A Very Gentle Introduction to Relational Programming & Functional Programming by David Nolen.
From the webpage:
This tutorial will guide you through the magic and fun of combining relational programming (also known as logic programming) with functional programming. This tutorial does not assume that you have any knowledge of Lisp, Clojure, Java, or even functional programming. The only thing this tutorial assumes is that you are not afraid of using the command line and you have used at least one programming language before in your life.
A fairly short tutorial but one where “relational” in the title is likely to result in confusion. Here “relational” is meant in the sense of “logical.”
Another one of those ambiguity problems.