Conventions

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "Hence, for trees that are represented as sequences, we should use the seq-zip function instead."

A block of code is set as follows:

(f/defun fibo
  ([0] 0N)
  ([1] 1N)
  ([n] (+ (fibo (- n 1))
          (fibo (- n 2)))))

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

(f/defun fibo
  ([0] 0N)
  ([1] 1N)
  ([n] (+ (fibo (- n 1))
          (fibo (- n 2)))))

Any command-line input or output is written as follows:

$ lein repl

Another simple convention that we use is to always show the Clojure code that's entered in the REPL (read-evaluate-print-loop) starting with the user> prompt. In practice, this prompt will change depending on the Clojure namespace that we are currently using. However, for simplicity, code in the REPL always starts with the user> prompt in this book, as follows:

user> (cons 0 ())
(0)
user> (cons 0 nil)
(0)
user> (rest (cons 0 nil))
()

For convenience, the REPL output in this book is pretty-printed (using the clojure.pprint/pprint function). Objects that are printed in the REPL output are enclosed within the #< and > symbols. We must note that the output of the time form in your own REPL may not completely match the output shown in the code examples of this book. Rather, the use of time forms is meant to give you an idea of the scale of the time taken to execute a given expression. Similarly, the output of the code examples that use the rand-int function may not exactly match the output in your REPL.

Some examples in this book use ClojureScript, and the files for these examples will have a .cljs extension. Also, all macros used in these examples will have to be explicitly included using the :require-macros clause of the ns form. The HTML and CSS files associated with the ClojureScript examples in this book will not be shown in this book, but can always be found in the book's code bundle.