diff --git a/core/src/main/scala/doric/sem/JoinOps.scala b/core/src/main/scala/doric/sem/JoinOps.scala
index 61a012137..b30e4ca2d 100644
--- a/core/src/main/scala/doric/sem/JoinOps.scala
+++ b/core/src/main/scala/doric/sem/JoinOps.scala
@@ -5,7 +5,7 @@ import doric.{DoricColumn, DoricJoinColumn}
 
 import org.apache.spark.sql.{DataFrame, Dataset}
 
-private[sem] trait JoinOps {
+protected trait JoinOps {
   implicit class DataframeJoinSyntax[A](df: Dataset[A]) {
 
     /**
diff --git a/core/src/main/scala/doric/syntax/AggregationColumns.scala b/core/src/main/scala/doric/syntax/AggregationColumns.scala
index 0011146e8..6dc968b10 100644
--- a/core/src/main/scala/doric/syntax/AggregationColumns.scala
+++ b/core/src/main/scala/doric/syntax/AggregationColumns.scala
@@ -8,7 +8,7 @@ import doric.Doric
 import org.apache.spark.sql.{Column, functions => f}
 import org.apache.spark.sql.catalyst.expressions.aggregate.Sum
 
-private[syntax] trait AggregationColumns {
+protected trait AggregationColumns {
 
   /**
     * Aggregate function: returns the sum of all values in the expression.
diff --git a/core/src/main/scala/doric/syntax/ArrayColumns.scala b/core/src/main/scala/doric/syntax/ArrayColumns.scala
index eaf9bd17a..c93c9a41f 100644
--- a/core/src/main/scala/doric/syntax/ArrayColumns.scala
+++ b/core/src/main/scala/doric/syntax/ArrayColumns.scala
@@ -33,7 +33,7 @@ protected final case class Zipper[T1, T2, F[_]: CollectionType](
   }
 }
 
-private[syntax] trait ArrayColumns {
+protected trait ArrayColumns {
 
   /**
     * Concatenates multiple array columns together into a single column.
@@ -525,7 +525,8 @@ private[syntax] trait ArrayColumns {
       * @note
       * if `start` == 0 an exception will be thrown
       * @group Array Type
-      * @see [[org.apache.spark.sql.functions.slice(x:org\.apache\.spark\.sql\.Column,start:org\.apache\.spark\.sql\.Column,length* org.apache.spark.sql.functions.slice]]
+      * @see org.apache.spark.sql.functions.slice
+      * @todo scaladoc link (issue #135)
       */
     def slice(start: IntegerColumn, length: IntegerColumn): ArrayColumn[T] =
       (col.elem, start.elem, length.elem)
diff --git a/core/src/main/scala/doric/syntax/BinaryColumns.scala b/core/src/main/scala/doric/syntax/BinaryColumns.scala
index f50842db2..65184942b 100644
--- a/core/src/main/scala/doric/syntax/BinaryColumns.scala
+++ b/core/src/main/scala/doric/syntax/BinaryColumns.scala
@@ -6,7 +6,7 @@ import doric.types.{BinaryType, SparkType}
 
 import org.apache.spark.sql.{functions => f}
 
-private[syntax] trait BinaryColumns {
+protected trait BinaryColumns {
 
   /**
     * Concatenates multiple binary columns together into a single column.
diff --git a/core/src/main/scala/doric/syntax/BooleanColumns.scala b/core/src/main/scala/doric/syntax/BooleanColumns.scala
index faa20e8f1..19c7154ec 100644
--- a/core/src/main/scala/doric/syntax/BooleanColumns.scala
+++ b/core/src/main/scala/doric/syntax/BooleanColumns.scala
@@ -5,7 +5,7 @@ import doric.DoricColumn.sparkFunction
 
 import org.apache.spark.sql.{functions => f}
 
-private[syntax] trait BooleanColumns {
+protected trait BooleanColumns {
 
   /**
     * Inversion of boolean expression, i.e. NOT.
diff --git a/core/src/main/scala/doric/syntax/CommonColumns.scala b/core/src/main/scala/doric/syntax/CommonColumns.scala
index 7a42d56a6..bea3516af 100644
--- a/core/src/main/scala/doric/syntax/CommonColumns.scala
+++ b/core/src/main/scala/doric/syntax/CommonColumns.scala
@@ -8,7 +8,7 @@ import doric.types.{Casting, SparkType, UnsafeCasting}
 import org.apache.spark.sql.{Column, functions => f}
 import org.apache.spark.sql.catalyst.expressions.ArrayRepeat
 
