Hammerspoon capslock remapping: tap to Escape, hold in chord for Control

remap_capslock.lua

-- Inspired by https://github.com/jasoncodes/dotfiles/blob/master/hammerspoon/control_escape.lua
-- You'll also have to install Karabiner Elements and map caps_lock to left_control there
len = function(t)
    local length = 0
    for k, v in pairs(t) do
    	length = length + 1
    end
    return length
end


send_escape = false
prev_modifiers = {}

modifier_handler = function(evt)
    -- evt:getFlags() holds the modifiers that are currently held down
    local curr_modifiers = evt:getFlags()

    if curr_modifiers["ctrl"] and len(curr_modifiers) == 1 and len(prev_modifiers) == 0 then
        -- We need this here because we might have had additional modifiers, which
        -- we don't want to lead to an escape, e.g. [Ctrl + Cmd] —> [Ctrl] —> [ ]
        send_escape = true
    elseif prev_modifiers["ctrl"]  and len(curr_modifiers) == 0 and send_escape then
		send_escape = false
        hs.eventtap.keyStroke({}, "ESCAPE")
    else
        send_escape = false
	end
    prev_modifiers = curr_modifiers
	return false
end


-- Call the modifier_handler function anytime a modifier key is pressed or released
modifier_tap = hs.eventtap.new({hs.eventtap.event.types.flagsChanged}, modifier_handler)
modifier_tap:start()


-- If any non-modifier key is pressed, we know we won't be sending an escape
non_modifier_tap = hs.eventtap.new({hs.eventtap.event.types.keyDown}, function(evt)
    send_escape = false
	return false
end)
non_modifier_tap:start()