike[Text] = f.map[Text](new EmailPrefixToText, "prefix")
 
     /**
      * Extract email domains
      *
      * @return email domain
      */
-    def toEmailDomain: FeatureLike[Text] = f.map[Text](emailToDomain, "domain")
+    def toEmailDomain: FeatureLike[Text] = f.map[Text](new EmailDomainToText, "domain")
 
     /**
      * Check if email is valid
@@ -600,7 +602,7 @@ trait RichTextFeature {
       others: Array[FeatureLike[Email]] = Array.empty,
       maxPctCardinality: Double = OpOneHotVectorizer.MaxPctCardinality
     ): FeatureLike[OPVector] = {
-      val domains = (f +: others).map(_.map[PickList](emailToPickList))
+      val domains = (f +: others).map(_.map[PickList](new EmailDomainToPickList))
       domains.head.pivot(others = domains.tail, topK = topK, minSupport = minSupport, cleanText = cleanText,
         trackNulls = trackNulls, maxPctCardinality = maxPctCardinality
       )
@@ -613,19 +615,19 @@ trait RichTextFeature {
     /**
      * Extract url domain, i.e. salesforce.com, data.com etc.
      */
-    def toDomain: FeatureLike[Text] = f.map[Text](urlToDomain, "urlDomain")
+    def toDomain: FeatureLike[Text] = f.map[Text](new URLDomainToText, "urlDomain")
 
     /**
      * Extracts url protocol, i.e. http, https, ftp etc.
      */
-    def toProtocol: FeatureLike[Text] = f.map[Text](urlToProtocol, "urlProtocol")
+    def toProtocol: FeatureLike[Text] = f.map[Text](new URLProtocolToText, "urlProtocol")
 
     /**
      * Verifies if the url is of correct form of "Uniform Resource Identifiers (URI): Generic Syntax"
      * RFC2396 (http://www.ietf.org/rfc/rfc2396.txt)
      * Default valid protocols are: http, https, ftp.
      */
-    def isValidUrl: FeatureLike[Binary] = f.exists(urlIsValid)
+    def isValidUrl: FeatureLike[Binary] = f.exists(new URLIsValid)
 
     /**
      * Converts a sequence of [[URL]] features into a vector, extracting the domains of the valid urls
@@ -650,7 +652,7 @@ trait RichTextFeature {
       others: Array[FeatureLike[URL]] = Array.empty,
       maxPctCardinality: Double = OpOneHotVectorizer.MaxPctCardinality
     ): FeatureLike[OPVector] = {
-      val domains = (f +: others).map(_.map[PickList](urlToPickList))
+      val domains = (f +: others).map(_.map[PickList](new URLDomainToPickList))
       domains.head.pivot(others = domains.tail, topK = topK, minSupport = minSupport, cleanText = cleanText,
         trackNulls = trackNulls, maxPctCardinality = maxPctCardinality
       )
@@ -697,7 +699,7 @@ trait RichTextFeature {
     ): FeatureLike[OPVector] = {
 
       val feats: Array[FeatureLike[PickList]] =
-        (f +: others).map(_.detectMimeTypes(typeHint).map[PickList](textToPickList))
+        (f +: others).map(_.detectMimeTypes(typeHint).map[PickList](new TextToPickList))
 
       feats.head.vectorize(
         topK = topK, minSupport = minSupport, cleanText = cleanText, trackNulls = trackNulls, others = feats.tail,
@@ -801,22 +803,40 @@ trait RichTextFeature {
 
 object RichTextFeatureLambdas {
 
-  def emailToPickList: Email => PickList = _.domain.toPickList
+  class EmailDomainToPickList extends Function1[Email, PickList] with Serializable {
+    def apply(v: Email): PickList = v.domain.toPickList
+  }
 
-  def emailToPrefix: Email => Text = _.prefix.toText
+  class EmailDomainToText extends Function1[Email, Text] with Serializable {
+    def apply(v: Email): Text = v.domain.toText
+  }
 
-  def emailToDomain: Email => Text = _.domain.toText
+  class EmailPrefixToText extends Function1[Email, Text] with Serializable {
+    def apply(v: Email): Text = v.prefix.toText
+  }
 
-  def urlToPickList: URL => PickList = (v: URL) => if (v.isValid) v.domain.toPickList else PickList.empty
+  class URLDomainToPickList extends Function1[URL, PickList] with Serializable {
+    def apply(v: URL): PickList = if (v.isValid) v.domain.toPickList else PickList.empty
+  }
 
-  def urlToDomain: URL => Text = _.domain.toText
+  class URLDomainToText extends Function1[URL, Text] with Serializable {
+    def apply(v: URL): Text = v.domain.toText
+  }
 
-  def urlToProtocol: URL => Text = _.protocol.toText
+  class URLProtocolToText extends Function1[URL, Text] with Serializable {
+    def apply(v: URL): Text = v.protocol.toText
+  }
 
-  def urlIsValid: URL => Boolean = _.isValid
+  class URLIsValid extends Function1[URL, Boolean] with Serializable {
+    def apply(v: URL): Boolean = v.isValid
+  }
 
-  def textToPickList: Text => PickList = _.value.toPickList
+  class TextToPickList extends Function1[Text, PickList] with Serializable {
+    def apply(v: Text): PickList = v.value.toPickList
+  }
 
-  def textToMultiPickList: Text => MultiPickList = _.value.toSet[String].toMultiPickList
+  class TextToMultiPickList extends Function1[Text, MultiPickList] with Serializable {
+    def apply(v: Text): MultiPickList = v.value.toSet[String].toMultiPickList
+  }
 
