Book Image

Learning ClojureScript

By : W. David Jarvis, Allen Rohner
Book Image

Learning ClojureScript

By: W. David Jarvis, Allen Rohner

Overview of this book

Clojure is an expressive language that makes it possible to easily tackle complex software development challenges. Its bias toward interactive development has made it a powerful tool, enabling high developer productivity. In this book, you will first learn how to construct an interactive development experience for ClojureScript.. You will be guided through ClojureScript language concepts, looking at the basics first, then being introduced to advanced concepts such as functional programming or macro writing. After that, we elaborate on the subject of single page web applications, showcasing how to build a simple one, then covering different possible enhancements. We move on to study more advanced ClojureScript concepts, where you will be shown how to address some complex algorithmic cases. Finally, you'll learn about optional type-checking for your programs, how you can write portable code, test it, and put the advanced compilation mode of the Google Closure Compiler to good use.
Table of Contents (15 chapters)
Learning ClojureScript
About the Authors
About the Reviewer


Now that you've had a basic introduction to ClojureScript's data structures, let's talk a bit about immutability. Almost all of ClojureScript's data types are immutable, which means that once they're defined, including them in an expression won't change their underlying value. This concept can take a bit of getting used to, so let's take a look at a few examples. As a point of contrast, we'll use JavaScript as an example of a language where data types are mutable.

Let's start with an example using a vector. First, we'll define a vector with one element in it, the integer 1:

cljs.user=> (def x [1])
;; => #'cljs.user/x

Now, we'll call conj on x. We've already talked a bit about how conj works earlier in this chapter, but just to review, the conj function returns a new vector that consists of the original vector with any of the following arguments added to the original vector:

cljs.user=> (conj x 2)
;; => [1 2]

Notice that the value of x itself hasn't changed-it's still...