I also use include
- for a project-wide 'prelude' which has pragmas and common imports in it
- for platform-specific code (audio module includes either gba/audio or
pc/audio)
- for templating (using stdtmpl filter and include the source file into some
proc to turn it into a usable template)
- for config DSLs (write the config exactly how you want and include it into a
place where the config commands actually mean something) - this works great with
nimscript
- for making user-defined types accessible through library code (the library
becomes a framework that knows about the assets in the user's project)