Book Image

Clojure for Java Developers

Book Image

Clojure for Java Developers

Overview of this book

We have reached a point where machines are not getting much faster, software projects need to be delivered quickly, and high quality in software is more demanding as ever. We need to explore new ways of writing software that helps achieve those goals. Clojure offers a new possibility of writing high quality, multi-core software faster than ever, without having to leave your current platform. Clojure for Java developers aims at unleashing the true potential of the Clojure language to use it in your projects. The book begins with the installation and setup of the Clojure environment before moving on to explore the language in-depth. Get acquainted with its various features such as functional programming, concurrency, etc. with the help of example projects. Additionally, you will also, learn how the tooling works, and how it interacts with the Java environment. By the end of this book, you will have a firm grip on Clojure and its features, and use them effectively to write more robust programs.
Table of Contents (14 chapters)
Clojure for Java Developers
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

The sequence abstraction


Clojure has some unique features that make it different from other Lisps; one of them is the sequence abstraction. You can think of it as an interface that collections comply with. Clojure has a standard API of functions that you can use with sequences. Here are some examples of those functions:

  • The distinct function: This function returns a sequence that includes each element of the original sequence just once:

    (def c [1 1 2 2 3 3 4 4 1 1])
    (distinct c) ;; (1 2 3 4)
  • The take function: This function takes a number of elements from the original sequence:

    (take 5 c) ;; (1 1 2 2 3)
  • The map function: This function applies a function to each element of a sequence and creates a new sequence with these elements:

    (map #(+ % 1) c) ;; (2 2 3 3 4 4 5 5 2 2)

The interesting part here is that these functions receive and return sequences and you can compose them together. It can be seen in the following code:

 (->> c
  (distinct)
  (take 5)
  (reverse)) ;; (4 3 2 1)

;; This is...