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

Executing tasks in parallel


The simultaneous execution of several computations is termed as parallelism. The use of parallelism tends to increase the overall performance of a computation, since the computation can be partitioned to execute on several cores or processors. Clojure has a couple of functions that can be used for the parallelization of a particular computation or task, and we will briefly examine them in this section.

Note

The following examples can be found in src/m_clj/c2/parallel.clj of the book's source code.

Suppose we have a function that pauses the current thread for some time and then returns a computed value, as depicted in Example 2.17:

(defn square-slowly [x]
  (Thread/sleep 2000)
  (* x x))

Example 2.17: A function that pauses the current thread

The function square-slowly in Example 2.17 requires a single argument x. This function pauses the current thread for two seconds and returns the square of its argument x. If the function square-slowly is invoked over a collection...