diff --git a/analyze/aps-bind.c b/analyze/aps-bind.c
index 5b6b0da..cac4c15 100644
--- a/analyze/aps-bind.c
+++ b/analyze/aps-bind.c
@@ -42,8 +42,8 @@ struct env_item {
 };
 typedef struct env_item *SCOPE;
 
-static Declaration module_TYPE;
-static Declaration module_PHYLUM;
+Declaration module_TYPE;
+Declaration module_PHYLUM;
 
 static TypeEnvironment current_type_env = 0;
 
diff --git a/analyze/aps-bind.h b/analyze/aps-bind.h
index 82ee8fa..f5e38b4 100644
--- a/analyze/aps-bind.h
+++ b/analyze/aps-bind.h
@@ -33,4 +33,7 @@ extern int decl_namespaces(Declaration d);
 extern int bind_debug;
 #define PRAGMA_ACTIVATION 1
 
+extern Declaration module_TYPE;
+extern Declaration module_PHYLUM;
+
 #endif
diff --git a/analyze/aps-type.c b/analyze/aps-type.c
index c09dce2..4d988ef 100644
--- a/analyze/aps-type.c
+++ b/analyze/aps-type.c
@@ -495,9 +495,6 @@ static void* validate_canonicals(void* ignore, void*node) {
   return node;
 }
 
-static Declaration module_TYPE;
-static Declaration module_PHYLUM;
-
 static void* set_root_phylum(void *ignore, void *node)
 {
   switch (ABSTRACT_APS_tnode_phylum(node))
diff --git a/analyze/canonical-signature.c b/analyze/canonical-signature.c
index fea01ac..9573a49 100644
--- a/analyze/canonical-signature.c
+++ b/analyze/canonical-signature.c
@@ -10,8 +10,6 @@ static CanonicalSignatureSet from_declaration(Declaration decl);
 static CanonicalSignatureSet substitute_canonical_signature_set_actuals(CanonicalType* source, CanonicalSignatureSet sig_set);
 static int canonical_signature_compare(CanonicalSignature *sig1, CanonicalSignature *sig2);
 
-static Declaration module_TYPE;
-static Declaration module_PHYLUM;
 static bool initialized = false;
 
 /**
@@ -352,9 +350,9 @@ static int canonical_signature_compare(CanonicalSignature *sig1, CanonicalSignat
     return sig1->is_var - sig2->is_var;
   }
 
-  if (tnode_line_number(sig1->source_class) != tnode_line_number(sig2->source_class))
+  if (sig1->source_class != sig2->source_class)
   {
-    return tnode_line_number(sig1->source_class) - tnode_line_number(sig2->source_class);
+    return (sig1->source_class > sig2->source_class) ? 1 : -1;
   }
 
   if (sig1->num_actuals != sig2->num_actuals)
diff --git a/analyze/canonical-type.c b/analyze/canonical-type.c
index e6860d5..e74e347 100755
--- a/analyze/canonical-type.c
+++ b/analyze/canonical-type.c
@@ -1006,9 +1006,12 @@ CanonicalType *canonical_type_join(CanonicalType *ctype_outer, CanonicalType *ct
  * Comparator for two canonical types
  * @param ctype1 first canonical type
  * @param ctype2 second canonical type
+ * @param ctype1_mdecl_result Result decl from the source (inherited) module, or NULL
+ * @param ctype2_mdecl_result Result decl from the target (implementing) module, or NULL
  * @return integer value representing the comparison
  */
-int canonical_type_compare(CanonicalType *ctype1, CanonicalType *ctype2)
+int canonical_type_compare2(CanonicalType *ctype1, CanonicalType *ctype2,
+                           Declaration ctype1_mdecl_result, Declaration ctype2_mdecl_result)
 {
   if (ctype1->key != ctype2->key)
   {
@@ -1022,19 +1025,23 @@ int canonical_type_compare(CanonicalType *ctype1, CanonicalType *ctype2)
     struct Canonical_use_type *canonical_use_type1 = (struct Canonical_use_type *)ctype1;
     struct Canonical_use_type *canonical_use_type2 = (struct Canonical_use_type *)ctype2;
 
