#+BABEL: :cache yes
#+LATEX_HEADER: \usepackage{parskip}
#+LATEX_HEADER: \usepackage{inconsolata}
#+PROPERTY: header-args :tangle yes :comments org

#+TITLE: Emacs configuration file
#+AUTHOR: Lars Tveito

* About

  This is an Emacs configuration file written in [[http://orgmode.org][Org mode]]. It is an attempt
  to keep my =~/.emacs.d= tidy, but still be able to keep it all in one
  file. I aim to briefly explain all my configurations as I go along!

  I would not recommend using this configuration /as-is/, because it
  probably contains a lot you don't really need. I do, however, hope people
  find some golden nuggets that they can smuggle into their own configs.

  If you really do want to try this config out, this is how I'd go about it:

  *Clone the repo.*
  #+BEGIN_SRC sh :tangle no
    git clone https://github.com/larstvei/dot-emacs
  #+END_SRC

  *Backup your old =~/.emacs.d= (if necessary).*
  #+BEGIN_SRC sh :tangle no
    mv ~/.emacs.d ~/.emacs.d-bak
  #+END_SRC

  *Backup your old =~/.emacs=-file (if necessary).*
  #+BEGIN_SRC sh :tangle no
    mv ~/.emacs ~/.emacs-bak
  #+END_SRC

  *And finally*
  #+BEGIN_SRC sh :tangle no
    mv dot-emacs ~/.emacs.d
  #+END_SRC

  On first run it should install a bunch of packages (this might take a
  while), and you might have to restart your Emacs the first time. If you
  experience bugs, please let me know!

* Configurations
** Meta

   Emacs can only load =.el=-files. We can use =C-c C-v t= to run
   =org-babel-tangle=, which extracts the code blocks from the current file
   into a source-specific file (in this case a =.el=-file).

   To avoid doing this each time a change is made we can add a function to
   the =after-save-hook= ensuring to always tangle and byte-compile the
   =org=-document after changes.

   #+BEGIN_SRC emacs-lisp
     (defun tangle-init ()
       "If the current buffer is 'init.org' the code-blocks are
     tangled, and the tangled file is compiled."
       (when (equal (buffer-file-name)
                    (expand-file-name (concat user-emacs-directory "init.org")))
         ;; Avoid running hooks when tangling.
         (let ((prog-mode-hook nil))
           (org-babel-tangle)
           (byte-compile-file (concat user-emacs-directory "init.el")))))

     (add-hook 'after-save-hook 'tangle-init)
   #+END_SRC

** Package

   Managing extensions for Emacs is simplified using =package= which is
   built in to Emacs 24 and newer. To load downloaded packages we need to
   initialize =package=. =cl= is a library that contains many functions from
   Common Lisp, and comes in handy quite often, so we want to make sure it's
   loaded, along with =package=, which is obviously needed.

   #+BEGIN_SRC emacs-lisp
     (require 'cl)
     (require 'package)
     (setq package-enable-at-startup nil)
     (package-initialize)
   #+END_SRC

   Packages can be fetched from different mirrors, [[http://melpa.milkbox.net/#/][melpa]] is the largest
   archive and is well maintained.

   #+BEGIN_SRC emacs-lisp
     (setq package-archives
           '(("gnu" . "http://elpa.gnu.org/packages/")
             ("org" . "http://orgmode.org/elpa/")
             ("MELPA" . "http://melpa.milkbox.net/packages/")))
   #+END_SRC

   We can define a predicate that tells us whether or not the newest version
   of a package is installed.

   #+BEGIN_SRC emacs-lisp
   (defun newest-package-installed-p (package)
     "Return true if the newest available PACKAGE is installed."
     (when (package-installed-p package)
       (let* ((local-pkg-desc (or (assq package package-alist)
                                  (assq package package--builtins)))
              (newest-pkg-desc (assq package package-archive-contents)))
         (and local-pkg-desc newest-pkg-desc
              (version-list-= (package-desc-vers (cdr local-pkg-desc))
                              (package-desc-vers (cdr newest-pkg-desc)))))))
   #+END_SRC

   Let's write a function to install a package if it is not installed or
   upgrades it if a new version has been released. Here our predicate comes
   in handy.

   #+BEGIN_SRC emacs-lisp
     (defun upgrade-or-install-package (package)
       "Unless the newest available version of PACKAGE is installed
     PACKAGE is installed and the current version is deleted."
       (unless (newest-package-installed-p package)
         (let ((get-desc (if (version< emacs-version "24.4") 'cdr 'cadr))
               (pkg-desc (assq package package-alist)))
           (when pkg-desc
             (if (version< emacs-version "24.4")
                 (package-delete (symbol-name package)
                                 (package-version-join
                                  (package-desc-vers (get-desc pkg-desc))))
               (package-delete pkg-desc)))
           (and (assq package package-archive-contents)
                (package-install package)))))
   #+END_SRC

   Also, we will need a function to find all dependencies from a given package.

   #+BEGIN_SRC emacs-lisp
   (defun dependencies (package)
     "Returns a list of dependencies from a given PACKAGE."
     (let* ((pkg-desc (assq package package-alist))
            (reqs (and pkg-desc (package-desc-reqs (cdr pkg-desc)))))
       (mapcar 'car reqs)))
   #+END_SRC

   The =package-refresh-contents= function downloads archive descriptions,
   this is a major bottleneck in this configuration. To avoid this we can
   try to only check for updates once every day or so. Here are three
   variables. The first specifies how often we should check for updates. The
   second specifies whether one should update during the initialization. The
   third is a path to a file where a time-stamp is stored in order to check
   when packages were updated last.

   #+BEGIN_SRC emacs-lisp
   (defvar days-between-updates 7)
   (defvar do-package-update-on-init t)
   (defvar package-last-update-file
     (expand-file-name (concat user-emacs-directory ".package-last-update")))
   #+END_SRC

   The tricky part is figuring out when packages were last updated. Here is
   a hacky way of doing it, using [[http://www.gnu.org/software/emacs/manual/html_node/emacs/Time-Stamps.html][time-stamps]]. By adding a time-stamp to the
   a file, we can determine whether or not to do an update. After that we
   must run the =time-stamp=-function to update the time-stamp.