 }
diff --git a/core/src/main/scala/com/salesforce/op/stages/impl/feature/EmailToPickListMapTransformer.scala b/core/src/main/scala/com/salesforce/op/stages/impl/feature/EmailToPickListMapTransformer.scala
index 748bdb4058..31934e1418 100644
--- a/core/src/main/scala/com/salesforce/op/stages/impl/feature/EmailToPickListMapTransformer.scala
+++ b/core/src/main/scala/com/salesforce/op/stages/impl/feature/EmailToPickListMapTransformer.scala
@@ -41,10 +41,14 @@ class EmailToPickListMapTransformer(uid: String = UID[EmailToPickListMapTransfor
     operationName = "emailToPickListMap",
     transformer = new UnaryLambdaTransformer[Email, PickList](
       operationName = "emailToPickList",
-      transformFn = EmailToPickListMapTransformer.emailToPickList
+      transformFn = new EmailToPickListMapTransformer.EmailToPickList
     )
   )
 
 object EmailToPickListMapTransformer {
-  def emailToPickList: Email => PickList = email => email.domain.toPickList
+
+  class EmailToPickList extends Function1[Email, PickList] with Serializable {
+    def apply(v: Email): PickList = v.domain.toPickList
+  }
+
 }
diff --git a/core/src/main/scala/com/salesforce/op/stages/impl/feature/ScalerTransformer.scala b/core/src/main/scala/com/salesforce/op/stages/impl/feature/ScalerTransformer.scala
index 437737d02a..14419bec77 100644
--- a/core/src/main/scala/com/salesforce/op/stages/impl/feature/ScalerTransformer.scala
+++ b/core/src/main/scala/com/salesforce/op/stages/impl/feature/ScalerTransformer.scala
@@ -33,10 +33,8 @@ package com.salesforce.op.stages.impl.feature
 import com.salesforce.op.UID
 import com.salesforce.op.features.types._
 import com.salesforce.op.stages.base.unary.UnaryTransformer
-import com.salesforce.op.utils.json.{JsonLike, JsonUtils}
+import com.salesforce.op.utils.json.JsonUtils
 import org.apache.spark.sql.types.{Metadata, MetadataBuilder}
-import org.json4s.JsonAST.{JField, JNothing}
-import org.json4s.{CustomSerializer, JObject}
 
 import scala.reflect.runtime.universe.TypeTag
 import scala.util.{Failure, Try}
diff --git a/core/src/main/scala/com/salesforce/op/stages/impl/feature/ToOccurTransformer.scala b/core/src/main/scala/com/salesforce/op/stages/impl/feature/ToOccurTransformer.scala
index 066e780a58..de92c524cd 100644
--- a/core/src/main/scala/com/salesforce/op/stages/impl/feature/ToOccurTransformer.scala
+++ b/core/src/main/scala/com/salesforce/op/stages/impl/feature/ToOccurTransformer.scala
@@ -47,7 +47,7 @@ import scala.reflect.runtime.universe.TypeTag
 class ToOccurTransformer[I <: FeatureType]
 (
   uid: String = UID[ToOccurTransformer[I]],
-  val matchFn: I => Boolean = ToOccurTransformer.defaultMatches[I]
+  val matchFn: I => Boolean = new ToOccurTransformer.DefaultMatches[I]
 )(implicit tti: TypeTag[I])
   extends UnaryTransformer[I, RealNN](operationName = "toOccur", uid = uid) {
 
@@ -60,11 +60,13 @@ class ToOccurTransformer[I <: FeatureType]
 
 object ToOccurTransformer {
 
-  def defaultMatches[T <: FeatureType]: T => Boolean = {
-    case num: OPNumeric[_] if num.nonEmpty => num.toDouble.get > 0.0
-    case text: Text if text.nonEmpty => text.value.get.length > 0
-    case collection: OPCollection => collection.nonEmpty
-    case _ => false
+  class DefaultMatches[T <: FeatureType] extends Function1[T, Boolean] with Serializable {
+    def apply(t: T): Boolean = t match {
+      case num: OPNumeric[_] if num.nonEmpty => num.toDouble.get > 0.0
+      case text: Text if text.nonEmpty => text.value.get.length > 0
+      case collection: OPCollection => collection.nonEmpty
+      case _ => false
+    }
   }
 
 }
diff --git a/core/src/test/scala/com/salesforce/op/OpWorkflowModelReaderWriterTest.scala b/core/src/test/scala/com/salesforce/op/OpWorkflowModelReaderWriterTest.scala
index d65b5c2352..977c19270a 100644
--- a/core/src/test/scala/com/salesforce/op/OpWorkflowModelReaderWriterTest.scala
+++ b/core/src/test/scala/com/salesforce/op/OpWorkflowModelReaderWriterTest.scala
@@ -141,7 +141,7 @@ class OpWorkflowModelReaderWriterTest
   }
 
   trait SwSingleStageFlow {
-    val vec = FeatureBuilder.OPVector[Passenger].extract(OpWorkflowModelReaderWriterTest.emptyVectorFn).asPredictor
+    val vec = FeatureBuilder.OPVector[Passenger].extract(new OpWorkflowModelReaderWriterTest.EmptyVectorFn).asPredictor
     val scaler = new StandardScaler().setWithStd(false).setWithMean(false)
     val schema = FeatureSparkTypes.toStructType(vec)
     val data = spark.createDataFrame(List(Row(Vectors.dense(1.0))).asJava, schema)
@@ -158,12 +158,12 @@ class OpWorkflowModelReaderWriterTest
 
   trait OldVectorizedFlow extends UIDReset {
     val cat = Seq(gender, boarded, height, age, description).transmogrify()
-    val catHead = cat.map[Real](OpWorkflowModelReaderWriterTest.catHeadFn)
+    val catHead = cat.map[Real](new OpWorkflowModelReaderWriterTest.CatHeadFn)
     val wf = new OpWorkflow().setParameters(workflowParams).setResultFeatures(catHead)
   }
 
   trait VectorizedFlow extends UIDReset {
-    val catHead = rawFeatures.transmogrify().map[Real](OpWorkflowModelReaderWriterTest.catHeadFn)
+    val catHead = rawFeatures.transmogrify().map[Real](new OpWorkflowModelReaderWriterTest.CatHeadFn)
     val wf = new OpWorkflow().setParameters(workflowParams).setResultFeatures(catHead)
   }
 
