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

Using monoids


Let's start by exploring monoids. In order to define a monoid, we must first understand what a semigroup is.

Note

The following examples can be found in src/m_clj/c6/ monoids.clj of the book's source code.

A semigroup is an algebraic structure that supports an associative binary operation. A binary operation, say , is termed associative if the operation produces the same result as the operation . A monoid is in fact a semigroup with an additional property, as we will see ahead.

The mappend function from the cats.core namespace will associatively combine a number of instances of the same type and return a new instance of the given type. If we are dealing with strings or vectors, the mappend operation is implemented by the standard concat function. Thus, strings and vectors can be combined using the mappend function, as shown here:

user> (cc/mappend "12" "34" "56")
"123456"
user> (cc/mappend [1 2] [3 4] [5 6])
[1 2 3 4 5 6]

As strings and vectors support the associative mappend...