   #+BEGIN_SRC emacs-lisp
   (require 'time-stamp)
   ;; Open the package-last-update-file
   (with-temp-file package-last-update-file
     (if (file-exists-p package-last-update-file)
         (progn
           ;; Insert it's original content's.
           (insert-file-contents package-last-update-file)
           (let ((start (re-search-forward time-stamp-start nil t))
                 (end (re-search-forward time-stamp-end nil t)))
             (when (and start end)
               ;; Assuming we have found a time-stamp, we check determine if it's
               ;; time to update.
               (setq do-package-update-on-init
                     (<= days-between-updates
                         (days-between
                          (current-time-string)
                          (buffer-substring-no-properties start end))))
               ;; Remember to update the time-stamp.
               (when do-package-update-on-init
                 (time-stamp)))))
       ;; If no such file exists it is created with a time-stamp.
       (insert "Time-stamp: <>")
       (time-stamp)))
   #+END_SRC

   Now we can use the function above to make sure packages are installed and
   up to date. Here are some packages I find useful (some of these
   configurations are also dependent on them).

   #+BEGIN_SRC emacs-lisp
     (when (and do-package-update-on-init
                (y-or-n-p "Update all packages?"))
       (package-refresh-contents)

       (let* ((packages
               '(ac-geiser         ; Auto-complete backend for geiser
                 ac-slime          ; An auto-complete source using slime completions
                 ace-jump-mode     ; quick cursor location minor mode
                 auto-compile      ; automatically compile Emacs Lisp libraries
                 auto-complete     ; auto completion
                 centered-window   ; Center the text when there's only one window
                 elscreen          ; window session manager
                 expand-region     ; Increase selected region by semantic units
                 flx-ido           ; flx integration for ido
                 idle-require      ; load elisp libraries while Emacs is idle
                 ido-vertical-mode ; Makes ido-mode display vertically.
                 geiser            ; GNU Emacs and Scheme talk to each other
                 haskell-mode      ; A Haskell editing mode
                 jedi              ; Python auto-completion for Emacs
                 js2-mode          ; Improved JavaScript editing mode
                 magit             ; control Git from Emacs
                 markdown-mode     ; Emacs Major mode for Markdown-formatted files.
                 matlab-mode       ; MATLAB integration with Emacs.
                 monokai-theme     ; A fruity color theme for Emacs.
                 move-text         ; Move current line or region with M-up or M-down
                 multiple-cursors  ; Multiple cursors for Emacs.
                 org               ; Outline-based notes management and organizer
                 paredit           ; minor mode for editing parentheses
                 powerline         ; Rewrite of Powerline
                 pretty-lambdada   ; the word `lambda' as the Greek letter.
                 slime             ; Superior Lisp Interaction Mode for Emacs
                 smex              ; M-x interface with Ido-style fuzzy matching.
                 undo-tree))       ; Treat undo history as a tree
              ;; Fetch dependencies from all packages.
              (reqs (mapcar 'dependencies packages))
              ;; Append these to the original list, and remove any duplicates.
              (packages (delete-dups (apply 'append packages reqs))))

         (dolist (package packages)
           (upgrade-or-install-package package)))

       ;; This package is only relevant for Mac OS X.
       (when (memq window-system '(mac ns))
         (upgrade-or-install-package 'exec-path-from-shell))
       (package-initialize))
   #+END_SRC

** Mac OS X

   I run this configuration mostly on Mac OS X, so we need a couple of
   settings to make things work smoothly. In the package section
   =exec-path-from-shell= is included (only if you're running OS X), this is
   to include environment-variables from the shell. It makes useing Emacs
   along with external processes a lot simpler. I also prefer using the
   =Command=-key as the =Meta=-key.

   #+BEGIN_SRC emacs-lisp
     (when (memq window-system '(mac ns))
       (setq mac-option-modifier nil
             mac-command-modifier 'meta
             x-select-enable-clipboard t)
       (exec-path-from-shell-initialize))
   #+END_SRC

** Require

   Some features are not loaded by default to minimize initialization time,
   so they have to be required (or loaded, if you will). =require=-calls
   tends to lead to the largest bottleneck's in a
   configuration. =idle-require= delays the =require=-calls to a time where
   Emacs is in idle. So this is great for stuff you eventually want to load,
   but is not a high priority.

   #+BEGIN_SRC emacs-lisp
     (require 'idle-require)             ; Need in order to use idle-require
     (require 'auto-complete-config)     ; a configuration for auto-complete-mode

     (dolist (feature
              '(auto-compile             ; auto-compile .el files
                jedi                     ; auto-completion for python
                matlab                   ; matlab-mode
                ob-matlab                ; org-babel matlab
                ox-latex                 ; the latex-exporter (from org)
                ox-md                    ; Markdown exporter (from org)
                pretty-lambdada          ; show 'lambda' as the greek letter.
                recentf                  ; recently opened files
                smex                     ; M-x interface Ido-style.
                tex-mode))               ; TeX, LaTeX, and SliTeX mode commands
       (idle-require feature))

     (setq idle-require-idle-delay 5)
     (idle-require-mode 1)
   #+END_SRC

** Sane defaults

   These are what /I/ consider to be saner defaults.

   We can set variables to whatever value we'd like using =setq=.

   #+BEGIN_SRC emacs-lisp
     (setq default-input-method "TeX"    ; Use TeX when toggling input method.
           doc-view-continuous t         ; At page edge goto next/previous.
           echo-keystrokes 0.1           ; Show keystrokes asap.
           inhibit-startup-message t     ; No splash screen please.
           initial-scratch-message nil   ; Clean scratch buffer.
           ring-bell-function 'ignore    ; Quiet.
           ;; Save undo history between sessions, if you have an undo-dir
           undo-tree-auto-save-history
           (file-exists-p
            (concat user-emacs-directory "undo"))
           undo-tree-history-directory-alist
           ;; Put undo-history files in a directory, if it exists.
           (let ((undo-dir (concat user-emacs-directory "undo")))
             (and (file-exists-p undo-dir)
                  (list (cons "." undo-dir)))))

     ;; Some mac-bindings interfere with Emacs bindings.
     (when (boundp 'mac-pass-command-to-system)
       (setq mac-pass-command-to-system nil))

   #+END_SRC

   Some variables are buffer-local, so changing them using =setq= will only
   change them in a single buffer. Using =setq-default= we change the
   buffer-local variable's default value.

