Boon: An Ergonomic Command Mode for Emacs

Boon is a complete package for modal editing, which is not Evil.

Selling points:

• Ergonomic: common commands are easy to type. (See below)
• Lightweight: ~300 loc for its core.
• Good Emacs integration: integrates with existing Emacs infrastructure and takes advantage of it.

Ergonomic Design

It is largely accepted that modal edition is more ergonomic than using key-chords. Boon attempts to make modal editing as comfortable as possible, by adhering to the following design principles:

• Spacial allocation first, mnemonics second: the allocation of keys to commands is based in priority on the locations of keys on the keyboard. Whatever is printed on the key cap is a secondary concern.

• Easy finger rolls: common combination should either be left/right hand alternation or easy one-hand rolls.

• Use of home row and strong fingers for the most used commands

• Easy navigation: many commands are bound to navigation. This facilitates moving around. Because movements double up as region-definitions, it makes manipulation commands (operators) more powerful.

In command mode, movement keys are bound to the right hand, while text manipulation is bound to the left hand.

Right-hand.

The leftwards (and upwards) movements are bound to the leftmost fingers (index and middle finger), while rightwards (and downwards) movements are bound to the rightmost fingers (ring finger and pinky.) Additional movements are bound to the middle column.

Left-hand.

The most common edition commands (cut, paste, parenthesis manipulation) are bound to the home row. The top row is (mainly) for searching. The bottom row gives access to regular Emacs stuff (C-x ...) (C-c ...) and registers.

Emacs Integration: Reusable Modules

Boon is designed as a series of layer, which are customizable and provide reusable components, in full agreement with the Emacs spirit. This means that even if you disagree with the frontend choices made above, you may still want to use some parts of Boon. The structure of Boon is as follows:

1. boon-moves, boon-search: a set of move and search commands. These work the same way as standard Emacs commands; they are merely (maybe) more powerful. Frontends typically bind these commands (and more) in boon-moves-map, which is active in 'command mode'.
2. boon-arguments: a set of selectors to define regions. (Equivalent of vim 'text objects'.) Selectors include plain regions (words, lines, paragraphs, ...), but also region transformers (think: exclude borders, just borders, including spaces, foreach, etc.). Additionally every move command in boon-moves-map can be used as a selector. The system supports multiple cursors. These selectors are regular interactive functions.
3. boon-core: An infrastructure for modal editing, inspired from evil-core.
4. boon-main: A set of commands similar to standard Emacs commands, but which uses the system of selectors. (Additionally some random extra commands are thrown in for good measure.) These commands may be used in combination with a modal system, or not. A few commands also switch to insert mode.
5. boon-keys, boon-extras, boon-colemak, boon-qwerty, ...: frontends. Those 'require all the above and provide a mapping of moves, selectors and commands onto keys. They may also bind keys for other 'modes', such as helm.

Installation/Configuration

REQUIREMENTS

• Emacs version >= 24.5
• Colemak layout (qwerty version exists but tutorial assumes colemak layout)

Install Boon (perhaps using ), and add the following to your configuration:

(require 'boon-colemak)
;; (require 'boon-qwerty) ;; for qwerty port (alpha quality)
(boon-powerline-theme) ;; if you want use powerline with Boon
(boon-mode) ;; to enable boon everywhere (use M-x turn-on-boon-mode) to try locally

You can jump-start by reading the cheat sheet directly, but reading through this modified (and shortened) version of the Emacs tutorial is recommended:

TUTORIAL.txt

Comparison with other modal layers for Emacs

As far as I know, none of the other modal mode care about ergonomics (beside being modal).

• Evil

  Evil is a (quite) complete vi emulation layer for Emacs.

  In Boon, quite a bit of Emacs structure and user experience is retained. Examples: the x key gives the C-x prefix map. The usual Emacs (interactive) arguments are used for text objects. Thus most of Boon remains usable even if one does not wish to use modal editing.

  Besides, Emacs is already customizable enough as it is: the core of Boon is just 300 lines or so. Figuring out all the ins and outs of Evil to do what I want would probably have required more effort than implementing Boon.

  Finally, evil use vi bindings (by default at least), which do not feature the best ergonomics.

• Fingers https://github.com/fgeller/fingers.el

  Fingers borrows a few ideas from Boon, including the division of work between left and right hand. fgeller gives a detailed account of the particular differences with Boon. My opinion is that fingers is compatible with Boon concepts and could be implemented as a Boon 'frontend'.

• God-mode https://github.com/chrisdone/god-mode

  God-mode is similar to "sticky modifier keys" in principle. Its simplicity allows to quickly get up to speed with it. However, it lacks the main benefit of a true modal layer: text operators. (what vi fans call a "language for text edition").

• Modal Mode http://retroj.net/modal-mode

  Another modal layer for Emacs, which is also lightweight and aims to integrate with Emacs. However, as far as I can see, there is no special attention to ergonomics.

• Modal Emacs https://github.com/joelmccracken/modal-emacs

  Modal Emacs does not appear to be complete.