Im very new to ECJ and GP so I need a little Basic help. I want to

realize a control program for a robot with servo motors and some 
IR-Sensors. To control him I take something like that:

Terminal Set = {IR0, IR1, ..IRn, Constant:0.255}
Function Set = {+, -, /, *, sleep(x), SetServo0, SetServo1,..SetServon, 
Proc4, <, >, ...}

As I understand the Proc-Function (like in Koza's Ant control) is only a 
way to express a serial chain of commands. It has no return value and 
therfore can't be a node to most other functions like +, -, sleep etc. 
(while normal arithmetic functions with a return value are 
"node-compŘatible" to each other)

How can I manage this constraints?