My plan is to use the Arduino to read sensors and control the turnout switches on the track, but I think it is easier to use the RPi to do some initial experimentation with driving relays and other electronic components. I did the typical make-an-LED-blink exercise using the wiringPi library. It wasn't difficult, but I wished there was an interactive way to play with the GPIO pins, rather than going through a cycle of editing, compiling, and executing a C program whenever I wanted to try something.
Then I remembered Forth. Forth was designed as an interactive language for controlling hardware, and seemed like the perfect solution for me.
After looking at a few possibilities for Forth-based solutions, I decided to use Gforth, as it provides a straightforward way to call functions in the wiringPi library without the need to build my own Forth.
Here is my Gforth interface to the wiringPi library: https://github.com/kristopherjohnson/wiringPi_gforth
Now, back to the train set...