Programming Clojure, 3rd Edition

Comments

There are several ways to create comments in Clojure. The most common is to use ;, which creates a comment to the end of the line. While everything after the first ; is ignored, you’ll often see multiple semicolons to make a greater visual impact:

;; this is a comment

Clojure also contains a comment macro that ignores its body and returns nil. This is useful to wrap around a block of existing code. However, because it’s still read by the Clojure reader, it must be valid code.

(comment
  (defn ignore-me []
    ;; not done yet
    ))

One common use of the comment macro is to save a chunk of utility or test code in a comment block at the end of the file, which is useful in combination with REPL-based development.

Clojure also contains ...