I started reading The Joy of Clojure, seems like a great book and I like its example code convention. I’m documenting it here because I’ll adopt it on my blog and I want to be able to link to it. I’ll call it the joyful Clojure example code convention.

A simple piece of Clojure code looks like this:

(* 2 10)

If you run it on the REPL it looks like this:

user> (* 2 10)

The first example, it’s just the code, with no return value, the second one, shows the return value, but when you have several lines it becomes cumbersome to copy and paste:

user> (* 2 10)
user> (* 2 11)
user> (* 2 12)

The Joy of Clojure code convention solves both problems by removing the prompt and leaving return values in comments:

(* 2 10)
;=> 20
(* 2 11)
;=> 22
(* 2 12)
;=> 24

Now you can copy and paste and still have the results.

If the snippet prints something, it will also be displayed but without the arrow, like this:

(println "Hello world")
; Hello world
;=> nil