14. Modules

Modules are used for creating large-scale variable namespaces. Modules let you build programs and program segments that have private variables. Only the variables you export are visible from outside the module. Module variables are similar to global variables of other languages.

Some languages have module systems with distinct support for exporting variables, functions, types, and classes. Dylan modules operate only on variables. Because functions and classes are stored in variables, you can control access to them by controlling access to the variables that contain them. If you export the variable containing a class or function, you have effectively exported the class or function. If you do not export the variable, then you have effectively kept the class or function private.[28]