dotfiles/emacs/.emacs.d/init.el

;;; init.el --- Tom-Emacs Interface                  -*- lexical-binding: t; -*-

;; Copyright (C) 2016  Tom Willemse

;; Author: Tom Willemse <tom@ryuslash.org>
;; Keywords: local

;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with this program.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; This is my personal Emacs configuration. The name was inspired by
;; "Ghost in the Shell 2: Man-Machine Interface" and Ryan Rix's
;; "Complete Computing Environment".

;;; Code:

;;;; Package configuration:
;;; Require package.el since we immediately start using its variables
;;; and functions anyway, no need to delay loading.
(require 'package)

;; Add the MELPA and org package archives because I like living on the
;; bleeding edge. This should be done both at run-time and
;; compile-time so I can install packages at compile time.
(eval-and-compile
  (add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/"))
  (add-to-list 'package-archives '("org" . "http://orgmode.org/elpa/")))

;; Initialize package.el so that packages can be loaded and used. This
;; also needs to be done at both run-time and compile-time so packages
;; can be installed at compile-time.
(eval-and-compile (package-initialize))

;; Refresh the package contents so packages can be installed from all
;; configured archives. Don't do this at run-time because it slows
;; down the process too much.
(eval-when-compile (package-refresh-contents))

;; This macro is inspired by use-package, but I want to maintain some
;; control of the syntax I use to configure my settings.
(defmacro ensure-library (library &rest args)
  "Make sure LIBRARY is installed.

ARGS should be a plist which may contain one of the following options:

- :package

  Specify which package should actually be installed to ensure
  the library named in LIBRARY exists.

- :path

  Specify a path to add to the load path to be able to load this
  package."
  (declare (indent 1))
  (let ((library-symbol (cl-gensym))
        (package-symbol (cl-gensym))
        (path-symbol (cl-gensym))
        (package (or (plist-get args :package) library))
        (path (plist-get args :path)))
    `(progn
       (eval-and-compile
         (let ((,path-symbol ,path))
           (if ,path-symbol
               (add-to-list 'load-path
                            (if (file-name-absolute-p ,path-symbol)
                                ,path-symbol
                              (concat user-emacs-directory ,path-symbol))))))
       (eval-when-compile
         (let ((,library-symbol ',library)
               (,package-symbol ',package))
           (unless (require ,library-symbol nil :noerror)
             (package-install ,package-symbol)
             (require ,library-symbol)))))))

;;;; Helper functions:

;; I have noticed that I refer to the combination of
;; `user-emacs-directory' and "data/" a lot, so I wrote this function
;; to make referencing it cleaner. Also useful if I ever want to move
;; my data directory.
(defun oni:data-location (file-name)
  "Return the location of FILE-NAME within my data directory.
This is currently the data directory under the
`user-emacs-directory'."
  (concat user-emacs-directory "data/" file-name))

(with-eval-after-load 'ert
  (ert-deftest oni:data-location ()
    "Test that `oni:data-location' returns the correct locations."
    (should (string= "~/.emacs.d/data/backup-files/"
		     (oni:data-location "backup-files/")))
    (should (string= "~/.emacs.d/data/auto-save-files/"
		     (oni:data-location "auto-save-files/")))
    (should (string= "~/.emacs.d/data/auto-save-list/.saves-"
		     (oni:data-location "auto-save-list/.saves-")))))

;;;; Backups:

;; I don't like having every directory filled with "filename~"
;; files. So instead of saving backup files to the same directory,
;; save them to a special one instead.
(setq backup-directory-alist `((".*" . ,(oni:data-location "backup-files/"))))

;;;; Auto saves:

;; I prefer to keep all autosave files in a single directory so they
;; don't clog up my filesystem so much. Usually these files get
;; deleted, but sometimes they don't, and I don't think they look
;; pretty. Add it to the end of the list because the default value
;; stores auto-saves for remote files in /tmp, which is fine by me.
(add-to-list 'auto-save-file-name-transforms
             `(".*" ,(oni:data-location "auto-save-files/") t) :append)

;; Place the files which contain the auto save files in a similar
;; directory.
(setq auto-save-list-file-prefix (oni:data-location "auto-save-list/.saves-"))

;;;; Tabs:
;; Generally I prefer using spaces over tabs. Especially for lisp-like
;; languages.
(setq-default indent-tabs-mode nil)

;; A tab-width of 8 is too wide for me, and 2 is too narrow. 4 is just
;; right.
(setq-default tab-width 4)

;;;; Font:

(defvar oni:preferred-font "Fantasque Sans Mono-13"
  "My personally preferred font.")

;; This sets the font for normal Emacs sessions. This will change the
;; font for all _existing_ frames, any future frames will not be
;; affected by this.
(set-frame-font oni:preferred-font nil t)

;; This sets the font for Emacs daemon-mode sessions. This changes the
;; font for all _future_ frames, but doesn't change anything for the
;; currently existing frames.
(add-to-list 'default-frame-alist `(font . ,oni:preferred-font))

;;;; Menu bar:

;; I don't use the menu bar, so it just takes up space.
(menu-bar-mode -1)

;;;; Tool bar:

;; I don't use the tool bar, so it just takes up space.
(tool-bar-mode -1)

;;;; Scroll bar:
;; I don't use the scroll bar to either navigate my buffers or see
;; whereabouts I am, so they just take up space.
(scroll-bar-mode -1)

;;;; Whitespace:
;; I hate it when trailing whitespace is left around a file. I've been
;; using this for years, and apart from having some trouble working
;; with people who don't pay attention to it, it has worked
;; flawlessly.
(ensure-library destroy-trailing-whitespace
  :path "vendor-lisp/destroy-trailing-whitespace")
(require 'destroy-trailing-whitespace)
(global-destroy-trailing-whitespace-mode)

;; Having a final newline at the end of the file is always a good
;; idea. Some programs just don't work without it and others produce
;; some strange results. Github diffs are an example.
(setq require-final-newline t)

;;;; Minor modes:

;;;;; Paredit:

(ensure-package paredit)

;;;; Major modes:

;;;;; Scheme mode:

(add-hook 'scheme-mode-hook 'paredit-mode)

;;;; Applications:

;;;;; Magit:

(ensure-package magit)

(provide 'init)
;;; init.el ends here