-    return tnode_line_number(canonical_use_type1->decl) - tnode_line_number(canonical_use_type2->decl);
+    Declaration d1 = (ctype1_mdecl_result != NULL && canonical_use_type1->decl == ctype1_mdecl_result) ? ctype2_mdecl_result : canonical_use_type1->decl;
+    Declaration d2 = canonical_use_type2->decl;
+    return (d1 > d2) ? 1 : (d1 < d2) ? -1 : 0;
   }
   case KEY_CANONICAL_QUAL:
   {
     struct Canonical_qual_type *canonical_qual_type1 = (struct Canonical_qual_type *)ctype1;
     struct Canonical_qual_type *canonical_qual_type2 = (struct Canonical_qual_type *)ctype2;
 
-    if (tnode_line_number(canonical_qual_type1->decl) != tnode_line_number(canonical_qual_type2->decl))
+    Declaration d1 = (ctype1_mdecl_result != NULL && canonical_qual_type1->decl == ctype1_mdecl_result) ? ctype2_mdecl_result : canonical_qual_type1->decl;
+    Declaration d2 = canonical_qual_type2->decl;
+    if (d1 != d2)
     {
-      return tnode_line_number(canonical_qual_type1->decl) - tnode_line_number(canonical_qual_type2->decl);
+      return (d1 > d2) ? 1 : -1;
     }
 
-    return canonical_type_compare(canonical_qual_type1->source, canonical_qual_type2->source);
+    return canonical_type_compare2(canonical_qual_type1->source, canonical_qual_type2->source, ctype1_mdecl_result, ctype2_mdecl_result);
   }
   case KEY_CANONICAL_FUNC:
   {
@@ -1043,10 +1050,10 @@ int canonical_type_compare(CanonicalType *ctype1, CanonicalType *ctype2)
 
     if (canonical_function_type1->num_formals != canonical_function_type2->num_formals)
     {
-      return canonical_function_type1->num_formals - canonical_function_type2->num_formals > 0 ? 1 : -1;
+      return (canonical_function_type1->num_formals > canonical_function_type2->num_formals) ? 1 : -1;
     }
 
-    int return_type_comp = canonical_type_compare(canonical_function_type1->return_type, canonical_function_type2->return_type);
+    int return_type_comp = canonical_type_compare2(canonical_function_type1->return_type, canonical_function_type2->return_type, ctype1_mdecl_result, ctype2_mdecl_result);
     if (return_type_comp != 0)
     {
       return return_type_comp;
@@ -1055,7 +1062,7 @@ int canonical_type_compare(CanonicalType *ctype1, CanonicalType *ctype2)
     int i;
     for (i = 0; i < canonical_function_type1->num_formals; i++)
     {
-      int formal_type_comp = canonical_type_compare(canonical_function_type1->param_types[i], canonical_function_type2->param_types[i]);
+      int formal_type_comp = canonical_type_compare2(canonical_function_type1->param_types[i], canonical_function_type2->param_types[i], ctype1_mdecl_result, ctype2_mdecl_result);
       if (formal_type_comp != 0)
       {
         return formal_type_comp;
@@ -1065,7 +1072,7 @@ int canonical_type_compare(CanonicalType *ctype1, CanonicalType *ctype2)
     return 0;
   }
   default:
-    fatal_error("canonical_type_compare failed");
+    fatal_error("canonical_type_compare2 failed");
     return 0;
   }
 }
diff --git a/analyze/canonical-type.h b/analyze/canonical-type.h
index 6833816..8d616f2 100755
--- a/analyze/canonical-type.h
+++ b/analyze/canonical-type.h
@@ -65,13 +65,29 @@ CanonicalType *canonical_type_join(CanonicalType *ctype_outer, CanonicalType *ct
  */
 CanonicalType *new_canonical_type_use(Declaration decl);
 
