It works fine to the degree that the module is stateless and is designed to be used as a library, functionally scoped. To the degree that a module is stateful,

It works fine to the degree that the module is stateless and is designed to be used as a library, functionally scoped. To the degree that a module is stateful, designed to be used as a framework, and have long-term persistence, it doesn't. OK for calculations; less than OK for a network server or data store.