new typecheck start

include/nodes/type_nodes.hpp

@@ -280,7 +280,7 @@ public:
 
   void clear_resolved_generic_names() { resolved_generic_names_.clear(); }
 
-  // -- deal with local types
+  // -- deal with local types // not needed ??
 
   bool add_local_type(const std::string &name);
 
@@ -301,6 +301,21 @@ public:
     local_name_typeclasses_.clear();
   }
 
+  //
+
+  enum class UnifyModePolicy { // TODO: proper modes for modifier
+    Ignore,                    // all mode differences ignored
+    ApplyStrongest,            // unique > shared, modes changed
+    CheckLeftIsSubmode,        // only check is performed
+  };
+
+  // TODO: next iteration of type check
+  bool unify(TypeProxy left_proxy, TypeProxy right_proxy,
+             UnifyModePolicy policy);
+
+  bool resolve(TypeProxy generic,
+               const Type &replacement /*  TODO , Mode mode = {}*/);
+
 private:
   Type *get_type(size_t id) { return &storage_.at(id); }