Definition
Modules are defined by simply creating an Alan source file. The name of the module is simply the name of the file minus the extension, unless the file is named index.ln in which case the name of the module is it's parent directory for anything referencing it. (This allows a former something.ln module to become something/index.ln and have a companion something/submodule.ln if it grows too big but should still be thought of as a singular unit.)
The portions of a module that are private to that module are not exported, while the portions intended to be public have an export keyword prefixed to them.