@@ -386,6 +386,13 @@ trait UIDReset {
 }
 
 object OpWorkflowModelReaderWriterTest {
-  def catHeadFn: OPVector => Real = v => Real(v.value.toArray.headOption)
-  def emptyVectorFn: Passenger => OPVector = _ => OPVector.empty
+
+  class CatHeadFn extends Function1[OPVector, Real] with Serializable {
+    def apply(v: OPVector): Real = Real(v.value.toArray.headOption)
+  }
+
+  class EmptyVectorFn extends Function1[Passenger, OPVector] with Serializable {
+    def apply(v: Passenger): OPVector = OPVector.empty
+  }
+
 }
diff --git a/core/src/test/scala/com/salesforce/op/stages/Lambdas.scala b/core/src/test/scala/com/salesforce/op/stages/Lambdas.scala
index 9ffb467bd8..4492350696 100644
--- a/core/src/test/scala/com/salesforce/op/stages/Lambdas.scala
+++ b/core/src/test/scala/com/salesforce/op/stages/Lambdas.scala
@@ -34,38 +34,37 @@ import com.salesforce.op.features.types.Real
 import com.salesforce.op.features.types._
 
 object Lambdas {
-  def fncUnary: Real => Real = (x: Real) => x.v.map(_ * 0.1234).toReal
 
-  def fncSequence: Seq[DateList] => Real = (x: Seq[DateList]) => {
-    val v = x.foldLeft(0.0)((a, b) => a + b.value.sum)
-    Math.round(v / 1E6).toReal
+  class FncSequence extends Function1[Seq[DateList], Real] with Serializable {
+    def apply(x: Seq[DateList]): Real = {
+      val v = x.foldLeft(0.0)((a, b) => a + b.value.sum)
+      Math.round(v / 1E6).toReal
+    }
   }
 
-  def fncBinarySequence: (Real, Seq[DateList]) => Real = (y: Real, x: Seq[DateList]) => {
-    val v = x.foldLeft(0.0)((a, b) => a + b.value.sum)
-    (Math.round(v / 1E6) + y.value.getOrElse(0.0)).toReal
+  class FncBinarySequence extends Function2[Real, Seq[DateList], Real] with Serializable {
+    def apply(y: Real, x: Seq[DateList]): Real = {
+      val v = x.foldLeft(0.0)((a, b) => a + b.value.sum)
+      (Math.round(v / 1E6) + y.value.getOrElse(0.0)).toReal
+    }
   }
 
-  def fncBinary: (Real, Real) => Real = (x: Real, y: Real) => (
-    for {
-      yv <- y.value
-      xv <- x.value
-    } yield xv * yv
-    ).toReal
+  class FncUnary extends Function1[Real, Real] with Serializable {
+    def apply(x: Real): Real = x.v.map(_ * 0.1234).toReal
+  }
 
-  def fncTernary: (Real, Real, Real) => Real = (x: Real, y: Real, z: Real) =>
-    (for {
-      xv <- x.value
-      yv <- y.value
-      zv <- z.value
-    } yield xv * yv + zv).toReal
+  class FncBinary extends Function2[Real, Real, Real] with Serializable {
+    def apply(x: Real, y: Real): Real = (for {yv <- y.value; xv <- x.value} yield xv * yv).toReal
+  }
 
-  def fncQuaternary: (Real, Real, Text, Real) => Real = (x: Real, y: Real, t: Text, z: Real) =>
-    (for {
-      xv <- x.value
-      yv <- y.value
-      tv <- t.value
-      zv <- z.value
-    } yield xv * yv + zv * tv.length).toReal
+  class FncTernary extends Function3[Real, Real, Real, Real] with Serializable {
+    def apply(x: Real, y: Real, z: Real): Real =
+      (for {yv <- y.value; xv <- x.value; zv <- z.value} yield xv * yv + zv).toReal
+  }
+
+  class FncQuaternary extends Function4[Real, Real, Text, Real, Real] with Serializable {
+    def apply(x: Real, y: Real, t: Text, z: Real): Real =
+      (for {yv <- y.value; xv <- x.value; tv <- t.value; zv <- z.value} yield xv * yv + zv * tv.length).toReal
+  }
 
 }
diff --git a/core/src/test/scala/com/salesforce/op/stages/OpPipelineStagesTest.scala b/core/src/test/scala/com/salesforce/op/stages/OpPipelineStagesTest.scala
index 8e7c862f56..32d1984859 100644
--- a/core/src/test/scala/com/salesforce/op/stages/OpPipelineStagesTest.scala
+++ b/core/src/test/scala/com/salesforce/op/stages/OpPipelineStagesTest.scala
@@ -134,7 +134,7 @@ class OpPipelineStagesTest
 
   val testOp = new com.salesforce.op.stages.base.unary.UnaryLambdaTransformer[Real, Real](
     operationName = "test",
-    transformFn = OpPipelineStagesTest.fnc0,
+    transformFn = new OpPipelineStagesTest.RealIdentity,
     uid = "myID"
   )
 
