Book Image

Mastering Clojure

By : Akhil Wali
Book Image

Mastering Clojure

By: Akhil Wali

Overview of this book

Clojure is a general-purpose language from the Lisp family with an emphasis on functional programming. It has some interesting concepts and features such as immutability, gradual typing, thread-safe concurrency primitives, and macro-based metaprogramming, which makes it a great choice to create modern, performant, and scalable applications. Mastering Clojure gives you an insight into the nitty-gritty details and more advanced features of the Clojure programming language to create more scalable, maintainable, and elegant applications. You’ll start off by learning the details of sequences, concurrency primitives, and macros. Packed with a lot of examples, you’ll get a walkthrough on orchestrating concurrency and parallelism, which will help you understand Clojure reducers, and we’ll walk through composing transducers so you know about functional composition and process transformation inside out. We also explain how reducers and transducers can be used to handle data in a more performant manner. Later on, we describe how Clojure also supports other programming paradigms such as pure functional programming and logic programming. Furthermore, you’ll level up your skills by taking advantage of Clojure's powerful macro system. Parallel, asynchronous, and reactive programming techniques are also described in detail. Lastly, we’ll show you how to test and troubleshoot your code to speed up your development cycles and allow you to deploy the code faster.
Table of Contents (19 chapters)
Mastering Clojure
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
References
Index

Thinking in logical relations


Now that we are well versed with the various constructs from the core.logic library, let's look at some real world problems that can be solved through logic programming.

Solving the n-queens problem

The n-queens problem is an interesting problem that can be implemented using logical relations. The objective of the n-queens problem is to place n queens on an n x n sized chessboard such that no two queens are a threat to each other. This problem is a generalization of the eight queens problem published by Max Bezzel in 1848, which involves eight queens. In fact, we can actually solve the n-queens problem for any number of queens, as long as we are dealing with four or more queens. Traditionally, this problem can be solved using an algorithmic technique called backtracking, which is essentially an exhaustive search for all possible solutions to a given problem. However, in this section, we will solve it using logical relations.

Let's first define how a queen can...