Are all Prosody modules pure-lua, or can/do some have a C/binary component to them? I note that the API documentation describes only lua bits, at least.
They are generally pure Lua, but they can load binary libraries. Some existing such libraries can be found in most distro repositories or on luarocks.org. Lua also has a well designed API in case you need to write your own bindings to something.
If you have questions about how to do something specific we're very approachable and happy to share our knowledge :)
If you have questions about how to do something specific we're very approachable and happy to share our knowledge :)