Is there documentation of the HAL and GUI modules?

I’ve been looking but i can’t seem to find any documentation about the modules.
How am i supposed to work on anything without documentation?

Yes, there is documentation for the HAL and GUI modules of each exercise.

You can access to it:
(a) through the “graduation cap” button at the top right area of each exercise webpage.
(b) looking for the user documentation page of RoboticsAcademy (Robotics-Academy exercises - Robotics Academy). For instance, the ‘follow line’ exercise has this user documentation page: Visual Follow Line - Robotics Academy