   #+BEGIN_SRC emacs-lisp
   (setq-default fill-column 76                    ; Maximum line width.
                 indent-tabs-mode nil              ; Use spaces instead of tabs.
                 split-width-threshold 100         ; Split verticly by default.
                 auto-fill-function 'do-auto-fill) ; Auto-fill-mode everywhere.
   #+END_SRC

   The =load-path= specifies where Emacs should look for =.el=-files (or
   Emacs lisp files). I have a directory called =site-lisp= where I keep all
   extensions that have been installed manually (these are mostly my own
   projects).

   #+BEGIN_SRC emacs-lisp
     (let ((default-directory (concat user-emacs-directory "site-lisp/")))
       (when (file-exists-p default-directory)
         (normal-top-level-add-to-load-path '("."))
         (normal-top-level-add-subdirs-to-load-path)))
   #+END_SRC

   Answering /yes/ and /no/ to each question from Emacs can be tedious, a
   single /y/ or /n/ will suffice.

   #+BEGIN_SRC emacs-lisp
   (fset 'yes-or-no-p 'y-or-n-p)
   #+END_SRC

   To avoid file system clutter we put all auto saved files in a single
   directory.

   #+BEGIN_SRC emacs-lisp
   (defvar emacs-autosave-directory
     (concat user-emacs-directory "autosaves/")
     "This variable dictates where to put auto saves. It is set to a
     directory called autosaves located wherever your .emacs.d/ is
     located.")

   ;; Sets all files to be backed up and auto saved in a single directory.
   (setq backup-directory-alist
         `((".*" . ,emacs-autosave-directory))
         auto-save-file-name-transforms
         `((".*" ,emacs-autosave-directory t)))
   #+END_SRC

   Set =utf-8= as preferred coding system.

   #+BEGIN_SRC emacs-lisp
   (set-language-environment "UTF-8")
   #+END_SRC

   By default the =narrow-to-region= command is disabled and issues a
   warning, because it might confuse new users. I find it useful sometimes,
   and don't want to be warned.

   #+BEGIN_SRC emacs-lisp
   (put 'narrow-to-region 'disabled nil)
   #+END_SRC

   Call =auto-complete= default configuration, which enables =auto-complete=
   globally.

   #+BEGIN_SRC emacs-lisp
     (eval-after-load 'auto-complete-config `(ac-config-default))
   #+END_SRC

   Automaticly revert =doc-view=-buffers when the file changes on disk.

   #+BEGIN_SRC emacs-lisp
   (add-hook 'doc-view-mode-hook 'auto-revert-mode)
   #+END_SRC

** Modes

   There are some modes that are enabled by default that I don't find
   particularly useful. We create a list of these modes, and disable all of
   these.

   #+BEGIN_SRC emacs-lisp
   (dolist (mode
            '(tool-bar-mode                ; No toolbars, more room for text.
              scroll-bar-mode              ; No scroll bars either.
              blink-cursor-mode))          ; The blinking cursor gets old.
     (funcall mode 0))
   #+END_SRC

   Let's apply the same technique for enabling modes that are disabled by
   default.

   #+BEGIN_SRC emacs-lisp
     (dolist (mode
              '(abbrev-mode                ; E.g. sopl -> System.out.println.
                column-number-mode         ; Show column number in mode line.
                delete-selection-mode      ; Replace selected text.
                dirtrack-mode              ; directory tracking in *shell*
                recentf-mode               ; Recently opened files.
                show-paren-mode            ; Highlight matching parentheses.
                global-undo-tree-mode))    ; Undo as a tree.
       (funcall mode 1))

     (when (version< emacs-version "24.4")
       (eval-after-load 'auto-compile
         '((auto-compile-on-save-mode 1))))  ; compile .el files on save.

   #+END_SRC

   This makes =.md=-files open in =markdown-mode=.

   #+BEGIN_SRC emacs-lisp
     (add-to-list 'auto-mode-alist '("\\.md\\'" . markdown-mode))
   #+END_SRC

** Visual

   Change the color-theme to =monokai= (downloaded using =package=).

   #+BEGIN_SRC emacs-lisp
     (load-theme 'monokai t)
   #+END_SRC

   Use the [[http://www.levien.com/type/myfonts/inconsolata.html][Inconsolata]] font if it's installed on the system.

   #+BEGIN_SRC emacs-lisp
     (when (member "Inconsolata-g" (font-family-list))
       (set-face-attribute 'default nil :font "Inconsolata-g-11"))

   #+END_SRC

   # [[https://github.com/milkypostman/powerline][Powerline]] is an extension to customize the mode line. This is modified
   # version =powerline-nano-theme=. 

   # #+BEGIN_SRC emacs-lisp
   # (setq-default
   #  mode-line-format
   #  '("%e"
   #    (:eval
   #     (let* ((active (powerline-selected-window-active))
   #            ;; left hand side displays Read only or Modified.
   #            (lhs (list (powerline-raw
   #                        (cond (buffer-read-only "Read only")
   #                              ((buffer-modified-p) "Modified")
   #                              (t "")) nil 'l)))
   #            ;; right side hand displays (line,column).
   #            (rhs (list
   #                  (powerline-raw
   #                   (concat
   #                    "(" (number-to-string (line-number-at-pos))
   #                    "," (number-to-string (current-column)) ")") nil 'r)))
   #            ;; center displays buffer name.
   #            (center (list (powerline-raw "%b" nil))))
   #       (concat (powerline-render lhs)
   #               (powerline-fill-center nil (/ (powerline-width center) 2.0))
   #               (powerline-render center)
   #               (powerline-fill nil (powerline-width rhs))
   #               (powerline-render rhs))))))
   # #+END_SRC

   # This is what it looks like:
   
   # [[./powerline.png]]

** Ido

   Interactive do (or =ido-mode=) changes the way you switch buffers and
   open files/directories. Instead of writing complete file paths and buffer
   names you can write a part of it and select one from a list of
   possibilities. Using =ido-vertical-mode= changes the way possibilities
   are displayed, and =flx-ido-mode= enables fuzzy matching.

