0fcb6a4 Jan 12, 2016
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This document assumes the user.keymap introduction and the user.behaviors introduction have been read.


Keymap and behaviors files are ClojureScript data that when merged together create LightTable's final keys and functionality. A user can add or remove any keybinding/behavior. This is powerful as any default keybinding/behavior, whether from LightTable or a plugin, can be removed or overridden by a user. Next this document will cover configuring behaviors and keybindings through tags, keys and commands.


Tags allow keybindings/behaviors to apply in different contexts i.e. enter means something different in a url bar vs a popup. Under the hood, objects have tags added and removed which makes a keybinding/behavior apply or not apply to them respectively. Tags can have optional extensions that make them apply in different contexts. For example to have the :editor tag only apply to a file for a given filetype use the format :editor.FILETYPE e.g. :editor.javascript. Note that for the same keybinding/behavior a tag with an extension takes precedence over one without.

There are a number of tags that only apply in a unique UI context or widget e.g. a browser. Here are some common ones:

  • :browser - Applies when inside a browser tab
  • - Applies when hinting/autocomplete is active
  • :filter-list.input - Applies when in a filter-list e.g. Commands pane or Navigator

For more tags see the ones used by default in default.keymap and default.behaviors and search LightTable for when a context tag is added with ctx/in!.



LightTable uses mousetrap for keyboard handling. Mousetrap recognizes the following modifier keys: shift, ctrl, alt/option and command/cmd. LightTable also recognizes pmeta which is command/cmd in OSX and ctrl anywhere else. To specify other special keys like 'enter' see this Mousetrap documentation. LightTable also supports key combinations/sequences when keys are separated by a space. This allows plugins like Emacs to support key chords like 'ctrl-x u'.

Keybindings and tags with multiple extensions

To override a keybinding that has multiple extensions e.g. :editor.keys.normal, you must specify a tag that has the same prefix and than an additional extension e.g. :editor.keys.normal.clojure. As an example, let's override the backspace key which is tagged with :editor.keys.normal but only in a clojure file. In user.behaviors, create a tag when in clojure files which will override editor.keys.normal with [:editor.cljs :lt.object/add-tag :editor.keys.normal.clojure]. Then in user.keymap, use the tag with [:editor.keys.normal.clojure "backspace" :add-browser-tab]. Backspacing in a clojure tab should now add a browser tab - not that most useful thing ;).

Commands In Keybindings

Keybindings can run multiple commands by appending them to the end e.g. [:TAG "KEYS" :COMMAND1 :COMMAND2]. While commands are started serially, there isn't a guarantee that one command is fully finished before the next proceeds. Any commands that have asynchronous functionality e.g. interaction with a network or filesystem cannot guarantee when their functionality is complete. Commands can have arguments passed to them by wrapping them in parenthesis e.g. (:COMMAND ARG1 ARG2). For example [:tabs "pmeta-1" (:tabs.goto 0)] is a default keybinding that passes 0 as an argument to the :tabs.goto command.