diff --git a/gtsam/discrete/DiscretePrior.cpp b/gtsam/discrete/DiscretePrior.cpp
new file mode 100644
index 000000000..3941e0199
--- /dev/null
+++ b/gtsam/discrete/DiscretePrior.cpp
@@ -0,0 +1,50 @@
+/* ----------------------------------------------------------------------------
+
+ * GTSAM Copyright 2010, Georgia Tech Research Corporation,
+ * Atlanta, Georgia 30332-0415
+ * All Rights Reserved
+ * Authors: Frank Dellaert, et al. (see THANKS for the full author list)
+
+ * See LICENSE for the license information
+
+ * -------------------------------------------------------------------------- */
+
+/**
+ *  @file DiscretePrior.cpp
+ *  @date December 2021
+ *  @author Frank Dellaert
+ */
+
+#include <gtsam/discrete/DiscretePrior.h>
+
+namespace gtsam {
+
+void DiscretePrior::print(const std::string& s,
+                          const KeyFormatter& formatter) const {
+  Base::print(s, formatter);
+}
+
+double DiscretePrior::operator()(size_t value) const {
+  if (nrFrontals() != 1)
+    throw std::invalid_argument(
+        "Single value operator can only be invoked on single-variable "
+        "priors");
+  DiscreteValues values;
+  values.emplace(keys_[0], value);
+  return Base::operator()(values);
+}
+
+std::vector<double> DiscretePrior::pmf() const {
+  if (nrFrontals() != 1)
+    throw std::invalid_argument(
+        "DiscretePrior::pmf only defined for single-variable priors");
+  const size_t nrValues = cardinalities_.at(keys_[0]);
+  std::vector<double> array;
+  array.reserve(nrValues);
+  for (size_t v = 0; v < nrValues; v++) {
+    array.push_back(operator()(v));
+  }
+  return array;
+}
+
+}  // namespace gtsam
diff --git a/gtsam/discrete/DiscretePrior.h b/gtsam/discrete/DiscretePrior.h
index 96a0b6f3a..f44df4987 100644
--- a/gtsam/discrete/DiscretePrior.h
+++ b/gtsam/discrete/DiscretePrior.h
@@ -72,37 +72,18 @@ class GTSAM_EXPORT DiscretePrior : public DiscreteConditional {
   /// GTSAM-style print
   void print(
       const std::string& s = "Discrete Prior: ",
-      const KeyFormatter& formatter = DefaultKeyFormatter) const override {
-    Base::print(s, formatter);
-  }
+      const KeyFormatter& formatter = DefaultKeyFormatter) const override;
+
   /// @}
   /// @name Standard interface
   /// @{
 
   /// Evaluate given a single value.
-  double operator()(size_t value) const {
-    if (nrFrontals() != 1)
-      throw std::invalid_argument(
-          "Single value operator can only be invoked on single-variable "
-          "priors");
-    DiscreteValues values;
-    values.emplace(keys_[0], value);
-    return Base::operator()(values);
-  }
+  double operator()(size_t value) const;
 
   /// Evaluate given a single value.
-  std::vector<double> pmf() const {
-    if (nrFrontals() != 1)
-      throw std::invalid_argument(
-          "DiscretePrior::pmf only defined for single-variable priors");
-    const size_t nrValues = cardinalities_.at(keys_[0]);
-    std::vector<double> array;
-    array.reserve(nrValues);
-    for (size_t v = 0; v < nrValues; v++) {
-      array.push_back(operator()(v));
-    }
-    return array;
-  }
+  std::vector<double> pmf() const;
+
   /// @}
 };
 // DiscretePrior