   #+BEGIN_SRC emacs-lisp
   (dolist (mode
            '(ido-mode                   ; Interactivly do.
              ido-everywhere             ; Use Ido for all buffer/file reading.
              ido-vertical-mode          ; Makes ido-mode display vertically.
              flx-ido-mode))             ; Toggle flx ido mode.
     (funcall mode 1))
   #+END_SRC

   We can set the order of file selections in =ido=. I prioritize source
   files along with =org=- and =tex=-files.

   #+BEGIN_SRC emacs-lisp
   (setq ido-file-extensions-order
         '(".el" ".scm" ".lisp" ".java" ".c" ".h" ".org" ".tex"))
   #+END_SRC

   Sometimes when using =ido-switch-buffer= the =*Messages*= buffer get in
   the way, so we set it to be ignored (it can be accessed using =C-h e=, so
   there is really no need for it in the buffer list).

   #+BEGIN_SRC emacs-lisp
   (add-to-list 'ido-ignore-buffers "*Messages*")
   #+END_SRC

   To make =M-x= behave more like =ido-mode= we can use the =smex=
   package. It needs to be initialized, and we can replace the binding to
   the standard =execute-extended-command= with =smex=.

   #+BEGIN_SRC emacs-lisp
     (smex-initialize)
   #+END_SRC

** Calendar

   Define a function to display week numbers in =calender-mode=. The snippet
   is from [[http://www.emacswiki.org/emacs/CalendarWeekNumbers][EmacsWiki]].

   #+BEGIN_SRC emacs-lisp
   (defun calendar-show-week (arg)
     "Displaying week number in calendar-mode."
     (interactive "P")
     (copy-face font-lock-constant-face 'calendar-iso-week-face)
     (set-face-attribute
      'calendar-iso-week-face nil :height 0.7)
     (setq calendar-intermonth-text
           (and arg
                '(propertize
                  (format
                   "%2d"
                   (car (calendar-iso-from-absolute
                         (calendar-absolute-from-gregorian
                          (list month day year)))))
                  'font-lock-face 'calendar-iso-week-face))))
   #+END_SRC

   Evaluate the =calendar-show-week= function.

   #+BEGIN_SRC emacs-lisp
   (calendar-show-week t)
   #+END_SRC

   Set Monday as the first day of the week, and set my location.

   #+BEGIN_SRC emacs-lisp
   (setq calendar-week-start-day 1
         calendar-latitude 60.0
         calendar-longitude 10.7
         calendar-location-name "Oslo, Norway")
   #+END_SRC

** Mail

   I use [[http://www.djcbsoftware.nl/code/mu/mu4e.html][mu4e]] (which is a part of [[http://www.djcbsoftware.nl/code/mu/][mu]]) along with [[http://docs.offlineimap.org/en/latest/][offlineimap]] on one of my
   computers. Because the mail-setup wont work without these programs
   installed we bind =load-mail-setup= to =nil=. If the value is changed to
   a =non-nil= value mail is setup.

   #+BEGIN_SRC emacs-lisp
     (defvar load-mail-setup nil)

     (when load-mail-setup
       (eval-after-load 'mu4e
         '(progn
            ;; Some basic mu4e settings.
            (setq mu4e-maildir           "~/.ifimail"     ; top-level Maildir
                  mu4e-sent-folder       "/INBOX.Sent"    ; folder for sent messages
                  mu4e-drafts-folder     "/INBOX.Drafts"  ; unfinished messages
                  mu4e-trash-folder      "/INBOX.Trash"   ; trashed messages
                  mu4e-refile-folder     "/INBOX.Archive" ; saved messages
                  mu4e-get-mail-command  "offlineimap"    ; offlineimap to fetch mail
                  mu4e-compose-signature "- Lars"         ; Sign my name
                  mu4e-update-interval   (* 5 60)         ; update every 5 min
                  mu4e-confirm-quit      nil              ; just quit
                  mu4e-view-show-images  t                ; view images
                  mu4e-html2text-command
                  "html2text -utf8")                      ; use utf-8

            ;; Setup for sending mail.
            (setq user-full-name
                  "Lars Tveito"                        ; Your full name
                  user-mail-address
                  "larstvei@ifi.uio.no"                ; And email-address
                  smtpmail-smtp-server
                  "smtp.uio.no"                        ; Host to mail-server
                  smtpmail-smtp-service 465            ; Port to mail-server
                  smtpmail-stream-type 'ssl            ; Protocol used for sending
                  send-mail-function 'smtpmail-send-it ; Use smpt to send
                  mail-user-agent 'mu4e-user-agent)    ; Use mu4e!

            ;; Register file types that can be handled by ImageMagick.
            (when (fboundp 'imagemagick-register-types)
              (imagemagick-register-types))))
       (autoload 'mu4e "mu4e" nil t)
       (global-set-key (kbd "C-x m") 'mu4e))
   #+END_SRC

** Flyspell

   Flyspell offers on-the-fly spell checking. We can enable flyspell for all
   text-modes with this snippet.

   #+BEGIN_SRC emacs-lisp
   (add-hook 'text-mode-hook 'turn-on-flyspell)
   #+END_SRC

   To use flyspell for programming there is =flyspell-prog-mode=, that only
   enables spell checking for comments and strings. We can enable it for all
   programming modes using the =prog-mode-hook=. Flyspell interferes with
   auto-complete mode, but there is a workaround provided by auto complete.