@@ -162,7 +162,10 @@ class OpPipelineStagesTest
 }
 
 object OpPipelineStagesTest {
-  def fnc0: Real => Real = x => x
+
+  class RealIdentity extends Function1[Real, Real] with Serializable {
+    def apply(v: Real): Real = v
+  }
 
   class TestStage(implicit val tto: TypeTag[RealNN], val ttov: TypeTag[RealNN#Value])
     extends Pipeline with OpPipelineStage1[RealNN, RealNN] {
diff --git a/core/src/test/scala/com/salesforce/op/stages/OpTransformerBinaryReaderWriterTest.scala b/core/src/test/scala/com/salesforce/op/stages/OpTransformerBinaryReaderWriterTest.scala
index 91ce639439..f585e8375f 100644
--- a/core/src/test/scala/com/salesforce/op/stages/OpTransformerBinaryReaderWriterTest.scala
+++ b/core/src/test/scala/com/salesforce/op/stages/OpTransformerBinaryReaderWriterTest.scala
@@ -44,7 +44,7 @@ class OpTransformerBinaryReaderWriterTest extends OpPipelineStageReaderWriterTes
   val stage =
     new BinaryLambdaTransformer[Real, Real, Real](
       operationName = "test",
-      transformFn = Lambdas.fncBinary
+      transformFn = new Lambdas.FncBinary
     ).setInput(weight, age).setMetadata(meta)
 
   val expected = Array(8600.toReal, 134.toReal, Real.empty, 2574.toReal, Real.empty, 2144.toReal)
diff --git a/core/src/test/scala/com/salesforce/op/stages/OpTransformerBinarySequenceReaderWriterTest.scala b/core/src/test/scala/com/salesforce/op/stages/OpTransformerBinarySequenceReaderWriterTest.scala
index fc169b2dc0..cddf0a919d 100644
--- a/core/src/test/scala/com/salesforce/op/stages/OpTransformerBinarySequenceReaderWriterTest.scala
+++ b/core/src/test/scala/com/salesforce/op/stages/OpTransformerBinarySequenceReaderWriterTest.scala
@@ -44,7 +44,7 @@ class OpTransformerBinarySequenceReaderWriterTest extends OpPipelineStageReaderW
   val stage =
     new BinarySequenceLambdaTransformer[Real, DateList, Real](
       operationName = "test",
-      transformFn = Lambdas.fncBinarySequence
+      transformFn = new Lambdas.FncBinarySequence
     ).setInput(weight, boarded).setMetadata(meta)
 
   val expected = Array(3114.toReal, 1538.toReal, 0.toReal, 1549.toReal, 1567.toReal, 1538.toReal)
diff --git a/core/src/test/scala/com/salesforce/op/stages/OpTransformerQuaternaryReaderWriterTest.scala b/core/src/test/scala/com/salesforce/op/stages/OpTransformerQuaternaryReaderWriterTest.scala
index ff839e6e25..fa338c6fdf 100644
--- a/core/src/test/scala/com/salesforce/op/stages/OpTransformerQuaternaryReaderWriterTest.scala
+++ b/core/src/test/scala/com/salesforce/op/stages/OpTransformerQuaternaryReaderWriterTest.scala
@@ -44,7 +44,7 @@ class OpTransformerQuaternaryReaderWriterTest extends OpPipelineStageReaderWrite
   val stage =
     new QuaternaryLambdaTransformer[Real, Real, Text, Real, Real](
       operationName = "test",
-      transformFn = Lambdas.fncQuaternary,
+      transformFn = new Lambdas.FncQuaternary,
       uid = "uid_1234"
     ).setInput(weight, age, description, weight).setMetadata(meta)
 
diff --git a/core/src/test/scala/com/salesforce/op/stages/OpTransformerReaderWriterTest.scala b/core/src/test/scala/com/salesforce/op/stages/OpTransformerReaderWriterTest.scala
index 3548301670..c4243b8c5b 100644
--- a/core/src/test/scala/com/salesforce/op/stages/OpTransformerReaderWriterTest.scala
+++ b/core/src/test/scala/com/salesforce/op/stages/OpTransformerReaderWriterTest.scala
@@ -44,7 +44,7 @@ class OpTransformerReaderWriterTest extends OpPipelineStageReaderWriterTest {
   val stage =
     new UnaryLambdaTransformer[Real, Real](
       operationName = "test",
-      transformFn = Lambdas.fncUnary,
+      transformFn = new Lambdas.FncUnary,
       uid = "uid_1234"
     ).setInput(weight).setMetadata(meta)
 
diff --git a/core/src/test/scala/com/salesforce/op/stages/OpTransformerSequenceReaderWriterTest.scala b/core/src/test/scala/com/salesforce/op/stages/OpTransformerSequenceReaderWriterTest.scala
index c6886170bd..9db2fafa82 100644
--- a/core/src/test/scala/com/salesforce/op/stages/OpTransformerSequenceReaderWriterTest.scala
+++ b/core/src/test/scala/com/salesforce/op/stages/OpTransformerSequenceReaderWriterTest.scala
@@ -44,7 +44,7 @@ class OpTransformerSequenceReaderWriterTest extends OpPipelineStageReaderWriterT
   val stage =
     new SequenceLambdaTransformer[DateList, Real](
       operationName = "test",
-      transformFn = Lambdas.fncSequence,
+      transformFn = new Lambdas.FncSequence,
       uid = "uid_1234"
     ).setInput(boarded).setMetadata(meta)
 
