diff --git a/gtsam/discrete/DecisionTreeFactor.h b/gtsam/discrete/DecisionTreeFactor.h
index 9a3cde96d..8f3dd85a6 100644
--- a/gtsam/discrete/DecisionTreeFactor.h
+++ b/gtsam/discrete/DecisionTreeFactor.h
@@ -130,14 +130,9 @@ namespace gtsam {
     /// @name Standard Interface
     /// @{
 
-    /// Calculate probability for given values `x`, 
+    /// Calculate probability for given values, 
     /// is just look up in AlgebraicDecisionTree.
-    double evaluate(const Assignment<Key>& values) const  {
-      return ADT::operator()(values);
-    }
-
-    /// Evaluate probability distribution, sugar.
-    double operator()(const DiscreteValues& values) const override {
+    double operator()(const Assignment<Key>& values) const override {
       return ADT::operator()(values);
     }
 
diff --git a/gtsam/discrete/DiscreteFactor.h b/gtsam/discrete/DiscreteFactor.h
index 19af5bd13..5bc3c463f 100644
--- a/gtsam/discrete/DiscreteFactor.h
+++ b/gtsam/discrete/DiscreteFactor.h
@@ -92,8 +92,21 @@ class GTSAM_EXPORT DiscreteFactor : public Factor {
 
   size_t cardinality(Key j) const { return cardinalities_.at(j); }
 
+  /**
+   * @brief Calculate probability for given values.
+   * Calls specialized evaluation under the hood.
+   *
+   * Note: Uses Assignment<Key> as it is the base class of DiscreteValues.
+   *
+   * @param values Discrete assignment.
+   * @return double
+   */
+  double evaluate(const Assignment<Key>& values) const {
+    return operator()(values);
+  }
+
   /// Find value for given assignment of values to variables
-  virtual double operator()(const DiscreteValues&) const = 0;
+  virtual double operator()(const Assignment<Key>& values) const = 0;
 
   /// Error is just -log(value)
   virtual double error(const DiscreteValues& values) const;
diff --git a/gtsam/discrete/TableFactor.cpp b/gtsam/discrete/TableFactor.cpp
index f4e023a4d..32cba84ed 100644
--- a/gtsam/discrete/TableFactor.cpp
+++ b/gtsam/discrete/TableFactor.cpp
@@ -133,7 +133,7 @@ bool TableFactor::equals(const DiscreteFactor& other, double tol) const {
 }
 
 /* ************************************************************************ */
-double TableFactor::operator()(const DiscreteValues& values) const {
+double TableFactor::operator()(const Assignment<Key>& values) const {
   // a b c d => D * (C * (B * (a) + b) + c) + d
   uint64_t idx = 0, card = 1;
   for (auto it = sorted_dkeys_.rbegin(); it != sorted_dkeys_.rend(); ++it) {
@@ -180,6 +180,7 @@ DecisionTreeFactor TableFactor::toDecisionTreeFactor() const {
   for (auto i = 0; i < sparse_table_.size(); i++) {
     table.push_back(sparse_table_.coeff(i));
   }
+  // NOTE(Varun): This constructor is really expensive!!
   DecisionTreeFactor f(dkeys, table);
   return f;
 }
diff --git a/gtsam/discrete/TableFactor.h b/gtsam/discrete/TableFactor.h
index 7015353e1..53495d078 100644
--- a/gtsam/discrete/TableFactor.h
+++ b/gtsam/discrete/TableFactor.h
@@ -155,14 +155,8 @@ class GTSAM_EXPORT TableFactor : public DiscreteFactor {
   // /// @name Standard Interface
   // /// @{
 
-  /// Calculate probability for given values `x`,
-  /// is just look up in TableFactor.
-  double evaluate(const DiscreteValues& values) const {
-    return operator()(values);
-  }
-
-  /// Evaluate probability distribution, sugar.
-  double operator()(const DiscreteValues& values) const override;
+  /// Evaluate probability distribution, is just look up in TableFactor.
+  double operator()(const Assignment<Key>& values) const override;
 
   /// Calculate error for DiscreteValues `x`, is -log(probability).
   double error(const DiscreteValues& values) const override;
diff --git a/gtsam_unstable/discrete/AllDiff.cpp b/gtsam_unstable/discrete/AllDiff.cpp
index 2bd9e6dfd..a450605b3 100644
--- a/gtsam_unstable/discrete/AllDiff.cpp
+++ b/gtsam_unstable/discrete/AllDiff.cpp
@@ -26,7 +26,7 @@ void AllDiff::print(const std::string& s, const KeyFormatter& formatter) const {
 }
 
