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

Transducers in action


In this section, we will examine how transducers are implemented. We will also get a basic idea of how our own transducible source of data can be implemented.

Managing volatile references

Some transducers can internally use state. It turns out that the existing reference types, such as atoms and refs, aren't fast enough for the implementation of transducers. To circumvent this problem, transducers also introduce a new volatile reference type. A volatile reference represents a mutable variable that will not be copied into the thread-local cache. Also, volatile references are not atomic. They are implemented in Java using the volatile keyword with a java.lang.Object type.

Note

The following examples can be found in src/m_clj/c5/volatile.clj of the book's source code.

We can create a new volatile reference using the volatile! function. The value contained in the volatile state can then be retrieved using the @ reader macro or a deref form. The vreset! function can be used to...