Book Image

Clojure High Performance Programming

By : Shantanu Kumar
Book Image

Clojure High Performance Programming

By: Shantanu Kumar

Overview of this book

<p>Clojure is a young, dynamic, functional programming language that runs on the Java Virtual Machine. It is built with performance, pragmatism, and simplicity in mind. Like most general purpose languages, Clojure’s features have different performance characteristics that one should know in order to write high performance code.<br /><br />Clojure High Performance Programming is a practical, to-the-point guide that shows you how to evaluate the performance implications of different Clojure abstractions, learn about their underpinnings, and apply the right approach for optimum performance in real-world programs.<br /><br />This book discusses the Clojure language in the light of performance factors that you can exploit in your own code.</p> <p>You will also learn about hardware and JVM internals that also impact Clojure’s performance. Key features include performance vocabulary, performance analysis, optimization techniques, and how to apply these to your programs. You will also find detailed information on Clojure's concurrency, state-management, and parallelization primitives.</p> <p>This book is your key to writing high performance Clojure code using the right abstraction, in the right place, using the right technique.</p>
Table of Contents (15 chapters)
Clojure High Performance Programming
Credits
About the Author
Acknowledgments
About the Reviewers
www.PacktPub.com
Preface
Index

Numerics, boxing, and primitives


Numerics are scalars. The discussion on numerics was deferred until this chapter for the sole reason that the numerics implementation in Clojure has strong Java underpinnings. Since Version 1.3, Clojure has settled with 64-bit numerics as the default. Now, long and double are idiomatic and are the default numeric types. Note that these are primitive Java types, not objects. Primitives in Java lead to high performance and have several optimizations associated with them at compiler and runtime levels. A local primitive is created on the stack (hence does not contribute to heap allocation and GC) and can be accessed directly without any kind of dereferencing. In Java, there also exist object equivalents of the numeric primitives, known as boxed numerics — these are regular objects that are allocated on the heap. The boxed numerics are also immutable objects, which mean not only does the JVM need to dereference the stored value when reading it, but also needs...