Prolog Coding Horror

# Summary This article outlines common pitfalls in Prolog programming that lead to defective code, including losing solutions through impure constructs (like cuts and conditionals), introducing implicit dependencies via global state modification, producing impure output through direct printing instead of letting the toplevel handle results, and relying on outdated low-level language constructs instead of modern features like CLP(FD). The author argues that following a small set of rules—such as using clean data structures, constraints, and proper argument threading—results in more reliable, testable, and maintainable Prolog programs.