Hammerspoon directional focus

init.lua

function directionalFocus(selector)
  local current = hs.window.focusedWindow()
  local currentFrame = current:frame()
  local others = hs.window.orderedWindows()
  for i, win in pairs(others) do
    local otherFrame = win:frame()
    local intersect = otherFrame:intersect(currentFrame)
    if intersect.area == 0 and selector(currentFrame, otherFrame, intersect) then
      win:focus()
      break
    end
  end
end

hs.hotkey.bind({"cmd", "alt", "ctrl"}, "left", function()
  directionalFocus(function(current, other, intersect)
    return other.x2 <= current.x and intersect.h ~= 0
  end)
end)

hs.hotkey.bind({"cmd", "alt", "ctrl"}, "right", function()
  directionalFocus(function(current, other, intersect)
    return other.x >= current.x2 and intersect.h ~= 0
  end)
end)

hs.hotkey.bind({"cmd", "alt", "ctrl"}, "up", function()
  directionalFocus(function(current, other, intersect)
    return other.y2 <= current.y and intersect.w ~= 0
  end)
end)

hs.hotkey.bind({"cmd", "alt", "ctrl"}, "down", function()
  directionalFocus(function(current, other, intersect)
    return other.y >= current.y2 and intersect.w ~= 0
  end)
end)