+/**
+ * Compares two canonical types with Result-decl substitution.
+ * The inherited module's Result maps to the implementing module's Result.
+ * @param ctype1 Canonical type to compare
+ * @param ctype2 Canonical type to compare against
+ * @param ctype1_mdecl_result Result decl of ctype1's enclosing module
+ * @param ctype2_mdecl_result Result decl of ctype2's enclosing module
+ * @return Integer value representing comparison of two canonical types
+ */
+int canonical_type_compare2(CanonicalType *ctype1, CanonicalType *ctype2,
+                            Declaration ctype1_mdecl_result,
+                            Declaration ctype2_mdecl_result);
+
 /**
  * Compares two canonical types
- * @param ctype1 Canonical type A
- * @param ctype2 Canonical type B
+ * @param ctype1 Canonical type to compare
+ * @param ctype2 Canonical type to compare against
  * @return Integer value representing comparison of two canonical types
  */
-int canonical_type_compare(CanonicalType *ctype1, CanonicalType *ctype2);
+static inline int canonical_type_compare(CanonicalType *ctype1, CanonicalType *ctype2)
+{
+  return canonical_type_compare2(ctype1, ctype2, NULL, NULL);
+}
 
 /**
  * Given a canonical type, it returns a Declaration
diff --git a/aps2scala/dump-scala.cc b/aps2scala/dump-scala.cc
index c4e8750..b3910da 100644
--- a/aps2scala/dump-scala.cc
+++ b/aps2scala/dump-scala.cc
@@ -181,10 +181,10 @@ void dump_formal(Declaration formal, ostream&os)
   if (KEYseq_formal == Declaration_KEY(formal)) os << "*";
 }
 
-void dump_function_prototype(string name, Type ft, bool dump_anchor_actual, ostream& oss)
+void dump_function_prototype(string name, Type ft, bool dump_anchor_actual, bool override_needed, ostream& oss)
 {
-  oss << indent() << "val v_" << name << " = f_" << name << " _;\n";
-  oss << indent() << "def f_" << name << "(";
+  oss << indent() << (override_needed ? "override " : "") << "val v_" << name << " = f_" << name << " _;\n";
+  oss << indent() << (override_needed ? "override " : "") << "def f_" << name << "(";
 
   bool started = false;
   Declarations formals = function_type_formals(ft);
@@ -1392,7 +1392,7 @@ static void dump_scala_pattern_function(
   
   if (!body) {
     // the constructor function:
-    dump_function_prototype(name,ft,dump_anchor_actual,oss);
+    dump_function_prototype(name,ft,dump_anchor_actual,false /* override_needed */,oss);
     oss << " = c_" << name << args;
     if (is_syntax) oss << ".register";
     oss << ";\n";
@@ -1451,6 +1451,78 @@ void dump_scala_Declaration_header(Declaration decl, ostream& oss)
   }
 }
 
