Modules gain access to declarations and functionality of other modules using the import statement. For example, a main module cannot use types or procedures defined in the IO interface until it explicitly imports the definitions using the IMPORT statement like this:
IMPORT IO;
Once you import an interface this way, you can refer to an individual item in that interface using a Module.Declaration syntax. (That is, you prefix the name of an identifier with its interface and a period in between the two.) In our example, we can access IO.Put procedure via:
IO.Put ("Hello, world.");