Karabiner (via Goku)

Configure macOS keyboard remapping with GokuRakuJoudo - an EDN-based DSL that compiles to Karabiner-Elements JSON.

Why Goku?

Karabiner's native JSON is verbose (20,000+ lines). Goku's EDN format is 10-50x more concise:

;; Goku: 1 line
[:caps_lock :escape]

;; Karabiner JSON: ~30 lines

Prerequisites

# Install Goku
brew install yqrashawn/goku/goku

# Start as service (watches ~/.config/karabiner.edn)
brew services start goku

# Or run once manually
goku

Config location: ~/.config/karabiner.edn

Logs: ~/Library/Logs/goku.log

EDN Syntax Quick Reference

Basic Structure

{:main [{:des "Rule description"
         :rules [[:from :to]
                 [:from2 :to2]]}]}

Keycodes

All keys use keyword syntax: :a, :1, :f19, :spacebar, :return_or_enter

Find keycodes:

• Run Karabiner-EventViewer.app
• See keys_info.clj

Modifier Syntax

Combine modifiers: :!CTSa = Cmd+Ctrl+Shift+A

Rule Format

[:from :to]                           ;; Basic
[:from :to :condition]                ;; With condition
[:from :to :condition {:alone :x}]    ;; With options

Multiple Keys

;; Press sequence
[:a [:1 :2 :3]]           ;; a -> types 1, 2, 3

;; Simultaneous press (from)
[[:j :k] :escape]         ;; j+k together -> escape

Shell Commands

[:!!1 "open -a Safari"]   ;; Hyper+1 runs shell command

Conditions

Application Conditions

{:applications {:chrome ["^com\\.google\\.Chrome$"]
                :code   ["com.microsoft.VSCode"]}
 :main [{:des "Chrome only"
         :rules [[:a :b :chrome]]}]}

Device Conditions

{:devices {:hhkb [{:vendor_id 1278 :product_id 51966}]}
 :main [{:rules [[:a :b :hhkb]]}]}

Input Source Conditions

{:input-sources {:us {:input_source_id "com.apple.keylayout.US"}}
 :main [{:rules [[:a :b :us]]}]}

Combining & Negating Conditions

[:a :b [:chrome :hhkb]]    ;; Both conditions
[:a :b [:!chrome]]         ;; NOT in Chrome

Layers

Simlayers (Recommended)

Fast, simultaneous-key based layers - best for typing speed:

{:simlayers {:w-mode {:key :w}}        ;; Hold W activates layer
 :main [{:des "w-mode shortcuts"
         :rules [:w-mode                ;; Apply to this layer
                 [:e "open -a Finder"]  ;; W+E opens Finder
                 [:r "open -a Safari"]  ;; W+R opens Safari
                 ]}]}

Simlayer options:

{:simlayers {:w-mode {:key :w
                      :modi {:mandatory [:left_control]}}}}  ;; Ctrl+W activates

Standard Layers (Tap/Hold)

Different behavior on tap vs hold:

{:layers {:caps-mode {:key :caps_lock
                      :alone {:key :escape}}}}  ;; Tap=Esc, Hold=layer

Manual Layer Variables

;; Set variable on keydown, clear on keyup
[:w ["w-mode" 1] nil {:afterup ["w-mode" 0] :alone :w}]

;; Use the variable as condition
[:e :!Ce ["w-mode" 1]]  ;; W+E -> Cmd+E (only when w-mode=1)

Templates

Reusable shell command patterns:

{:templates {:open "open -a '%s'"
             :launch "/path/to/script.sh %s"
             :alfred "osascript -e 'tell application \"Alfred\" to run trigger \"%s\"'"}
 :main [{:rules [[:!!1 [:open "Safari"]]      ;; %s replaced with Safari
                 [:!!2 [:launch "arg1"]]]}]}

Predefined Aliases

:froms (Input Keys)

{:froms {:delete {:key :delete_or_backspace}
         :return {:key :return_or_enter}
         :mouse1 {:pkey :button1}}}

:tos (Output Actions)

{:tos {:spotlight {:key :spacebar :modi :command}
       :paste {:key :v :modi :command}
       :shift-click {:pkey :button1 :modi :left_shift}}}

Custom Modifier Sets

{:modifiers {:hyper [:command :shift :control :option]
             :meh   [:shift :control :option]}}

Advanced Options

Fourth position in rules:

[:from :to :condition {
  :alone :key              ;; to_if_alone
  :held :key               ;; to_if_held_down
  :afterup :key            ;; to_after_key_up
  :delayed {:invoked :x :canceled :y}
  :params {:alone_timeout 200}
}]

Profile Settings

{:profiles {:Default {:default true
                      :sim 250        ;; Simultaneous threshold (ms)
                      :delay 500      ;; Delayed action time (ms)
                      :alone 1000     ;; to_if_alone timeout (ms)
                      :held 500}}}    ;; Held threshold (ms)

Common Workflows

Add a Simple Remap

{:main [{:des "Caps to Escape"
         :rules [[:caps_lock :escape]]}]}

Add App-Specific Shortcut

{:applications {:chrome ["com.google.Chrome"]}
 :main [{:des "Chrome shortcuts"
         :rules [[:!Cl :!Ct :chrome]]}]}  ;; Cmd+L -> Cmd+T in Chrome

Create a Layer

{:simlayers {:nav {:key :spacebar}}
 :main [{:des "Navigation layer"
         :rules [:nav
                 [:h :left_arrow]
                 [:j :down_arrow]
                 [:k :up_arrow]
                 [:l :right_arrow]]}]}

Hyper Key Setup

{:main [{:des "Caps Lock to Hyper"
         :rules [[:caps_lock :!CTOSleft_shift nil {:alone :escape}]]}]}

CLI Commands

goku           # Compile karabiner.edn once
gokuw          # Watch mode (compile on change)
goku -h        # Help

# Service management
brew services start goku    # Start watch service
brew services stop goku     # Stop service
brew services restart goku  # Restart after changes

# Check logs
tail -f ~/Library/Logs/goku.log

Validation & Debugging

1. Check syntax: Goku reports EDN parse errors
2. View output: ~/.config/karabiner/karabiner.json
3. Use EventViewer: Karabiner-EventViewer.app shows key events
4. Check logs: tail ~/Library/Logs/goku.log

Best Practices

1. Use simlayers for frequently-accessed shortcuts (faster than hold-layers)
2. Group rules by purpose with descriptive :des tags
3. Use templates for repeated shell command patterns
4. Define aliases in :froms/:tos for complex key definitions
5. Test incrementally - add one rule, verify, repeat
6. Back up your config before major changes

Resources

• Tutorial
• Examples
• Configs in the wild
• Keycodes reference