-private[syntax] trait CommonColumns extends ColGetters[NamedDoricColumn] {
+protected trait CommonColumns extends ColGetters[NamedDoricColumn] {
 
   /**
     * Returns the first column that is not null, or null if all inputs are null.
diff --git a/core/src/main/scala/doric/syntax/ControlStructures.scala b/core/src/main/scala/doric/syntax/ControlStructures.scala
index 9e20a90dc..5aa25e42c 100644
--- a/core/src/main/scala/doric/syntax/ControlStructures.scala
+++ b/core/src/main/scala/doric/syntax/ControlStructures.scala
@@ -1,7 +1,7 @@
 package doric
 package syntax
 
-private[syntax] trait ControlStructures {
+protected trait ControlStructures {
 
   /**
     * Initialize a when builder
diff --git a/core/src/main/scala/doric/syntax/DStructs.scala b/core/src/main/scala/doric/syntax/DStructs.scala
index 994b90df4..f7a8c0472 100644
--- a/core/src/main/scala/doric/syntax/DStructs.scala
+++ b/core/src/main/scala/doric/syntax/DStructs.scala
@@ -14,7 +14,7 @@ import org.apache.spark.sql.functions.{struct => sparkStruct}
 import shapeless.labelled.FieldType
 import shapeless.{::, HList, LabelledGeneric, Witness}
 
-private[syntax] trait DStructs {
+protected trait DStructs {
 
   /**
     * Creates a struct with the columns
diff --git a/core/src/main/scala/doric/syntax/DateColumns.scala b/core/src/main/scala/doric/syntax/DateColumns.scala
index 368f89403..1c2a2fad2 100644
--- a/core/src/main/scala/doric/syntax/DateColumns.scala
+++ b/core/src/main/scala/doric/syntax/DateColumns.scala
@@ -9,7 +9,7 @@ import java.sql.Date
 import org.apache.spark.sql.{Column, functions => f}
 import org.apache.spark.sql.catalyst.expressions.{AddMonths, CurrentDate, DateAdd, DateFormatClass, DateSub, MonthsBetween, NextDay, TruncDate, TruncTimestamp}
 
-private[syntax] trait DateColumns {
+protected trait DateColumns {
 
   /**
     * Returns the current date at the start of query evaluation as a date column.
diff --git a/core/src/main/scala/doric/syntax/LiteralConversions.scala b/core/src/main/scala/doric/syntax/LiteralConversions.scala
index 1908626ce..a05e9fe77 100644
--- a/core/src/main/scala/doric/syntax/LiteralConversions.scala
+++ b/core/src/main/scala/doric/syntax/LiteralConversions.scala
@@ -5,7 +5,7 @@ import doric.sem.Location
 import doric.types.SparkType.Primitive
 import doric.types.{LiteralSparkType, SparkType}
 
-private[syntax] trait LiteralConversions {
+protected trait LiteralConversions {
 
   /**
     * Creates a literal with the provided value.
diff --git a/core/src/main/scala/doric/syntax/MapColumns.scala b/core/src/main/scala/doric/syntax/MapColumns.scala
index ad27e9c98..1dc24433e 100644
--- a/core/src/main/scala/doric/syntax/MapColumns.scala
+++ b/core/src/main/scala/doric/syntax/MapColumns.scala
@@ -6,7 +6,7 @@ import cats.implicits._
 import org.apache.spark.sql.{Column, functions => f}
 import org.apache.spark.sql.functions.{map_keys, map_values}
 
-private[syntax] trait MapColumns {
+protected trait MapColumns {
 
   /**
     * Returns the union of all the given maps.
diff --git a/core/src/main/scala/doric/syntax/NumericColumns.scala b/core/src/main/scala/doric/syntax/NumericColumns.scala
index bf00e179f..5ddf5e4b2 100644
--- a/core/src/main/scala/doric/syntax/NumericColumns.scala
+++ b/core/src/main/scala/doric/syntax/NumericColumns.scala
@@ -7,7 +7,7 @@ import doric.types.{CollectionType, NumericType}
 import org.apache.spark.sql.catalyst.expressions.{BRound, FormatNumber, FromUnixTime, Rand, Randn, Round, UnaryMinus}
 import org.apache.spark.sql.{Column, functions => f}
 
