Customer Reviews

Learning to Build and Comprehend Complex Information Structures: Prolog as a Case Study (Contemporary Studies in Cognitive Science and Technology)

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This is a wonderful book for many reasons, but the biggest wonder was that it was ever published! It documents obscure research about an obscure programming language--and the point of the research is to find out why it is so obscure!

If you are a big fan of prolog, but are still wondering why it didn't take off, this book will tell you. For me, the biggest take away messages are these:

1. The very uniformity of the syntax--which makes Prolog "beautiful" in a sense--is a source of obscurity, because since everything is just clauses, its hard to tell what any particular clause is doing. In, say, C, its easy to tell if something is a for-loop or not--the keyword "for" is right there. But in prolog, iteration over a range of values looks pretty much like any other programming statement. There is no syntactic differentiation to help you understand the semantics.

2. In order to understand a prolog program, you pretty much have to be a master of redaction criticism. For example, a prolog program to sum up the values of all the integers in a list of integers is typically written by taking the code for the member/2 function and editing it--adding here an accumulator, there a summation, etc. This is called "Skeletons and Techniques" by Lee Naish and other exponents. It is a very powerful way to develop prolog programs, but someone else wanting to understand _your_ prolog program must first understand how member/2 works, then they must work backwards from the changes you've made to it, first determining how you've edited member/2 and what your editorial changes mean, before they can understand your code. Its very tricky!

Talk about a book which isn't for everyone! But if you are in the business of designing languages, there's lots of interesting insights here just waiting to be gleaned.