Seven Languages in Seven Weeks

Chapter 4Prolog

Sally Dibbs, Dibbs Sally. 461-0192.

Raymond

Ah, Prolog. Sometimes spectacularly smart, other times just as frustrating. You’ll get astounding answers only if you know how to ask the question. Think Rain Man.^[7] I remember watching Raymond, the lead character, rattle off Sally Dibbs’ phone number after reading a phone book the night before, without thinking about whether he should. With both Raymond and Prolog, I often find myself asking, in equal parts, “How did he know that?” and “How didn’t he know that?” He’s a fountain of knowledge, if you can only frame your questions in the right way.

Prolog represents a serious departure from the other languages we’ve encountered so far. Both Io and Ruby are called imperative languages ...