-private[syntax] trait NumericColumns {
+protected trait NumericColumns {
 
   /**
     * Returns the current Unix timestamp (in seconds) as a long.
diff --git a/core/src/main/scala/doric/syntax/StringColumns.scala b/core/src/main/scala/doric/syntax/StringColumns.scala
index 3921112e1..478e0d02b 100644
--- a/core/src/main/scala/doric/syntax/StringColumns.scala
+++ b/core/src/main/scala/doric/syntax/StringColumns.scala
@@ -6,7 +6,7 @@ import cats.implicits._
 import org.apache.spark.sql.{Column, functions => f}
 import org.apache.spark.sql.catalyst.expressions._
 
-private[syntax] trait StringColumns {
+protected trait StringColumns {
 
   /**
     * Concatenate string columns to form a single one
diff --git a/core/src/main/scala/doric/syntax/TimestampColumns.scala b/core/src/main/scala/doric/syntax/TimestampColumns.scala
index bb0d87550..bcf04935c 100644
--- a/core/src/main/scala/doric/syntax/TimestampColumns.scala
+++ b/core/src/main/scala/doric/syntax/TimestampColumns.scala
@@ -7,7 +7,7 @@ import doric.types.{SparkType, TimestampType}
 import org.apache.spark.sql.{Column, functions => f}
 import org.apache.spark.sql.catalyst.expressions.{FromUTCTimestamp, ToUTCTimestamp}
 
-private[syntax] trait TimestampColumns {
+protected trait TimestampColumns {
 
   /**
     * Returns the current timestamp at the start of query evaluation as a timestamp column.
diff --git a/core/src/main/scala/doric/syntax/package.scala b/core/src/main/scala/doric/syntax/package.scala
index b7398689f..82067a96e 100644
--- a/core/src/main/scala/doric/syntax/package.scala
+++ b/core/src/main/scala/doric/syntax/package.scala
@@ -20,7 +20,7 @@ package object syntax {
     * @tparam K type of "key" doric column to perform the search
     * @tparam V type of "value" doric column result
     */
-  @inline private[syntax] def elementAtAbstract[T, K, V](
+  @inline def elementAtAbstract[T, K, V](
       dc: DoricColumn[T],
       key: DoricColumn[K]
   ): DoricColumn[V] = {
@@ -39,7 +39,7 @@ package object syntax {
     * @param dc doric column to be reversed
     * @tparam T type of doric column (string or array)
     */
-  @inline private[syntax] def reverseAbstract[T](
+  @inline def reverseAbstract[T](
       dc: DoricColumn[T]
   ): DoricColumn[T] =
     dc.elem.map(f.reverse).toDC
diff --git a/core/src/main/spark_2.4_3.0_3.1/scala/doric/syntax/BinaryColumns30_31.scala b/core/src/main/spark_2.4_3.0_3.1/scala/doric/syntax/BinaryColumns30_31.scala
index 31c996533..530c222d3 100644
--- a/core/src/main/spark_2.4_3.0_3.1/scala/doric/syntax/BinaryColumns30_31.scala
+++ b/core/src/main/spark_2.4_3.0_3.1/scala/doric/syntax/BinaryColumns30_31.scala
@@ -7,7 +7,7 @@ import doric.types.{BinaryType, SparkType}
 import org.apache.spark.sql.catalyst.expressions.Decode
 import org.apache.spark.sql.Column
 
-private[syntax] trait BinaryColumns30_31 {
+protected trait BinaryColumns30_31 {
 
   implicit class BinaryOperationsSyntax30_31[T: BinaryType: SparkType](
       column: DoricColumn[T]
diff --git a/core/src/main/spark_2.4_3.0_3.1/scala/doric/syntax/NumericColumns2_31.scala b/core/src/main/spark_2.4_3.0_3.1/scala/doric/syntax/NumericColumns2_31.scala
index 64b97cb5e..9868bd658 100644
--- a/core/src/main/spark_2.4_3.0_3.1/scala/doric/syntax/NumericColumns2_31.scala
+++ b/core/src/main/spark_2.4_3.0_3.1/scala/doric/syntax/NumericColumns2_31.scala
@@ -6,7 +6,7 @@ import org.apache.spark.sql.Column
 import org.apache.spark.sql.{functions => f}
 import org.apache.spark.sql.catalyst.expressions.{ShiftLeft, ShiftRight, ShiftRightUnsigned}
 
