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 functors


Next, let's take a look at functors. A functor is essentially a value in a container or a computational context. The fmap function must be implemented by a functor. This function applies a supplied function to the value contained in a functor. In object-oriented terminology, a functor can be thought of as a generic type with a single abstract method fmap. In a way, reference types, such as refs and atoms, can be thought of as functors that save results, as a reference type applies a function to its contained value in order to obtain the new value that should be stored in it.

Note

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

The fmap function from the cats.core namespace takes two arguments: a function and a functor. A functor itself defines what happens when an instance of the functor is passed to the fmap function. The cats library extends vectors as functors. When a vector is passed to the fmap function along with a function,...