I will have to read this, should I fine the time. I learned Prolog in High School, it was a challenge at first -- I didn't get it right away. But when I did I

I will have to read this, should I fine the time. I learned Prolog in High School, it was a challenge at first -- I didn't get it right away. But when I did I was amazed. Yet I have an ongoing problem with Prolog that I have never fully put my finger on exactly -- it's something about how side-effects intermix with pure logic. I find it makes the flow of activity hard to follow. Can anyone else relate to this and perhaps explain it better?