diff --git a/core/src/test/scala/com/salesforce/op/stages/OpTransformerTernaryReaderWriterTest.scala b/core/src/test/scala/com/salesforce/op/stages/OpTransformerTernaryReaderWriterTest.scala
index 3d2cbbe708..5ca0c09a91 100644
--- a/core/src/test/scala/com/salesforce/op/stages/OpTransformerTernaryReaderWriterTest.scala
+++ b/core/src/test/scala/com/salesforce/op/stages/OpTransformerTernaryReaderWriterTest.scala
@@ -44,7 +44,7 @@ class OpTransformerTernaryReaderWriterTest extends OpPipelineStageReaderWriterTe
   val stage =
     new  TernaryLambdaTransformer[Real, Real, Real, Real](
       operationName = "test",
-      transformFn = Lambdas.fncTernary,
+      transformFn = new Lambdas.FncTernary,
       uid = "uid_1234"
     ).setInput(weight, age, weight).setMetadata(meta)
 
diff --git a/core/src/test/scala/com/salesforce/op/stages/impl/feature/DropIndicesByTransformerTest.scala b/core/src/test/scala/com/salesforce/op/stages/impl/feature/DropIndicesByTransformerTest.scala
index c0d0116630..44d645c708 100644
--- a/core/src/test/scala/com/salesforce/op/stages/impl/feature/DropIndicesByTransformerTest.scala
+++ b/core/src/test/scala/com/salesforce/op/stages/impl/feature/DropIndicesByTransformerTest.scala
@@ -54,9 +54,9 @@ class DropIndicesByTransformerTest extends OpTransformerSpec[OPVector, DropIndic
     val (data, v) = TestFeatureBuilder(vecData)
     val meta = OpVectorMetadata(v.name, Array(TransientFeature(v).toColumnMetaData()), Map.empty).toMetadata
     val inputData = data.withColumn(v.name, col(v.name).as(v.name, meta))
-    val stage = new DropIndicesByTransformer(
-      DropIndicesByTransformerTest.matchFn
-    ).setInput(v).setInputSchema(inputData.schema)
+    val stage =
+      new DropIndicesByTransformer(new DropIndicesByTransformerTest.MatchFn)
+        .setInput(v).setInputSchema(inputData.schema)
     inputData -> stage
   }
 
@@ -85,7 +85,7 @@ class DropIndicesByTransformerTest extends OpTransformerSpec[OPVector, DropIndic
     val rawMeta = OpVectorMetadata(vectorizedPicklist.name, vectorizedPicklist.originStage.getMetadata())
     val trimmedMeta = OpVectorMetadata(materializedFeatures.schema(prunedVector.name))
     rawMeta.columns.length - 1 shouldBe trimmedMeta.columns.length
-    trimmedMeta.columns.foreach(_.indicatorValue == "Red" shouldBe false)
+    trimmedMeta.columns.foreach(_.indicatorValue.contains("Red") shouldBe false)
   }
 
   it should "work with its shortcut" in {
@@ -109,12 +109,15 @@ class DropIndicesByTransformerTest extends OpTransformerSpec[OPVector, DropIndic
     val nonSer = new NonSerializable(5)
     val vectorizedPicklist = picklistFeature.vectorize(topK = 10, minSupport = 3, cleanText = false)
     intercept[IllegalArgumentException](
-      vectorizedPicklist.dropIndicesBy(_.indicatorValue.get == nonSer.in)
+      vectorizedPicklist.dropIndicesBy(_.indicatorValue.get == nonSer.in.toString)
     ).getMessage shouldBe "Provided function is not serializable"
   }
 
 }
 
 object DropIndicesByTransformerTest {
-  def matchFn: OpVectorColumnMetadata => Boolean = _.isNullIndicator
+
+  class MatchFn extends Function1[OpVectorColumnMetadata, Boolean] with Serializable {
+    def apply(m: OpVectorColumnMetadata): Boolean = m.isNullIndicator
+  }
 }
diff --git a/features/src/test/scala/com/salesforce/op/stages/base/binary/BinaryTransformerTest.scala b/features/src/test/scala/com/salesforce/op/stages/base/binary/BinaryTransformerTest.scala
index d92ef5641f..bb628b3ae1 100644
--- a/features/src/test/scala/com/salesforce/op/stages/base/binary/BinaryTransformerTest.scala
+++ b/features/src/test/scala/com/salesforce/op/stages/base/binary/BinaryTransformerTest.scala
@@ -43,7 +43,7 @@ class BinaryTransformerTest extends OpTransformerSpec[Real, BinaryTransformer[Re
   val (inputData, f1, f2) = TestFeatureBuilder(sample)
 
   val transformer = new BinaryLambdaTransformer[Real, RealNN, Real](
-    operationName = "bmi", transformFn = BinaryTransformerTest.fn
+    operationName = "bmi", transformFn = new BinaryTransformerTest.Fun
   ).setInput(f1, f2)
 
   val expectedResult = Seq(Real(Double.PositiveInfinity), Real(0.5), Real.empty)
@@ -51,5 +51,8 @@ class BinaryTransformerTest extends OpTransformerSpec[Real, BinaryTransformer[Re
 }
 
