diff --git a/src/main/scala/com/audienceproject/crossbow/DataFrame.scala b/src/main/scala/com/audienceproject/crossbow/DataFrame.scala
index 171e7ac..0dfcdb6 100644
--- a/src/main/scala/com/audienceproject/crossbow/DataFrame.scala
+++ b/src/main/scala/com/audienceproject/crossbow/DataFrame.scala
@@ -39,7 +39,7 @@ class DataFrame private(private val columnData: Vector[Array[_]],
    * @return new DataFrame
    */
   def apply(columnNames: String*): DataFrame = {
-    val colExprs = columnNames.map(Expr.Column)
+    val colExprs = columnNames.map(Expr.Cell)
     select(colExprs: _*)
   }
 
@@ -100,8 +100,8 @@ class DataFrame private(private val columnData: Vector[Array[_]],
    */
   def select(exprs: Expr*): DataFrame = {
     val (colData, colSchemas) = exprs.zipWithIndex.map({
-      case (Expr.Named(newName, Expr.Column(colName)), _) => (getColumnData(colName), schema.get(colName).renamed(newName))
-      case (Expr.Column(colName), _) => (getColumnData(colName), schema.get(colName))
+      case (Expr.Named(newName, Expr.Cell(colName)), _) => (getColumnData(colName), schema.get(colName).renamed(newName))
+      case (Expr.Cell(colName), _) => (getColumnData(colName), schema.get(colName))
       case (expr, i) =>
         val eval = expr.compile(this)
         val newColSchema = expr match {
@@ -225,7 +225,7 @@ class DataFrame private(private val columnData: Vector[Array[_]],
 
   private[crossbow] def slice(indices: IndexedSeq[Int]): DataFrame = {
     val newData = schema.columns.map(col => {
-      val eval = Expr.Column(col.name).compile(this)
+      val eval = Expr.Cell(col.name).compile(this)
       sliceColumn(eval, indices)
     })
     new DataFrame(newData.toVector, schema)
diff --git a/src/main/scala/com/audienceproject/crossbow/Implicits.scala b/src/main/scala/com/audienceproject/crossbow/Implicits.scala
index faaf570..c998d5b 100644
--- a/src/main/scala/com/audienceproject/crossbow/Implicits.scala
+++ b/src/main/scala/com/audienceproject/crossbow/Implicits.scala
@@ -9,7 +9,7 @@ object Implicits {
 
   // Column expression.
   implicit class ColumnByName(val sc: StringContext) extends AnyVal {
-    def $(args: Any*): Expr = Expr.Column(sc.s(args: _*))
+    def $(args: Any*): Expr = Expr.Cell(sc.s(args: _*))
   }
 
   // Literal value.
diff --git a/src/main/scala/com/audienceproject/crossbow/algorithms/GroupBy.scala b/src/main/scala/com/audienceproject/crossbow/algorithms/GroupBy.scala
index 98d93e2..46bda98 100644
--- a/src/main/scala/com/audienceproject/crossbow/algorithms/GroupBy.scala
+++ b/src/main/scala/com/audienceproject/crossbow/algorithms/GroupBy.scala
@@ -14,8 +14,8 @@ private[crossbow] object GroupBy {
     val selectExprs = aggExprs.map(Traversal.transform(_, {
       case agg: Aggregator =>
         aggregators += agg
-        Expr.Column(s"_res${aggregators.size}")
-      case col: Expr.Column => throw new AggregationException(col)
+        Expr.Cell(s"_res${aggregators.size}")
+      case col: Expr.Cell => throw new AggregationException(col)
     }))
 
     val keyEvals = keyExprs.map(_.compile(dataFrame)).toList
@@ -34,14 +34,14 @@ private[crossbow] object GroupBy {
 
     val keyNames = keyExprs.zipWithIndex.map({
       case (Expr.Named(name, _), _) => name
-      case (Expr.Column(name), _) => name
+      case (Expr.Cell(name), _) => name
       case (_, i) => s"_key$i"
     })
     val keySchemaCols = keyNames.zip(keyEvals).map({ case (name, eval) => Column(name, eval.typeOf) }).toList
     val dataSchemaCols = reducers.zipWithIndex.map({ case (reducer, i) => Column(s"_res${i + 1}", reducer.typeOf) })
 
     val temp = DataFrame.fromColumns(newKeyCols ++ newDataCols, Schema(keySchemaCols ++ dataSchemaCols))
-    temp.select(keySchemaCols.map(c => Expr.Column(c.name)) ++ selectExprs: _*)
+    temp.select(keySchemaCols.map(c => Expr.Cell(c.name)) ++ selectExprs: _*)
   }
 
 }
diff --git a/src/main/scala/com/audienceproject/crossbow/algorithms/SortMergeJoin.scala b/src/main/scala/com/audienceproject/crossbow/algorithms/SortMergeJoin.scala
index 2fb444e..dfd06be 100644
--- a/src/main/scala/com/audienceproject/crossbow/algorithms/SortMergeJoin.scala
+++ b/src/main/scala/com/audienceproject/crossbow/algorithms/SortMergeJoin.scala
@@ -17,8 +17,8 @@ private[crossbow] object SortMergeJoin {
 
     val ordering = Order.getOrdering(internalType)
 
