What is the difference between ; and ;; in Clojure code comments?

clojure comments marginalia
pauldoo picture pauldoo · Feb 22, 2011 · Viewed 14.2k times · Source

What is the difference between ; and ;; when starting a comment in Clojure? I see that my text editor colours them differently, so I'm assuming there is notionally some difference.

I also see that Marginalia treats them differently:

; Stripped entirely
;; Appears in text section of marginalia
(defn foobar []
   ; Appears in code section of marginalia output
   ;; Again, appears in code section of marginalia output
   6)

Answer

G__ picture G__ · Feb 22, 2011

There is no difference as far as the interpreter is concerned. Think of ; ;; ;;; and ;;;; as different heading levels.

Here is my personal use convention:

;;;; Top-of-file level comments, such as a description of the whole file/module/namespace

;;; Documentation for major code sections (i.e. groups of functions) within the file.

;; Documentation for single functions that extends beyond the doc string (e.g. an explanation of the algorithm within the function)

; In-line comments possibly on a single line, and possibly tailing a line of code

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