   #+BEGIN_SRC emacs-lisp
     (add-hook 'prog-mode-hook 'flyspell-prog-mode)
     (eval-after-load 'auto-complete
       '(ac-flyspell-workaround))
   #+END_SRC

   When working with several languages, we should be able to cycle through
   the languages we most frequently use. Every buffer should have a separate
   cycle of languages, so that cycling in one buffer does not change the
   state in a different buffer (this problem occurs if you only have one
   global cycle). We can implement this by using a [[http://www.gnu.org/software/emacs/manual/html_node/elisp/Closures.html][closure]].

   #+BEGIN_SRC emacs-lisp
     (defun cycle-languages ()
       "Changes the ispell dictionary to the first element in
     ISPELL-LANGUAGES, and returns an interactive function that cycles
     the languages in ISPELL-LANGUAGES when invoked."
       (lexical-let ((ispell-languages '#1=("american" "norsk" . #1#)))
         (ispell-change-dictionary (car ispell-languages))
         (lambda ()
           (interactive)
           ;; Rotates the languages cycle and changes the ispell dictionary.
           (ispell-change-dictionary
            (car (setq ispell-languages (cdr ispell-languages)))))))
   #+END_SRC

   =Flyspell= signals an error if there is no spell-checking tool is
   installed. We can advice =turn-on-flyspell= and =flyspell-prog-mode= to
   only try to enable =flyspell= if a spell-checking tool is available. Also
   we want to enable cycling the languages by typing =C-c l=, so we bind the
   function returned from =cycle-languages=.

   #+BEGIN_SRC emacs-lisp
     (defadvice turn-on-flyspell (before check nil activate)
       "Turns on flyspell only if a spell-checking tool is installed."
       (when (executable-find ispell-program-name)
         (local-set-key (kbd "C-c l") (cycle-languages))))
   #+END_SRC

   #+BEGIN_SRC emacs-lisp
     (defadvice flyspell-prog-mode (before check nil activate)
       "Turns on flyspell only if a spell-checking tool is installed."
       (when (executable-find ispell-program-name)
         (local-set-key (kbd "C-c l") (cycle-languages))))
   #+END_SRC

** Org

   I use =org-agenda= for appointments and such.

   #+BEGIN_SRC emacs-lisp
   (setq org-agenda-start-on-weekday nil              ; Show agenda from today.
         org-agenda-files '("~/Dropbox/life.org")     ; A list of agenda files.
         org-agenda-default-appointment-duration 120) ; 2 hours appointments.
   #+END_SRC

   When editing org-files with source-blocks, we want the source blocks to
   be themed as they would in their native mode.

   #+BEGIN_SRC emacs-lisp
     (setq org-src-fontify-natively t
           org-confirm-babel-evaluate nil)

   #+END_SRC

   This is quite an ugly fix for allowing code markup for expressions like
   ="this string"=, because the quotation marks causes problems.

   #+BEGIN_SRC emacs-lisp
     (require 'org)
     (setcar (nthcdr 2 org-emphasis-regexp-components) " \t\n,")
     (custom-set-variables `(org-emphasis-alist ',org-emphasis-alist))
   #+END_SRC

** Interactive functions
   <<sec:defuns>>

   To search recent files useing =ido-mode= we add this snippet from
   [[http://www.emacswiki.org/emacs/CalendarWeekNumbers][EmacsWiki]].

   #+BEGIN_SRC emacs-lisp
   (defun recentf-ido-find-file ()
     "Find a recent file using Ido."
     (interactive)
     (let ((f (ido-completing-read "Choose recent file: " recentf-list nil t)))
       (when f
         (find-file f))))
   #+END_SRC

   =just-one-space= removes all whitespace around a point - giving it a
   negative argument it removes newlines as well. We wrap a interactive
   function around it to be able to bind it to a key. In Emacs 24.4
   =cycle-spacing= was introduced, and it works like just one space, but
   when run in succession it cycles between one, zero and the original
   number of spaces.

   #+BEGIN_SRC emacs-lisp
     (defun cycle-spacing-delete-newlines ()
       "Removes whitespace before and after the point."
       (interactive)
       (if (version< emacs-version "24.4")
           (just-one-space -1)
         (cycle-spacing -1)))
   #+END_SRC

   #+BEGIN_SRC emacs-lisp
     (defun jump-to-symbol-internal (symbol forwardp)
       (let* ((point (point))
              (thing (prin1-to-string symbol))
              (beg (and (not forwardp) thing (beginning-of-thing 'symbol)))
              (end (and forwardp thing (end-of-thing 'symbol)))
              (diff (and thing (if forwardp (- point end) (- point beg)))))
         (if (and thing
                  (funcall (if forwardp
                               'search-forward 'search-backward) thing nil t)
                  (eq (intern thing) symbol))
             (forward-char diff)
           (goto-char point))))

     (defun jump-to-symbol-backward ()
       (interactive)
       (jump-to-symbol-internal (symbol-at-point) nil))

     (defun jump-to-symbol-forward ()
       (interactive)
       (jump-to-symbol-internal (symbol-at-point) t))
   #+END_SRC

   I sometimes regret killing the =*scratch*=-buffer, and have realized I
   never want to actually kill it. I just want to get it out of the way, and
   clean it up. The function below does just this for the
   =*scratch*=-buffer, and works like =kill-this-buffer= for any other
   buffer. It removes all buffer content and buries the buffer (this means
   making it the least likely candidate for =other-buffer=).

   #+BEGIN_SRC emacs-lisp
     (defun kill-this-buffer-unless-scratch ()
       "Works like `kill-this-buffer' unless the current buffer is the
     ,*scratch* buffer. In witch case the buffer content is deleted and
     the buffer is buried."
       (interactive)
       (if (not (string= (buffer-name) "*scratch*"))
           (kill-this-buffer)
         (delete-region (point-min) (point-max))
         (switch-to-buffer (other-buffer))
         (bury-buffer "*scratch*")))
   #+END_SRC

   To duplicate either selected text or a line we define this interactive
   function.

