grack Prolog was a short-lived project that I took on as part of a project course in University. I couldn't find a Prolog engine that met my expectations so, like any good programmer, decided to write my own. I used a number of texts from the library to get a good start at the beginnings of a real Prolog engine. Unfortunately, I ran out of time and decided to drop the program. Perhaps one day I'll pick it up and finish it.