 object BinaryTransformerTest {
-  def fn: (Real, RealNN) => Real = (i1, i2) => new Real(for {v1 <- i1.value; v2 <- i2.value} yield v1 / (v2 * v2))
+
+  class Fun extends Function2[Real, RealNN, Real] with Serializable {
+    def apply(i1: Real, i2: RealNN): Real = new Real(for {v1 <- i1.value; v2 <- i2.value} yield v1 / (v2 * v2))
+  }
 }
diff --git a/features/src/test/scala/com/salesforce/op/stages/base/quaternary/QuaternaryTransformerTest.scala b/features/src/test/scala/com/salesforce/op/stages/base/quaternary/QuaternaryTransformerTest.scala
index 0e029e8d55..fbb789b3e9 100644
--- a/features/src/test/scala/com/salesforce/op/stages/base/quaternary/QuaternaryTransformerTest.scala
+++ b/features/src/test/scala/com/salesforce/op/stages/base/quaternary/QuaternaryTransformerTest.scala
@@ -49,7 +49,7 @@ class QuaternaryTransformerTest
   val (inputData, f1, f2, f3, f4) = TestFeatureBuilder(sample)
 
   val transformer = new QuaternaryLambdaTransformer[Real, Integral, Text, Binary, Real](
-    operationName = "quatro", transformFn = QuaternaryTransformerTest.fn
+    operationName = "quatro", transformFn = new QuaternaryTransformerTest.Fun
   ).setInput(f1, f2, f3, f4)
 
   val expectedResult = Seq(4.toReal, 6.toReal, 11.toReal)
@@ -57,7 +57,11 @@ class QuaternaryTransformerTest
 }
 
 object QuaternaryTransformerTest {
-  def fn: (Real, Integral, Text, Binary) => Real = (r, i, t, b) =>
-    (r.v.getOrElse(0.0) + i.toDouble.getOrElse(0.0) + b.toDouble.getOrElse(0.0) +
-      t.value.map(_.length.toDouble).getOrElse(0.0)).toReal
+
+  class Fun extends Function4[Real, Integral, Text, Binary, Real] with Serializable {
+    def apply(r: Real, i: Integral, t: Text, b: Binary): Real =
+      (r.v.getOrElse(0.0) + i.toDouble.getOrElse(0.0) + b.toDouble.getOrElse(0.0) +
+        t.value.map(_.length.toDouble).getOrElse(0.0)).toReal
+  }
+
 }
diff --git a/features/src/test/scala/com/salesforce/op/stages/base/sequence/BinarySequenceTransformerTest.scala b/features/src/test/scala/com/salesforce/op/stages/base/sequence/BinarySequenceTransformerTest.scala
index 6ec1bca0fc..73d59d6bec 100644
--- a/features/src/test/scala/com/salesforce/op/stages/base/sequence/BinarySequenceTransformerTest.scala
+++ b/features/src/test/scala/com/salesforce/op/stages/base/sequence/BinarySequenceTransformerTest.scala
@@ -50,7 +50,7 @@ class BinarySequenceTransformerTest
   val (inputData, f1, f2, f3) = TestFeatureBuilder(sample)
 
   val transformer = new BinarySequenceLambdaTransformer[Real, Text, MultiPickList](
-    operationName = "realToMultiPicklist", transformFn = Lambda.fn
+    operationName = "realToMultiPicklist", transformFn = new BinarySequenceTransformerTest.Fun
   ).setInput(f1, f2, f3)
 
   val expectedResult = Seq(
@@ -61,7 +61,11 @@ class BinarySequenceTransformerTest
   ).map(_.toMultiPickList)
 }
 
-object Lambda {
-  def fn: (Real, Seq[Text]) => MultiPickList =
-    (r, texts) => MultiPickList(texts.map(_.value.get).toSet + r.value.get.toString)
+object BinarySequenceTransformerTest {
+
+  class Fun extends Function2[Real, Seq[Text], MultiPickList] with Serializable {
+    def apply(r: Real, texts: Seq[Text]): MultiPickList =
+      MultiPickList(texts.map(_.value.get).toSet + r.value.get.toString)
+  }
+
 }
diff --git a/features/src/test/scala/com/salesforce/op/stages/base/sequence/SequenceTransformerTest.scala b/features/src/test/scala/com/salesforce/op/stages/base/sequence/SequenceTransformerTest.scala
index a03e3b1ec3..7dceafee1a 100644
--- a/features/src/test/scala/com/salesforce/op/stages/base/sequence/SequenceTransformerTest.scala
+++ b/features/src/test/scala/com/salesforce/op/stages/base/sequence/SequenceTransformerTest.scala
@@ -48,7 +48,7 @@ class SequenceTransformerTest extends OpTransformerSpec[MultiPickList, SequenceT
   val (inputData, f1, f2) = TestFeatureBuilder(sample)
 
   val transformer = new SequenceLambdaTransformer[Real, MultiPickList](
-    operationName = "realToMultiPicklist", transformFn = SequenceTransformerTest.fn
+    operationName = "realToMultiPicklist", transformFn = new SequenceTransformerTest.Fun
   ).setInput(f1, f2)
 
   val expectedResult = Seq(
@@ -61,5 +61,8 @@ class SequenceTransformerTest extends OpTransformerSpec[MultiPickList, SequenceT
 }
 