   #+BEGIN_SRC emacs-lisp
     (defun duplicate-thing ()
       "Duplicates the current line, or the region if active."
       (interactive)
       (save-excursion
         (let ((start (if (region-active-p) (region-beginning) (point-at-bol)))
               (end   (if (region-active-p) (region-end) (point-at-eol))))
           (goto-char end)
           (unless (region-active-p)
             (newline))
           (insert (buffer-substring start end)))))
   #+END_SRC

   To tidy up a buffer we define this function borrowed from [[https://github.com/simenheg][simenheg]].

   #+BEGIN_SRC emacs-lisp
   (defun tidy ()
     "Ident, untabify and unwhitespacify current buffer, or region if active."
     (interactive)
     (let ((beg (if (region-active-p) (region-beginning) (point-min)))
           (end (if (region-active-p) (region-end) (point-max))))
       (indent-region beg end)
       (whitespace-cleanup)
       (untabify beg (if (< end (point-max)) end (point-max)))))
   #+END_SRC

   If you have a link to a raw =.el=-file, run =M-x try= and yank an URL
   into the minibuffer, and the file will be evaluated.

   #+BEGIN_SRC emacs-lisp
     (defun try (url)
       "Takes an URL to a .el-file, and evaluates it."
       (interactive (list (read-from-minibuffer "url: ")))
       (with-current-buffer (url-retrieve-synchronously url)
         (eval-region (search-forward-regexp "^$") (point-max))))
   #+END_SRC

** Advice

   An advice can be given to a function to make it behave differently. This
   advice makes =eval-last-sexp= (bound to =C-x C-e=) replace the sexp with
   the value.

   #+BEGIN_SRC emacs-lisp
   (defadvice eval-last-sexp (around replace-sexp (arg) activate)
     "Replace sexp when called with a prefix argument."
     (if arg
         (let ((pos (point)))
           ad-do-it
           (goto-char pos)
           (backward-kill-sexp)
           (forward-sexp))
       ad-do-it))
   #+END_SRC

   When interactively changing the theme (using =M-x load-theme=), the
   current custom theme is not disabled. This often gives weird-looking
   results; we can advice =load-theme= to always disable themes currently
   enabled themes. 

   #+BEGIN_SRC emacs-lisp
     (defadvice load-theme
       (before disable-before-load (theme &optional no-confirm no-enable) activate) 
       (mapc 'disable-theme custom-enabled-themes))
   #+END_SRC

** Presentation-mode

   When giving talks it's nice to be able to scale the text
   globally. =text-scale-mode= works great for a single buffer, this advice
   makes this work globally.

   #+BEGIN_SRC emacs-lisp
     (defadvice text-scale-mode (around all-buffers (arg) activate)
       (if (not global-text-scale-mode)
           ad-do-it
         (setq-default text-scale-mode-amount text-scale-mode-amount)
         (dolist (buffer (buffer-list))
           (with-current-buffer buffer
             ad-do-it))))
   #+END_SRC

   We don't want this to be default behavior, so we can make a global mode
   from the =text-scale-mode=, using =define-globalized-minor-mode=.

   #+BEGIN_SRC emacs-lisp
     (require 'face-remap)

     (define-globalized-minor-mode
       global-text-scale-mode
       text-scale-mode
       (lambda () (text-scale-mode 1)))
   #+END_SRC

* Mode specific
** Shell

   I use =shell= whenever i want to use access the command line in Emacs. I
   keep a symlink between my =~/.bash_profile= (because I run OS X) and
   =~/.emacs_bash=, to make the transition between my standard terminal and
   the shell as small as possible. To be able to quickly switch back and
   forth between a shell I make use of this little function.
   
   #+BEGIN_SRC emacs-lisp
   (defun toggle-shell ()
     "Jumps to eshell or back."
     (interactive)
     (if (string= (buffer-name) "*shell*")
         (switch-to-prev-buffer)
       (shell)))
   #+END_SRC

   I'd like the =C-l= to work more like the standard terminal (which works
   like running =clear=), and resolve this by simply removing the
   buffer-content. Mind that this is not how =clear= works, it simply adds a
   bunch of newlines, and puts the prompt at the top of the window, so it
   does not remove anything. In Emacs removing stuff is less of a worry,
   since we can always undo!

   #+BEGIN_SRC emacs-lisp
     (defun clear-shell ()
       "Runs `comint-truncate-buffer' with the
     `comint-buffer-maximum-size' set to zero."
       (interactive)
       (let ((comint-buffer-maximum-size 0))
        (comint-truncate-buffer)))
   #+END_SRC
   
   Lastly we should bind our functions. The =toggle-shell= should be a
   global binding (because we want to be able to switch to a shell from any
   buffer), but the =clear-shell= should only affect =shell-mode=.

   #+BEGIN_SRC emacs-lisp
     (add-hook 'shell-mode-hook (lambda () (local-set-key (kbd "C-l") 'clear-shell)))
   #+END_SRC

** Lisp

   =Pretty-lambda= provides a customizable variable
   =pretty-lambda-auto-modes= that is a list of common lisp modes. Here we
   can add some extra lisp-modes. We run the =pretty-lambda-for-modes=
   function to activate =pretty-lambda-mode= in lisp modes.

   #+BEGIN_SRC emacs-lisp
     (dolist (mode '(slime-repl-mode geiser-repl-mode ielm-mode clojure-mode
                                     cider-repl-mode))
       (add-to-list 'pretty-lambda-auto-modes mode))

     (pretty-lambda-for-modes)
   #+END_SRC

   I use =Paredit= when editing lisp code, we enable this for all lisp-modes
   in the =pretty-lambda-auto-modes= list.

   #+BEGIN_SRC emacs-lisp
   (dolist (mode pretty-lambda-auto-modes)
     ;; add paredit-mode to all mode-hooks
     (add-hook (intern (concat (symbol-name mode) "-hook")) 'paredit-mode))
   #+END_SRC

*** Emacs Lisp

    In =emacs-lisp-mode= we can enable =eldoc-mode= to display information
    about a function or a variable in the echo area.

