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

Testing with types


Type checking is something that is often taken for granted in statically typed languages. With type checking, type errors can be found at compile time, rather than during runtime. In some dynamic languages such as Clojure, type signatures can be declared wherever and whenever they are required, and this technique is termed as optional typing. Type checking can be done using the core.typed library (https://github.com/clojure/core.typed). Using core.typed, the type signature of a var can be checked using type annotations. Type annotations can be declared for any var, which includes values created using a def form, a binding form, or any other construct that creates a var. In this section, we will explore the details of this library.

Note

The following library dependencies are required for the upcoming examples.

[org.clojure/core.typed "0.3.0"]

Also, the following namespaces must be included in your namespace declaration.

(ns my-namespace
  (:require [clojure.core.typed :as t...