Whitespace Mode

I copy and paste text between lots of different applications. Whitespace mode makes it easy to see all the non printing characters that different apps use to format their notes: Evernote, for example, has a habit of insert non breaking spaces in its notes.

Unfortunately, Doom Emacs uses whitespace mode for tab indents only. In order to restore functionality, I had to read up on whitespace mode. Here are my notes, so you don’t have to do the same.

Whitespace

Whitespace uses two ways to visualize blanks: Faces and Display Tables.

  • Faces are used to highlight the background with a color. Whitespace uses font-lock to highlight blank characters. (FontLockMode, rather confusingly, is used for syntax highlighting.)
  • Display table changes the way a character is displayed. For example whitespace-mode uses $ by default to show end of lines.

The whitespace-style variable selects which way blanks are visualized.

whitespace-style

List containing various values. The first is face which enables visualisation using faces

The following will highlight any part of lines > 80 characters

(setq whitespace-line-column 80) ;; limit line length
(setq whitespace-style '(face lines-tail))

whitespace-display-mappings

Specify an alist of mappings for displaying characters.
Each element has the following form:

(KIND CHAR VECTOR…)

Where:

KIND is the kind of character.
It can be one of the following symbols:

    tab-mark        for TAB character
    space-mark      for SPACE or HARD SPACE character
    newline-mark    for NEWLINE character

CHAR is the character to be mapped.

VECTOR is a vector of characters to be displayed in place of CHAR.
The first display vector that can be displayed is used;
if no display vector for a mapping can be displayed, then
that character is displayed unmodified.

The NEWLINE character is displayed using the face given by
whitespace-newline variable.

(newline-mark ?\n    [?\$ ?\n]) ;; Standard emacs $ for EOL
(newline-mark ?\n    [182 ?\n]) ;; Unicode for Pilcrow sign

Doom Emacs Config

Doom Emacs uses Whitespace mode for tab indents only. The following restores functionality. (Solution adopted from this post)

(use-package! whitespace
  :config
  (setq
    whitespace-style '(face tabs tab-mark spaces space-mark trailing newline newline-mark)
    whitespace-display-mappings '(
      (space-mark   ?\     [?\u00B7]     [?.])
      (space-mark   ?\xA0  [?\u00A4]     [?_])
      (newline-mark ?\n    [182 ?\n])
      (tab-mark     ?\t    [?\u00BB ?\t] [?\\ ?\t])))
  (global-whitespace-mode +1))

Whitespace commands

M-x whitespace-mode
M-x global-whitespace-mode
M-x whitespace-newline-mode
M-x whitespace-toggle-options
M-x whitespace-report  Very handy

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