 /* ************************************************************************* */
-double AllDiff::operator()(const DiscreteValues& values) const {
+double AllDiff::operator()(const Assignment<Key>& values) const {
   std::set<size_t> taken;  // record values taken by keys
   for (Key dkey : keys_) {
     size_t value = values.at(dkey);      // get the value for that key
diff --git a/gtsam_unstable/discrete/AllDiff.h b/gtsam_unstable/discrete/AllDiff.h
index d7a63eae0..6fe43568e 100644
--- a/gtsam_unstable/discrete/AllDiff.h
+++ b/gtsam_unstable/discrete/AllDiff.h
@@ -45,7 +45,7 @@ class GTSAM_UNSTABLE_EXPORT AllDiff : public Constraint {
   }
 
   /// Calculate value = expensive !
-  double operator()(const DiscreteValues& values) const override;
+  double operator()(const Assignment<Key>& values) const override;
 
   /// Convert into a decisiontree, can be *very* expensive !
   DecisionTreeFactor toDecisionTreeFactor() const override;
diff --git a/gtsam_unstable/discrete/BinaryAllDiff.h b/gtsam_unstable/discrete/BinaryAllDiff.h
index 18b335092..a55865c77 100644
--- a/gtsam_unstable/discrete/BinaryAllDiff.h
+++ b/gtsam_unstable/discrete/BinaryAllDiff.h
@@ -47,7 +47,7 @@ class BinaryAllDiff : public Constraint {
   }
 
   /// Calculate value
-  double operator()(const DiscreteValues& values) const override {
+  double operator()(const Assignment<Key>& values) const override {
     return (double)(values.at(keys_[0]) != values.at(keys_[1]));
   }
 
diff --git a/gtsam_unstable/discrete/Domain.cpp b/gtsam_unstable/discrete/Domain.cpp
index bbbc87667..752228c18 100644
--- a/gtsam_unstable/discrete/Domain.cpp
+++ b/gtsam_unstable/discrete/Domain.cpp
@@ -30,7 +30,7 @@ string Domain::base1Str() const {
 }
 
 /* ************************************************************************* */
-double Domain::operator()(const DiscreteValues& values) const {
+double Domain::operator()(const Assignment<Key>& values) const {
   return contains(values.at(key()));
 }
 
diff --git a/gtsam_unstable/discrete/Domain.h b/gtsam_unstable/discrete/Domain.h
index 7f7b717c2..13249d733 100644
--- a/gtsam_unstable/discrete/Domain.h
+++ b/gtsam_unstable/discrete/Domain.h
@@ -82,7 +82,7 @@ class GTSAM_UNSTABLE_EXPORT Domain : public Constraint {
   bool contains(size_t value) const { return values_.count(value) > 0; }
 
   /// Calculate value
-  double operator()(const DiscreteValues& values) const override;
+  double operator()(const Assignment<Key>& values) const override;
 
   /// Convert into a decisiontree
   DecisionTreeFactor toDecisionTreeFactor() const override;
diff --git a/gtsam_unstable/discrete/SingleValue.cpp b/gtsam_unstable/discrete/SingleValue.cpp
index 6b78f38f5..9762aec0f 100644
--- a/gtsam_unstable/discrete/SingleValue.cpp
+++ b/gtsam_unstable/discrete/SingleValue.cpp
@@ -22,7 +22,7 @@ void SingleValue::print(const string& s, const KeyFormatter& formatter) const {
 }
 
 /* ************************************************************************* */
-double SingleValue::operator()(const DiscreteValues& values) const {
+double SingleValue::operator()(const Assignment<Key>& values) const {
   return (double)(values.at(keys_[0]) == value_);
 }
 
diff --git a/gtsam_unstable/discrete/SingleValue.h b/gtsam_unstable/discrete/SingleValue.h
index 3f7f22d6a..93fe38aaa 100644
--- a/gtsam_unstable/discrete/SingleValue.h
+++ b/gtsam_unstable/discrete/SingleValue.h
@@ -55,7 +55,7 @@ class GTSAM_UNSTABLE_EXPORT SingleValue : public Constraint {
   }
 
   /// Calculate value
-  double operator()(const DiscreteValues& values) const override;
+  double operator()(const Assignment<Key>& values) const override;
 
   /// Convert into a decisiontree
   DecisionTreeFactor toDecisionTreeFactor() const override;