Prevent multiple importing of a given module

src/language/ASTModulesImporter.cpp

@@ -19,6 +19,12 @@ ASTModulesImporter::_importModule(ASTNode& import_node)
   ASTNode& module_name_node     = *import_node.children[0];
   const std::string module_name = module_name_node.string();
 
+  if (auto [i_module_name, success] = m_imported_modules.insert(module_name); not success) {
+    std::cout << " * ignoring  '" << rang::fgB::green << module_name << rang::style::reset
+              << "' module, already imported\n";
+    return;
+  }
+
   std::cout << " * importing '" << rang::fgB::green << module_name << rang::style::reset << "' module\n";
 
   if (module_name == "math") {

src/language/ASTModulesImporter.hpp

@@ -3,10 +3,14 @@
 
 #include <ASTNode.hpp>
 
+#include <set>
+#include <string>
+
 class SymbolTable;
 
 class ASTModulesImporter
 {
+  std::set<std::string> m_imported_modules;
   SymbolTable& m_symbol_table;
 
   void _importModule(ASTNode& import_node);