pigps is a Common Lisp library for using Adafruit's "Ultimate GPS", using my Common Lisp binding to wiringPi.
First, hook up the Ultimate GPS to your Raspberry Pi as explained on the Adafruit website.
Next, get the code. The easiest way is to clone the library into your ASDF/QuickLisp search path and load it with QuickLisp.
cd ~/src/lisp git clone https://github.com/jl2/pigps
Next, start Slime (or just a REPL) as root:
sudo emacs --user $USER -f slime
Finally, load the library and get your current location:
(ql:quickload 'pigps) (pigps:current-location)
If everything is configured and working correctly, the result, a pigps:gps-datapoint object, should be printed.
For the time being, this library ignores many of the NMEA fields returned by the Ultimate GPS, such as the VTG, GSA, and GSV fields.