Nested leader key

[saml-dev]

Is it possible? For example, a regular leader key layer is easy to set up. leader t for terminal, leader m for messages, etc. But what if I wanted to set up a Raycast layer, where leader r c opens the camera, leader r a toggles system appearance (dark mode), leader r e opens the emoji picker, etc. Is that possible with Karabiner / karabiner.ts?

[evan-liu]

Hi @saml-dev. There is no abstraction over it with karabiner.ts right now. I thought about this feature but couldn't find a good API.

However, I think it is definitively possible. Can you try if you can make it work yourself:

• On the layer,

.leaderMode({ sticky: true })

• Inside the layer, map the "sub-layer" trigger to set a variable, e.g.

map('r').toVar('sublayer-raycast')

• For each key on the "sub-layer", unset both the layer and the sub-layer key, e.g.

 withCondition(ifVar('sublayer-raycast'))([
   map('c')
     .toApp('someApp')
     .toUnsetVar('sublayer-raycast')
     .toUnsetVar('layerVar'),
 ]),

If it works, the unset var part can then be abstracted into a mapper or function.

[evan-liu]

Hi @saml-dev, I've put together an working example (open in online editor), please let me know if it helps:

let raycastEmoji = 'raycast/emoji-symbols/search-emoji-symbols'
let escape = [toUnsetVar('leader'), toRemoveNotificationMessage('leader')]

let rules = [
  rule('Leader Key').manipulators([
    // When no leader key or nested leader key is on
    withCondition(ifVar('leader', 0))([
      // Leader key
      map('l', 'Hyper') // Or mapSimultaneous(['l', ';']) ...
        .toVar('leader', 1)
        .toNotificationMessage('leader', 'Leader Key: Open, Raycast, ...'),
    ]),

    // When leader key or nested leader key is on
    withCondition(ifVar('leader', 0).unless())([
      // Escape key(s)
      map('escape').to(escape),
    ]),

    // When leader key but no nested leader key is on
    withCondition(ifVar('leader', 1))([
      // Nested leader keys
      withMapper(['o', 'r'])((x) =>
        map(x)
          .toVar('leader', x)
          .toNotificationMessage('leader', `leader ${x}`),
      ),
    ]),

    // leader o - Open
    withCondition(ifVar('leader', 'o'))(
      [
        map('f').toApp('Finder'),
        // f - Finder, ...
      ].map((x) => x.to(escape)),
    ),

    // leader r - Raycast
    withCondition(ifVar('leader', 'r'))(
      [
        map('e').to$(`open raycast://extensions/${raycastEmoji}`),
        // e - Emoji, ...
      ].map((x) => x.to(escape)),
    ),
  ]),
]

[saml-dev]

Wow nice, good work! It's complex but cool that it works. I ended up trying out Hammerspoon's RecursiveBinder which also gives leader key functionality, and I'm going to stick with that. I wrote some Lua on top of it so that I can write a toml config like this to configure nested keymaps:

leader_key = "f18"


b = "Zen Browser"
v = ["Visual Studio Code", "VS Code"]
t = ["Ghostty", "Terminal"]
c = [
    "raycast://extensions/raycast/window-management/center-half",
    "window:center",
]


[a]
label = "[apps]"
t = "Todoist"
e = "https://gmail.com"
m = "Messages"
r = "Raindrop"
c = ["https://calendar.google.com", "Calendar"]

I found this to be low friction and it also has live reloading so fun to play with.

thanks for looking into it, and I'm glad you ended up using it in your config too!

[evan-liu]

By the way, I've also changed some of my layers to nested leader keys.