    #+BEGIN_SRC emacs-lisp
    (add-hook 'emacs-lisp-mode-hook 'turn-on-eldoc-mode)
    (add-hook 'lisp-interaction-mode-hook 'turn-on-eldoc-mode)
    #+END_SRC

*** Common lisp

    I use [[http://www.common-lisp.net/project/slime/][Slime]] along with =lisp-mode= to edit Common Lisp code. Slime
    provides code evaluation and other great features, a must have for a
    Common Lisp developer. [[http://www.quicklisp.org/beta/][Quicklisp]] is a library manager for Common Lisp,
    and you can install Slime following the instructions from the site along
    with this snippet.

    #+BEGIN_SRC emacs-lisp
    (when (file-exists-p "~/.quicklisp/slime-helper.el")
      (load (expand-file-name "~/.quicklisp/slime-helper.el")))
    #+END_SRC

    We can specify what Common Lisp program Slime should use (I use SBCL).

    #+BEGIN_SRC emacs-lisp
    (setq inferior-lisp-program "sbcl")
    #+END_SRC

    To improve auto completion for Common Lisp editing we can use =ac-slime=
    which uses slime completions as a source.

    #+BEGIN_SRC emacs-lisp
    (add-hook 'slime-mode-hook 'set-up-slime-ac)
    (add-hook 'slime-repl-mode-hook 'set-up-slime-ac)

    (eval-after-load "auto-complete"
      '(add-to-list 'ac-modes 'slime-repl-mode))
    #+END_SRC

    More sensible =loop= indentation, borrowed from [[https://github.com/simenheg][simenheg]].

    #+BEGIN_SRC emacs-lisp
      (setq lisp-loop-forms-indentation   2
            lisp-simple-loop-indentation  2
            lisp-loop-keyword-indentation 6)
    #+END_SRC

*** Scheme

    [[http://www.nongnu.org/geiser/][Geiser]] provides features similar to Slime for Scheme editing. Everything
    works pretty much out of the box, we only need to add auto completion,
    and specify which scheme-interpreter we prefer.

   #+BEGIN_SRC emacs-lisp
     (add-hook 'geiser-mode-hook 'ac-geiser-setup)
     (add-hook 'geiser-repl-mode-hook 'ac-geiser-setup)
     (eval-after-load "auto-complete"
       '(add-to-list 'ac-modes 'geiser-repl-mode))
     (eval-after-load "geiser"
       '(add-to-list 'geiser-active-implementations 'plt-r5rs)) ;'(racket))
   #+END_SRC

** Java and C

   The =c-mode-common-hook= is a general hook that work on all C-like
   languages (C, C++, Java, etc...). I like being able to quickly compile
   using =C-c C-c= (instead of =M-x compile=), a habit from =latex-mode=.

   #+BEGIN_SRC emacs-lisp
   (defun c-setup ()
     (local-set-key (kbd "C-c C-c") 'compile))

   (add-hook 'c-mode-common-hook 'c-setup)
   #+END_SRC

   Some statements in Java appear often, and become tedious to write
   out. We can use abbrevs to speed this up.

   #+BEGIN_SRC emacs-lisp
   (define-abbrev-table 'java-mode-abbrev-table
     '(("psv" "public static void main(String[] args) {" nil 0)
       ("sopl" "System.out.println" nil 0)
       ("sop" "System.out.printf" nil 0)))
   #+END_SRC

   To be able to use the abbrev table defined above, =abbrev-mode= must be
   activated.

   #+BEGIN_SRC emacs-lisp
   (defun java-setup ()
     (abbrev-mode t)
     (setq-local compile-command (concat "javac " (buffer-name))))

   (add-hook 'java-mode-hook 'java-setup)
   #+END_SRC

** Assembler

   When writing assembler code I use =#= for comments. By defining
   =comment-start= we can add comments using =M-;= like in other programming
   modes. Also in assembler should one be able to compile using =C-c C-c=.

   #+BEGIN_SRC emacs-lisp
   (defun asm-setup ()
     (setq comment-start "#")
     (local-set-key (kbd "C-c C-c") 'compile))

   (add-hook 'asm-mode-hook 'asm-setup)
   #+END_SRC

** LaTeX

   =.tex=-files should be associated with =latex-mode= instead of
   =tex-mode=.

   #+BEGIN_SRC emacs-lisp
   (add-to-list 'auto-mode-alist '("\\.tex\\'" . latex-mode))
   #+END_SRC

   I like using the [[https://code.google.com/p/minted/][Minted]] package for source blocks in LaTeX. To make org
   use this we add the following snippet.

   #+BEGIN_SRC emacs-lisp
     (eval-after-load 'org
       '(add-to-list 'org-latex-packages-alist '("" "minted")))
     (setq org-latex-listings 'minted)
   #+END_SRC

   Because [[https://code.google.com/p/minted/][Minted]] uses [[http://pygments.org][Pygments]] (an external process), we must add the
   =-shell-escape= option to the =org-latex-pdf-process= commands. The
   =tex-compile-commands= variable controls the default compile command for
   Tex- and LaTeX-mode, we can add the flag with a rather dirty statement
   (if anyone finds a nicer way to do this, please let me know).

   #+BEGIN_SRC emacs-lisp
     (eval-after-load 'ox-latex
       '(setq org-latex-pdf-process
              (mapcar
               (lambda (str)
                 (concat "pdflatex -shell-escape "
                         (substring str (string-match "-" str))))
               org-latex-pdf-process)))

     (eval-after-load 'tex-mode
       '(setcar (cdr (cddaar tex-compile-commands)) " -shell-escape "))
   #+END_SRC

** Markdown

   I sometimes use a specialized markdown format, where inline math-blocks
   can be achieved by surrounding a LaTeX formula with =$math$= and
   =$/math$=. Writing these out became tedious, so I wrote a small function.

   #+BEGIN_SRC emacs-lisp
     (defun insert-markdown-inline-math-block ()
       "Inserts an empty math-block if no region is active, otherwise wrap a
     math-block around the region."
       (interactive)
       (let* ((beg (region-beginning))
              (end (region-end))
              (body (if (region-active-p) (buffer-substring beg end) "")))
         (when (region-active-p)
           (delete-region beg end))
         (insert (concat "$math$ " body " $/math$"))
         (search-backward " $/math$")))
   #+END_SRC

   Most of my writing in this markup is in Norwegian, so the dictionary is
   set accordingly. The markup is also sensitive to line breaks, so
   =auto-fill-mode= is disabled. Of course we want to bind our lovely
   function to a key!