 object SequenceTransformerTest {
-  def fn: Seq[Real] => MultiPickList = value => MultiPickList(value.flatMap(_.v.map(_.toString)).toSet)
+
+  class Fun extends Function1[Seq[Real], MultiPickList] with Serializable {
+    def apply(value: Seq[Real]): MultiPickList = MultiPickList(value.flatMap(_.v.map(_.toString)).toSet)
+  }
 }
diff --git a/features/src/test/scala/com/salesforce/op/stages/base/ternary/TernaryTransformerTest.scala b/features/src/test/scala/com/salesforce/op/stages/base/ternary/TernaryTransformerTest.scala
index 26bdd38533..2e6e56e08d 100644
--- a/features/src/test/scala/com/salesforce/op/stages/base/ternary/TernaryTransformerTest.scala
+++ b/features/src/test/scala/com/salesforce/op/stages/base/ternary/TernaryTransformerTest.scala
@@ -48,14 +48,18 @@ class TernaryTransformerTest extends OpTransformerSpec[Real, TernaryTransformer[
   val (inputData, f1, f2, f3) = TestFeatureBuilder(sample)
 
   val transformer = new TernaryLambdaTransformer[Real, Integral, Binary, Real](
-    operationName = "trio", transformFn = Lambda.fn
+    operationName = "trio", transformFn = new TernaryTransformerTest.Fun
   ).setInput(f1, f2, f3)
 
   val expectedResult = Seq(1.toReal, 5.toReal, 4.toReal)
 
 }
 
-object Lambda {
-  def fn: (Real, Integral, Binary) => Real =
-    (r, i, b) => (r.v.getOrElse(0.0) + i.toDouble.getOrElse(0.0) + b.toDouble.getOrElse(0.0)).toReal
+object TernaryTransformerTest {
+
+  class Fun extends Function3[Real, Integral, Binary, Real] with Serializable {
+    def apply(r: Real, i: Integral, b: Binary): Real =
+      (r.v.getOrElse(0.0) + i.toDouble.getOrElse(0.0) + b.toDouble.getOrElse(0.0)).toReal
+  }
+
 }
diff --git a/features/src/test/scala/com/salesforce/op/stages/base/unary/UnaryTransformerTest.scala b/features/src/test/scala/com/salesforce/op/stages/base/unary/UnaryTransformerTest.scala
index d7cbbfcccc..a163c659b2 100644
--- a/features/src/test/scala/com/salesforce/op/stages/base/unary/UnaryTransformerTest.scala
+++ b/features/src/test/scala/com/salesforce/op/stages/base/unary/UnaryTransformerTest.scala
@@ -48,7 +48,7 @@ class UnaryTransformerTest extends OpTransformerSpec[Real, UnaryLambdaTransforme
    * [[OpTransformer]] instance to be tested
    */
   val transformer = new UnaryLambdaTransformer[Real, Real](
-    operationName = "unary", transformFn = UnaryTransformerTest.fn
+    operationName = "unary", transformFn = new UnaryTransformerTest.Fun
   ).setInput(f1)
 
   /**
@@ -59,5 +59,9 @@ class UnaryTransformerTest extends OpTransformerSpec[Real, UnaryLambdaTransforme
 }
 
 object UnaryTransformerTest {
-  def fn: Real => Real = r => r.v.map(_ * 2.0).toReal
+
+  class Fun extends Function1[Real, Real] with Serializable {
+    def apply(r: Real): Real = r.v.map(_ * 2.0).toReal
+  }
+
 }
diff --git a/readers/src/main/scala/com/salesforce/op/test/PassengerFeaturesTest.scala b/readers/src/main/scala/com/salesforce/op/test/PassengerFeaturesTest.scala
index 975bbf567a..ffd4b77398 100644
--- a/readers/src/main/scala/com/salesforce/op/test/PassengerFeaturesTest.scala
+++ b/readers/src/main/scala/com/salesforce/op/test/PassengerFeaturesTest.scala
@@ -34,24 +34,25 @@ import com.salesforce.op.aggregators.MaxReal
 import com.salesforce.op.features.types._
 import com.salesforce.op.features.{FeatureBuilder, OPFeature}
 import org.joda.time.Duration
-import PassengerFeaturesTestLambdas._
+import PassengerFeaturesTest._
 
 
 trait PassengerFeaturesTest {
-  val age = FeatureBuilder.Real[Passenger].extract(ageFn).aggregate(MaxReal).asPredictor
-  val gender = FeatureBuilder.MultiPickList[Passenger].extract(genderFn).asPredictor
-  val genderPL = FeatureBuilder.PickList[Passenger].extract(genderPLFn).asPredictor
-  val height = FeatureBuilder.RealNN[Passenger].extract(heightFn).window(Duration.millis(300)).asPredictor
-  val heightNoWindow = FeatureBuilder.Real[Passenger].extract(heightToReal).asPredictor
-  val weight = FeatureBuilder.Real[Passenger].extract(weightToReal).asPredictor
-  val description = FeatureBuilder.Text[Passenger].extract(descriptionFn).asPredictor
-  val boarded = FeatureBuilder.DateList[Passenger].extract(boardedToDL).asPredictor
-  val stringMap = FeatureBuilder.TextMap[Passenger].extract(stringMapFn).asPredictor
-  val numericMap = FeatureBuilder.RealMap[Passenger].extract(numericMapFn).asPredictor
-  val booleanMap = FeatureBuilder.BinaryMap[Passenger].extract(booleanMapFn).asPredictor
-  val survived = FeatureBuilder.Binary[Passenger].extract(survivedFn).asResponse
-  val boardedTime = FeatureBuilder.Date[Passenger].extract(boardedTimeFn).asPredictor
-  val boardedTimeAsDateTime = FeatureBuilder.DateTime[Passenger].extract(boardedDTFn).asPredictor
+  val age = FeatureBuilder.Real[Passenger].extract(new AgeExtract).aggregate(MaxReal).asPredictor
+  val gender = FeatureBuilder.MultiPickList[Passenger].extract(new GenderAsMultiPickListExtract).asPredictor
+  val genderPL = FeatureBuilder.PickList[Passenger].extract(new GenderAsPickListExtract).asPredictor
+  val height = FeatureBuilder.RealNN[Passenger].extract(new HeightToRealNNExtract)
+    .window(Duration.millis(300)).asPredictor
+  val heightNoWindow = FeatureBuilder.Real[Passenger].extract(new HeightToRealExtract).asPredictor
+  val weight = FeatureBuilder.Real[Passenger].extract(new WeightToRealExtract).asPredictor
+  val description = FeatureBuilder.Text[Passenger].extract(new DescriptionExtract).asPredictor
+  val boarded = FeatureBuilder.DateList[Passenger].extract(new BoardedToDateListExtract).asPredictor
+  val stringMap = FeatureBuilder.TextMap[Passenger].extract(new StringMapExtract).asPredictor
+  val numericMap = FeatureBuilder.RealMap[Passenger].extract(new NumericMapExtract).asPredictor
+  val booleanMap = FeatureBuilder.BinaryMap[Passenger].extract(new BooleanMapExtract).asPredictor
+  val survived = FeatureBuilder.Binary[Passenger].extract(new SurvivedExtract).asResponse
+  val boardedTime = FeatureBuilder.Date[Passenger].extract(new BoardedToDateExtract).asPredictor
+  val boardedTimeAsDateTime = FeatureBuilder.DateTime[Passenger].extract(new BoardedToDateTimeExtract).asPredictor
 
