Make apheleia-mode lighter customizable (#143)

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Co-authored-by: Radon Rosborough <radon@intuitiveexplanations.com>

CHANGELOG.md

@@ -4,6 +4,9 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog].
 
 ## Unreleased
+### Features
+* `apheleia-mode` lighter is now customizable ([#143]).
+
 ### Enhancements
 * shfmt uses 4 spaces instead of tabs by default.
 * Formatters using `'filepath` (OCamlFormat and Prettier) are no
@@ -71,6 +74,7 @@ The format is based on [Keep a Changelog].
 [#128]: https://github.com/radian-software/apheleia/pull/128
 [#132]: https://github.com/radian-software/apheleia/pull/132
 [#137]: https://github.com/radian-software/apheleia/pull/137
+[#143]: https://github.com/radian-software/apheleia/pull/143
 
 ## 3.0 (released 2022-06-01)
 ### Breaking changes

README.md

@@ -196,6 +196,9 @@ The following user options are also available:
   programming algorithm for point alignment. This cannot be too big or
   Emacs will hang noticeably on large reformatting operations, since
   the DP algorithm is quadratic-time.
+* `apheleia-mode-lighter`: `apheleia-mode` lighter displayed in the
+  mode-line. If you don't want to display it, use nil. Otherwise, its
+  value must be a string.
 
 Apheleia exposes some hooks for advanced customization:
 

apheleia.el

@@ -86,6 +86,12 @@ compatible with this option and formatters relying on them will crash."
                  (const :tag "Run the formatter on the remote machine" remote)
                  (const :tag "Disable formatting for remote buffers" cancel)))
 
+(defcustom apheleia-mode-lighter " Apheleia"
+  "Lighter for `apheleia-mode'."
+  :type '(choice :tag "Lighter" (const :tag "No lighter" nil) string)
+  :risky t
+  :group 'apheleia)
+
 (cl-defun apheleia--edit-distance-table (s1 s2)
   "Align strings S1 and S2 for minimum edit distance.
 Return the dynamic programming table as has table which maps cons
@@ -1356,7 +1362,7 @@ operating, to prevent an infinite loop.")
     "Minor mode for reformatting code on save without moving point.
 It is customized by means of the variables `apheleia-mode-alist'
 and `apheleia-formatters'."
-    :lighter " Apheleia"
+    :lighter apheleia-mode-lighter
     (if apheleia-mode
         (add-hook 'after-save-hook #'apheleia--format-after-save nil 'local)
       (remove-hook 'after-save-hook #'apheleia--format-after-save 'local)))