   #+BEGIN_SRC emacs-lisp
     (add-hook 'markdown-mode-hook
               (lambda ()
                 (auto-fill-mode 0)
                 (ispell-change-dictionary "norsk")
                 (local-set-key (kbd "C-c b") 'insert-markdown-inline-math-block)) t)
   #+END_SRC

** Python

   # [[http://tkf.github.io/emacs-jedi/released/][Jedi]] offers very nice auto completion for =python-mode=. Mind that it is
   # dependent on some python programs as well, so make sure you follow the
   # instructions from the site.

   # #+BEGIN_SRC emacs-lisp
   # ;; (setq jedi:server-command
   # ;;       (cons "python3" (cdr jedi:server-command))
   # ;;       python-shell-interpreter "python3")
   # (add-hook 'python-mode-hook 'jedi:setup)
   # (setq jedi:complete-on-dot t)
   # (add-hook 'python-mode-hook 'jedi:ac-setup)
   # #+END_SRC

** Haskell

   =haskell-doc-mode= is similar to =eldoc=, it displays documentation in
   the echo area. Haskell has several indentation modes - I prefer using
   =haskell-indent=.

   #+BEGIN_SRC emacs-lisp
   (add-hook 'haskell-mode-hook 'turn-on-haskell-doc-mode)
   (add-hook 'haskell-mode-hook 'turn-on-haskell-indent)
   #+END_SRC

** Matlab

   =Matlab-mode= works pretty good out of the box, but we can do without the
   splash screen.

   #+BEGIN_SRC emacs-lisp
     (eval-after-load 'matlab
       '(add-to-list 'matlab-shell-command-switches "-nosplash"))
   #+END_SRC
* Key bindings

   Inspired by [[http://stackoverflow.com/questions/683425/globally-override-key-binding-in-emacs][this StackOverflow post]] I keep a =custom-bindings-map= that
   holds all my custom bindings. This map can be activated by toggling a
   simple =minor-mode= that does nothing more than activating the map. This
   inhibits other =major-modes= to override these bindings. I keep this at
   the end of the init-file to make sure that all functions are actually
   defined.

   #+BEGIN_SRC emacs-lisp
     (defvar custom-bindings-map (make-keymap)
       "A keymap for custom bindings.")
   #+END_SRC

   Bindings for [[https://github.com/magnars/expand-region.el][expand-region]].

   #+BEGIN_SRC emacs-lisp
   (define-key custom-bindings-map (kbd "C-'")  'er/expand-region)
   (define-key custom-bindings-map (kbd "C-;")  'er/contract-region)
   #+END_SRC

   Bindings for [[https://github.com/magnars/multiple-cursors.el][multiple-cursors]].

   #+BEGIN_SRC emacs-lisp
   (define-key custom-bindings-map (kbd "C-c e")  'mc/edit-lines)
   (define-key custom-bindings-map (kbd "C-c a")  'mc/mark-all-like-this)
   (define-key custom-bindings-map (kbd "C-c n")  'mc/mark-next-like-this)
   #+END_SRC

   Bindings for [[http://magit.github.io][Magit]].

   #+BEGIN_SRC emacs-lisp
   (define-key custom-bindings-map (kbd "C-c m") 'magit-status)
   #+END_SRC

   Bindings for [[https://github.com/winterTTr/ace-jump-mode][ace-jump-mode]].

   #+BEGIN_SRC emacs-lisp
   (define-key custom-bindings-map (kbd "C-c SPC") 'ace-jump-mode)
   #+END_SRC

   Bindings for [[http://emacs-helm.github.io/helm/][Helm]].

   #+BEGIN_SRC emacs-lisp
     (define-key custom-bindings-map (kbd "C-c h g") 'helm-google-suggest)
   #+END_SRC

   Bindings for [[https://github.com/nonsequitur/smex][smex]]. This overrides the standard =M-x=.

   #+BEGIN_SRC emacs-lisp
     (define-key custom-bindings-map (kbd "M-x") 'smex)
   #+END_SRC

   Bindings for =move-text=.

   #+BEGIN_SRC emacs-lisp
   (define-key custom-bindings-map (kbd "<M-S-up>")    'move-text-up)
   (define-key custom-bindings-map (kbd "<M-S-down>")  'move-text-down)
   #+END_SRC

   Bind some native Emacs functions.

   #+BEGIN_SRC emacs-lisp
     (define-key custom-bindings-map (kbd "C-j")      'newline-and-indent)
     (define-key custom-bindings-map (kbd "C-c s")    'ispell-word)
     (define-key custom-bindings-map (kbd "C-c t")    'org-agenda-list)
     (define-key custom-bindings-map (kbd "C-x C-r")  'recentf-ido-find-file)
   #+END_SRC

   Bind the functions defined [[sec:defuns][above]].

   #+BEGIN_SRC emacs-lisp
     (define-key custom-bindings-map (kbd "M-p")     'jump-to-symbol-backward)
     (define-key custom-bindings-map (kbd "M-n")     'jump-to-symbol-forward)
     (define-key custom-bindings-map (kbd "C-x k")   'kill-this-buffer-unless-scratch)
     (define-key custom-bindings-map (kbd "C-x t")   'toggle-shell)
     (define-key custom-bindings-map (kbd "C-c j")   'cycle-spacing-delete-newlines)
     (define-key custom-bindings-map (kbd "C-c d")   'duplicate-thing)
     (define-key custom-bindings-map (kbd "<C-tab>") 'tidy)
   #+END_SRC

   Lastly we need to activate the map by creating and activating the
   =minor-mode=.

   #+BEGIN_SRC emacs-lisp
     (define-minor-mode custom-bindings-mode
       "A mode that activates custom-bindings."
       t nil custom-bindings-map)
   #+END_SRC