   val rawFeatures: Array[OPFeature] = Array(
     survived, age, gender, height, weight, description, boarded, stringMap, numericMap, booleanMap
@@ -59,19 +60,49 @@ trait PassengerFeaturesTest {
 
 }
 
-object PassengerFeaturesTestLambdas {
-  def genderFn: Passenger => MultiPickList = p => Set(p.getGender).toMultiPickList
-  def genderPLFn: Passenger => PickList = p => p.getGender.toPickList
-  def heightFn: Passenger => RealNN = p => Option(p.getHeight).map(_.toDouble).toRealNN(0.0)
-  def heightToReal: Passenger => Real = _.getHeight.toReal
-  def weightToReal: Passenger => Real = _.getWeight.toReal
-  def descriptionFn: Passenger => Text = _.getDescription.toText
-  def boardedToDL: Passenger => DateList = p => Seq(p.getBoarded.toLong).toDateList
-  def stringMapFn: Passenger => TextMap = p => p.getStringMap.toTextMap
-  def numericMapFn: Passenger => RealMap = p => p.getNumericMap.toRealMap
-  def booleanMapFn: Passenger => BinaryMap = p => p.getBooleanMap.toBinaryMap
-  def survivedFn: Passenger => Binary = p => Option(p.getSurvived).map(_ == 1).toBinary
-  def boardedTimeFn: Passenger => Date = _.getBoarded.toLong.toDate
-  def boardedDTFn: Passenger => DateTime = _.getBoarded.toLong.toDateTime
-  def ageFn: Passenger => Real = _.getAge.toReal
+object PassengerFeaturesTest {
+
+  class GenderAsMultiPickListExtract extends Function1[Passenger, MultiPickList] with Serializable {
+    def apply(p: Passenger): MultiPickList = Set(p.getGender).toMultiPickList
+  }
+  class GenderAsPickListExtract extends Function1[Passenger, PickList] with Serializable {
+    def apply(p: Passenger): PickList = p.getGender.toPickList
+  }
+  class HeightToRealNNExtract extends Function1[Passenger, RealNN] with Serializable {
+    def apply(p: Passenger): RealNN = Option(p.getHeight).map(_.toDouble).toRealNN(0.0)
+  }
+  class HeightToRealExtract extends Function1[Passenger, Real] with Serializable {
+    def apply(p: Passenger): Real = p.getHeight.toReal
+  }
+  class WeightToRealExtract extends Function1[Passenger, Real] with Serializable {
+    def apply(p: Passenger): Real = p.getWeight.toReal
+  }
+  class DescriptionExtract extends Function1[Passenger, Text] with Serializable {
+    def apply(p: Passenger): Text = p.getDescription.toText
+  }
+  class BoardedToDateListExtract extends Function1[Passenger, DateList] with Serializable {
+    def apply(p: Passenger): DateList = Seq(p.getBoarded.toLong).toDateList
+  }
+  class BoardedToDateExtract extends Function1[Passenger, Date] with Serializable {
+    def apply(p: Passenger): Date = p.getBoarded.toLong.toDate
+  }
+  class BoardedToDateTimeExtract extends Function1[Passenger, DateTime] with Serializable {
+    def apply(p: Passenger): DateTime = p.getBoarded.toLong.toDateTime
+  }
+  class SurvivedExtract extends Function1[Passenger, Binary] with Serializable {
+    def apply(p: Passenger): Binary = Option(p.getSurvived).map(_ == 1).toBinary
+  }
+  class StringMapExtract extends Function1[Passenger, TextMap] with Serializable {
+    def apply(p: Passenger): TextMap = p.getStringMap.toTextMap
+  }
+  class NumericMapExtract extends Function1[Passenger, RealMap] with Serializable {
+    def apply(p: Passenger): RealMap = p.getNumericMap.toRealMap
+  }
+  class BooleanMapExtract extends Function1[Passenger, BinaryMap] with Serializable {
+    def apply(p: Passenger): BinaryMap = p.getBooleanMap.toBinaryMap
+  }
+  class AgeExtract extends Function1[Passenger, Real] with Serializable {
+    def apply(p: Passenger): Real = p.getAge.toReal
+  }
+
 }