-private[syntax] trait NumericColumns2_31 {
+protected trait NumericColumns2_31 {
 
   /**
     * INTEGRAL OPERATIONS
diff --git a/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/AggregationColumns31.scala b/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/AggregationColumns31.scala
index f1dc6e724..bf2411464 100644
--- a/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/AggregationColumns31.scala
+++ b/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/AggregationColumns31.scala
@@ -5,7 +5,7 @@ import doric.types.DoubleC
 
 import org.apache.spark.sql.{functions => f}
 
-private[syntax] trait AggregationColumns31 {
+protected trait AggregationColumns31 {
 
   /**
     * Aggregate function: returns the approximate `percentile` of the numeric column `col` which
diff --git a/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/BooleanColumns31.scala b/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/BooleanColumns31.scala
index abfd30f4d..a19802d28 100644
--- a/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/BooleanColumns31.scala
+++ b/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/BooleanColumns31.scala
@@ -5,7 +5,7 @@ import cats.implicits._
 
 import org.apache.spark.sql.{functions => f}
 
-private[syntax] trait BooleanColumns31 {
+protected trait BooleanColumns31 {
 
   /**
     * @group Boolean Type
diff --git a/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/NumericColumns31.scala b/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/NumericColumns31.scala
index 5749691d6..1f458e31c 100644
--- a/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/NumericColumns31.scala
+++ b/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/NumericColumns31.scala
@@ -4,7 +4,7 @@ package syntax
 import doric.types.NumericType
 import org.apache.spark.sql.{functions => f}
 
-private[syntax] trait NumericColumns31 {
+protected trait NumericColumns31 {
   implicit class NumericOperationsSyntax31[T: NumericType](
       column: DoricColumn[T]
   ) {
diff --git a/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/StringColumns31.scala b/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/StringColumns31.scala
index 5917f59dc..4968680b1 100644
--- a/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/StringColumns31.scala
+++ b/core/src/main/spark_3.1_3.2_3.3/scala/doric/syntax/StringColumns31.scala
@@ -4,7 +4,7 @@ package syntax
 import doric.sem.Location
 import org.apache.spark.sql.{functions => f}
 
-private[syntax] trait StringColumns31 {
+protected trait StringColumns31 {
 
   /**
     * Throws an exception with the provided error message.
diff --git a/core/src/main/spark_3.2_3.3/scala/doric/syntax/BinaryColumns32.scala b/core/src/main/spark_3.2_3.3/scala/doric/syntax/BinaryColumns32.scala
index 4b3231a8e..4e785dc08 100644
--- a/core/src/main/spark_3.2_3.3/scala/doric/syntax/BinaryColumns32.scala
+++ b/core/src/main/spark_3.2_3.3/scala/doric/syntax/BinaryColumns32.scala
@@ -7,7 +7,7 @@ import doric.types.{BinaryType, SparkType}
 import org.apache.spark.sql.Column
 import org.apache.spark.sql.catalyst.expressions.StringDecode
 
-private[syntax] trait BinaryColumns32 {
+protected trait BinaryColumns32 {
 
   implicit class BinaryOperationsSyntax32[T: BinaryType: SparkType](
       column: DoricColumn[T]
diff --git a/core/src/main/spark_3.2_3.3/scala/doric/syntax/NumericColumns32.scala b/core/src/main/spark_3.2_3.3/scala/doric/syntax/NumericColumns32.scala
index eb6504e6e..2b25dbe23 100644
--- a/core/src/main/spark_3.2_3.3/scala/doric/syntax/NumericColumns32.scala
+++ b/core/src/main/spark_3.2_3.3/scala/doric/syntax/NumericColumns32.scala
@@ -6,7 +6,7 @@ import org.apache.spark.sql.Column
 import org.apache.spark.sql.{functions => f}
 import org.apache.spark.sql.catalyst.expressions.{ShiftLeft, ShiftRight, ShiftRightUnsigned}
 
-private[syntax] trait NumericColumns32 {
+protected trait NumericColumns32 {
 
   /**
     * INTEGRAL OPERATIONS