-    val leftSorted = left.addColumn(joinExpr as joinColName).sortBy(Expr.Column(joinColName))
-    val rightSorted = right.addColumn(joinExpr as joinColName).sortBy(Expr.Column(joinColName))
+    val leftSorted = left.addColumn(joinExpr as joinColName).sortBy(Expr.Cell(joinColName))
+    val rightSorted = right.addColumn(joinExpr as joinColName).sortBy(Expr.Cell(joinColName))
 
     val leftKey = leftSorted(joinColName).as[Any]
     val rightKey = rightSorted(joinColName).as[Any]
diff --git a/src/main/scala/com/audienceproject/crossbow/expr/BinaryExpr.scala b/src/main/scala/com/audienceproject/crossbow/expr/BinaryExpr.scala
index 21b81a0..65ab44f 100644
--- a/src/main/scala/com/audienceproject/crossbow/expr/BinaryExpr.scala
+++ b/src/main/scala/com/audienceproject/crossbow/expr/BinaryExpr.scala
@@ -20,8 +20,8 @@ protected abstract class BinaryExpr(private val lhs: Expr, private val rhs: Expr
 
 private[crossbow] object BinaryExpr {
 
-  case class BinaryOp[T, U, V: ru.TypeTag](lhs: Specialized[T], rhs: Specialized[U],
-                                           op: (T, U) => V)
+  private[BinaryExpr] case class BinaryOp[T, U, V: ru.TypeTag](lhs: Specialized[T], rhs: Specialized[U],
+                                                               op: (T, U) => V)
     extends Specialized[V] {
     override def apply(i: Int): V = op(lhs(i), rhs(i))
   }
diff --git a/src/main/scala/com/audienceproject/crossbow/expr/Expr.scala b/src/main/scala/com/audienceproject/crossbow/expr/Expr.scala
index d67e9b8..43d6acc 100644
--- a/src/main/scala/com/audienceproject/crossbow/expr/Expr.scala
+++ b/src/main/scala/com/audienceproject/crossbow/expr/Expr.scala
@@ -13,7 +13,7 @@ private[crossbow] object Expr {
     override private[crossbow] def compile(context: DataFrame) = expr.compile(context)
   }
 
-  case class Column(columnName: String) extends Expr {
+  case class Cell(columnName: String) extends Expr {
     override private[crossbow] def compile(context: DataFrame) = {
       val columnType = context.schema.get(columnName).columnType
       columnType match {
diff --git a/src/main/scala/com/audienceproject/crossbow/expr/UnaryExpr.scala b/src/main/scala/com/audienceproject/crossbow/expr/UnaryExpr.scala
index edf616d..33969cf 100644
--- a/src/main/scala/com/audienceproject/crossbow/expr/UnaryExpr.scala
+++ b/src/main/scala/com/audienceproject/crossbow/expr/UnaryExpr.scala
@@ -18,7 +18,7 @@ protected abstract class UnaryExpr(private val expr: Expr) extends Expr {
 
 private[crossbow] object UnaryExpr {
 
-  case class UnaryOp[T, U: ru.TypeTag](operand: Specialized[T], op: T => U)
+  private[UnaryExpr] case class UnaryOp[T, U: ru.TypeTag](operand: Specialized[T], op: T => U)
     extends Specialized[U] {
     override def apply(i: Int): U = op(operand(i))
   }
diff --git a/src/test/scala/com/audienceproject/crossbow/algorithms/TraversalTest.scala b/src/test/scala/com/audienceproject/crossbow/algorithms/TraversalTest.scala
index 07224af..83f7453 100644
--- a/src/test/scala/com/audienceproject/crossbow/algorithms/TraversalTest.scala
+++ b/src/test/scala/com/audienceproject/crossbow/algorithms/TraversalTest.scala
@@ -12,7 +12,7 @@ class TraversalTest extends AnyFunSuite {
 
   test("Transform expression tree") {
     val transformedExpr = Traversal.transform(aggExpr, {
-      case _: Aggregator => Expr.Column("42")
+      case _: Aggregator => Expr.Cell("42")
     })
     val expected = $"42" + $"42" / 2 * $"42"
     assert(transformedExpr == expected)
@@ -22,7 +22,7 @@ class TraversalTest extends AnyFunSuite {
     val list = mutable.ListBuffer.empty[Expr]
     val transformedExpr = Traversal.transform(aggExpr, {
       case _: Aggregator =>
-        val newCol = Expr.Column(s"_${list.size}")
+        val newCol = Expr.Cell(s"_${list.size}")
         list += newCol
         newCol
     })
diff --git a/src/test/scala/com/audienceproject/crossbow/core/TypedViewTest.scala b/src/test/scala/com/audienceproject/crossbow/core/TypedViewTest.scala
new file mode 100644
index 0000000..ee4a17a
--- /dev/null
+++ b/src/test/scala/com/audienceproject/crossbow/core/TypedViewTest.scala
@@ -0,0 +1,23 @@
+package com.audienceproject.crossbow.core
+
+import com.audienceproject.crossbow.DataFrame
+import com.audienceproject.crossbow.Implicits._
+import org.scalatest.funsuite.AnyFunSuite
+
+class TypedViewTest extends AnyFunSuite {
+
+  private val df = DataFrame.fromSeq(Seq(("a", 1), ("b", 2), ("c", 3)))
+
+  test("Cast DataFrame to TypedView of single type") {
+    val result = df.select($"_0").as[String].toSeq
+    val expected = Seq("a", "b", "c")
+    assert(result == expected)
+  }
+
+  test("Cast DataFrame to TypedView of tuple") {
+    val result = df.as[(String, Int)].toSeq
+    val expected = Seq(("a", 1), ("b", 2), ("c", 3))
+    assert(result == expected)
+  }
+
+}
diff --git a/wercker.yml b/wercker.yml
index e3894f6..a140b34 100644
--- a/wercker.yml
+++ b/wercker.yml
@@ -11,7 +11,7 @@ build:
         code: sbt clean +compile
     - script:
         name: Test
-        code: sbt +test
+        code: sbt test
     - script:
         name: Clean again
         code: sbt clean