+// Recursive helper function to check given a surrounding declaration (module_decl, class_decl or type_decl)
+// if it contains a function declaration that matches the given name and return type
+// if true then override would be needed otherwise not needed
+static void type_has_service_function(Declaration decl, Symbol fdecl_name, vector<Declaration>& found_decls) {
+  switch (Declaration_KEY(decl)) {
+  case KEYsome_type_decl: {
+    Type type = some_type_decl_type(decl);
+    switch (Type_KEY(type))
+    {
+    case KEYno_type: {
+      bool is_phylum = Declaration_KEY(decl) == KEYphylum_decl;
+      return type_has_service_function(is_phylum ? module_PHYLUM : module_TYPE, fdecl_name, found_decls);
+    }
+    case KEYtype_use:
+      return type_has_service_function(canonical_type_decl(canonical_type(type)), fdecl_name, found_decls);
+    case KEYtype_inst:
+      return type_has_service_function(USE_DECL(module_use_use(type_inst_module(type))), fdecl_name, found_decls);
+    default:
+      break;
+    }
+  }
+  case KEYsome_class_decl: {
+    Block body = some_class_decl_contents(decl);
+    Declaration item;
+    for (item = first_Declaration(block_body(body)); item != NULL; item = DECL_NEXT(item)) {
+      switch (Declaration_KEY(item)) {
+      case KEYsome_function_decl:
+        if (def_name(some_function_decl_def(item)) == fdecl_name) {
+          found_decls.push_back(item);
+        }
+
+        break;
+      default:
+        break;
+      }
+    }
+
+    if (decl == module_PHYLUM || decl == module_TYPE) {
+      return;
+    } else {
+      type_has_service_function(some_class_decl_result_type(decl), fdecl_name, found_decls);
+    }
+  }
+  default:
+    break;
+  }
+}
+
+Declaration get_enclosing_some_class_decl(Declaration source) {
+  void* node = (void*)source;
+  while (node != NULL) {
+    switch (ABSTRACT_APS_tnode_phylum(node)) {
+    case KEYDeclaration: {
+      Declaration decl = (Declaration) node;
+      switch (Declaration_KEY(decl)) {
+      case KEYsome_class_decl:
+        return decl;
+      default:
+        break;
+      }
+      break;
+    }
+    default:
+      break;
+    }
+
+    node = tnode_parent(node);
+  }
+
+  return NULL;
+}
+
 void dump_scala_Declaration(Declaration decl,ostream& oss)
 {
   const char *name = 0;
@@ -1922,7 +1994,44 @@ void dump_scala_Declaration(Declaration decl,ostream& oss)
       Type fty = function_decl_type(decl);
       Declaration rdecl = first_Declaration(function_type_return_values(fty));
       Block b = function_decl_body(decl);
-      dump_function_prototype(name,fty,false /* dump_anchor_actual */,oss);
+      Declaration mdecl = get_enclosing_some_class_decl(decl);
+      bool override_needed = false;
+      if (mdecl != NULL) {
+        vector<Declaration> found_fdecls;
+        type_has_service_function(some_class_decl_result_type(mdecl), def_name(declaration_def(decl)), found_fdecls);
+
+        auto cftype2 = (struct Canonical_function_type *)canonical_type(fty);
+        // Result declaration of the current (implementing) module
+        Declaration current_result = some_class_decl_result_type(mdecl);
+        for (auto& found_fdecl : found_fdecls) {
+          auto cftype1 = (struct Canonical_function_type *)canonical_type(some_function_decl_type(found_fdecl));
+          // Result declaration of the inherited (source) module
+          Declaration found_mdecl = get_enclosing_some_class_decl(found_fdecl);
+          Declaration ctype1_mdecl_result = found_mdecl ? some_class_decl_result_type(found_mdecl) : NULL;
+          if (cftype1->num_formals == cftype2->num_formals) {
+            bool formals_type_match = true;
+            for (int i = 0; i < cftype1->num_formals; ++i) {
+              if (canonical_type_compare2(cftype1->param_types[i], cftype2->param_types[i],
+                                         ctype1_mdecl_result, current_result) != 0) {
+                formals_type_match = false;
+              }
+            }
+
+            if (formals_type_match) {
+              if (canonical_type_compare2(cftype1->return_type, cftype2->return_type,
+                                         ctype1_mdecl_result, current_result) == 0) {
+                override_needed = true;
+                break;
+              } else {
+                aps_error(decl, "Function %s has same name as inherited function but different return type; overriding not possible since return types are incompatible", decl_name(decl));
+                return;
+              }
+            }
+          }
+        }
+      }
+
+      dump_function_prototype(name, fty, false /* dump_anchor_actual */, override_needed, oss);
 
       // three kinds of definitions:
       // 1. the whole thing: a non-empty body: