My personal emacs configuration, hopefully in a sharable state.
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eigengrau Merge branch 'master' of github.com:jackrusher/dotemacs Mar 16, 2018
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README.md

WHY?

After the release of emacs 24.1, I took the time to jettison an enormous quantity of elisp that had accumulated in my dotfiles since 1985. Most of the custom features implemented by that code now have analogues in the base emacs or in one of the many excellent packages available via the ELPA-compatible repositories.

INSTALLATION

If you would like to test out this configuration, clone this repo and place it in your home directory as the directory .emacs.d.

I install emacs on Mac OS X using homebrew. Note that the current formula has been updated to install Emacs 25 and the git history no longer includes the commit for 24.5. Until this configuration is made compatibly with it, you'll need to update the formula to install 24.5 by copying /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/emacs.rb and updating the url and sha256 to:

  url "https://ftp.gnu.org/gnu/emacs/emacs-24.5.tar.xz"
  sha256 "dd47d71dd2a526cf6b47cb49af793ec2e26af69a0951cc40e43ae290eacfc34e"

Then install it:

$ brew install emacs --with-gnutls --with-cocoa ./emacs.rb

Once this is complete, you should also install the Aspell spell checker, required by Flyspell:

$ brew install aspell --with-lang-en

And The Silver Searcher, required by ag:

$ brew install ag

CUSTOMIZATION

If you would like to extend this configuration, create a <username>-local.el file within your .emacs.d/lisp directory and that file will be loaded after this configuration has been initialized.

A PRIMER

One of the goals of this configuration is to avoid the cognitive load of switching keyboard habits between applications. Luckily, many of the default emacs control sequences are also supported by OSX text editing panels and the major shells (and can be made more comformant via one's inputrc).

The usual OSX command key bindings are mostly supported. Command-S saves, Command-F "finds" (searches forward), cut and paste, selection, and so on all operate normally. Some commands are modified so that they're the emacs semantic equivalent of their OS X counterparts. For example, Command-w "kills" (closes) the current buffer rather than the window (which should be full-screen most of the time).

The emacs notation for key sequences looks like a (press a), C-c (control + c), M-x ("meta ex", where "meta" is the alt/option key in this configuration) or s-a ("super a", where "super" is the command key). So, a sequence like C-x C-f means "hold down the control key while pressing first 'x' then 'f'.

BUFFERS, FRAMES AND FILES

Ctrl-x Ctrl-f is "find file," which allows one to find files quickly using command completion in the mini-buffer. Command-O opens a file, but does so using a pattern-matching "find in project" function, similar to Vim's ctrl-p.

These commands both work with tramp, which is a great, great feature. One can open a file on a remote host via sftp by specifying its name like this:

hostname:/path/to/file

Ctrl-x Ctrl-b is the command to switch the current frame (like a pane in tmux, basically a subwindow) to a buffer by name with command completion. It remembers recently open files, so it makes an easy way to open anything one has been working on without hunting around in the file system.

Split the current frame in two vertically by hitting Ctrl-x 2, horizontally by Ctrl-x 3. Close the current frame (but not the underlying buffer/file) with Ctrl-x 0. Close all but the current frame with Ctrl-x 1.

Switching between multiple visible buffers is done using the arrow case modified by M-s. I've set up my browsers and iTerm2 to accept this same shortcut to move between tabs and shells.

NAVIGATION

The emacs-native navigation keys (C-b, C-f, C-p, C-n for backward character, forward character, previous line, next line) are easy and efficient once internalized, but they predate and differ from every other system one is likely to use. This configuration prefers the arrow keys, but maintains the (IMO) most important aspect of the emacs philosophy of movement: the base movement keys can be amplified with modifier keys. M-left will move one word to the left, M-up arrow will move up one paragraph, and so on. Of particular interest for programming modes, C-M-left arrow will navigate left by one sexp (S-expression in lisp terms, but some other "unit of code" in other languages).

The usual OS X bindings for begin/end of line (s-left arrow,s-right arrow) and top/bottom of document (s-up arrow, s-down arrow), page up and page down, and so forth, are also supported.

SEARCHING

Although the above key combinations provide for rapid navigation, one should generally use them only for short movements, preferring to jump around inside a file using search forward (both of C-s and s-f) or search reverse (C-r). Also, if the target is visible on screen, ace-jump-mode is a lovely. It is bound to C-space.

The marvelous visual-regexp is bound to s-r (and visual-query-regexp to s-R). These functions provide regular expression query/replace with a live preview of matches and replacements. The latter 'query' version iterates over the matches, replacing ones where the user presses space and skipping the ones where the user presses delete.

For searching across multiple files, ag provides a simple interface that can be invoked with M-x ag.

DELETING ("KILLING")

Like the arrow keys, deletion (called "killing" in emacs) is amplified with modifier keys. delete does what one would expect, M-delete deletes a word at a time, C-M-delete deletes a paragraph at a time. These deletions go into the kill-ring for future yanking (pasting).

fn-delete deletes to the right (as in other OS X inputs), fn-M-delete deletes to the right one word at a time, and fn-C-M-delete deletes the paragraph to the right.

UNDO/REDO

Command-z is undo, Shift-Command-Z is redo. This functionality is provided by a package called undo-tree, which is similar to the vi package of the same name. It allows one to see recent changes as a decision tree and partially back out changes by choosing branches (like a mini RCS in the editor). The undo visualizer is bound to Control-Command-z.

EXPLORING EMACS

Getting used to the idea that emacs isn't a text editor in the usual sense, but a Lisp environment where a given series of keystrokes are assigned to invoke a particular function is important in learning how to use and customize it.

The collection of functions available in emacs can be explored and invoked by typing M-x and then starting to type a known or probable function name. This will bring up the completion interface in the mini-bar, starting with the most recently executed function. One often does things like:

M-x re to complete and invoke "replace-string"

Consider using the apropos function when you roughly know what you want to do, but aren't sure of the exact function that will do it. M-x apropos prompts you to enter a word (or words) related to what you'd like to do, and creates a buffer for you to browse various functions related to your search term.

Emacs has a ubiquitous help system that allows one to find out the binding of any key, purpose of any function, and so on. Help commands start with ctrl-h (for help!), then a series of letters to indicate what kind of help is being requested. Two of the most useful forms of help for new users are variations on "describe": ctrl-h k (help -> describe keybinding) brings up a prompt that will listen for a series of keystrokes, then report what function is called by that sequence; ctrl-h f (help -> describe function) will provide a similar service for functions using a completion interface. Function descriptions will also list the shortcuts keys that are bound to that function.

If you have trouble remembering a particular key combination, the which-key package tries to help. If it detects a moment of hesitation after entering an incomplete key combination, it will show you a list of possible completions. For instance, in the previous paragraph we discussed two possible completions for C-h: C-h k to describe a keybinding, and C-h f to describe a function. You can discover other help functions by keying just C-h and reviewing the many possible completions.

SOURCE CONTROL

Magit is a nice integrated git for emacs. There are others like it, but this one is my favorite.

DYNAMIC LANGUAGES

SLIME, nREPL, run-ruby, run-python, and so on. There's a great deal of power when interacting with external interpretors in emacs, but it's more than I have time to write about just now. TK.

In emacs lisp, scheme and clojure modes, eval-defun (which evaluates the top level of the current lisp form) and eval-last-sexp are bound to s-enter and s-shift-enter respectively. In most cases the evaluated code will flash momentarily to indicate the scope in which the evaluation occurred. Also, short documentation for the current function should be visible in the mini-buffer and C-c d should pop up further docs on the symbol at point.

RESOURCES

Watch this video on Expand region. This is a feature every code editor should have. In this configuration, it's bound to s-1 and "contract-region" is bound to s-2.

If one intends to hack clojure, Common Lisp, scheme or elisp, it would be wise to get to know SmartParens, which has been added as a replacement for paredit.

Those who build the web should look into skewer-mode for live browser mind control.