Favorite Apps & Tools #5 - Hammerspoon


Hammerspoon about Hammerspoon:

This is a tool for powerful automation of OS X. At its core, Hammerspoon is just a bridge between the operating system and a Lua scripting engine. What gives Hammerspoon its power is a set of extensions that expose specific pieces of system functionality, to the user.


Well that part was easy, but why do I need Hammerspoon? There is Applescript, Automator and even the whole power of a proper shell, the BSD General Commands and the sort built-in, right.

Pretty simple really: With Hammerspoon, I can combine all of the above and more within just the one tool. Plus if all fails, I can run arbitrary external scripts, as mention in my Favorite Apps & Tools introduction post.

There is an added benefit of a reasonable – much more reasonable, than the built-in System Preferences – system for binding keyboard shortcuts for your automation.

Another Bonus is that you can have all, all of you automation in one plain text file. Now that is what I call portable.


Following are some examples, that I am implementing on my Mac.

Launch Application

Of course I have an Application launcher, Alfred – a separate post to follow. However some applications have a VIP status and need an exclusive manner to get started.

function launch_emacs ()
hs.hotkey.bind({"cmd", "alt", "ctrl"}, 'e', launch_emacs)

Windows management

There are some dedicated applications/tools to bring tilling to macOS, but I deem them superfluous. I can implement almost all the functions within Hammerspoon.

For the sake of keeping this reasonably short, I will not list all of them here. If you are curious go find the entire setup on my Gitlab.

ctalcm = {"cmd", "alt", "ctrl"}
-- possible ass well: ctalcm = {"⌃", "⌥", "⌘"}

-- send window to screen by number
function moveWindowToDisplay(d)
   return function()
      local displays = hs.screen.allScreens()
      local win = hs.window.focusedWindow()
      win:moveToScreen(displays[d], false, true)

hs.hotkey.bind(ctalcm, "1", moveWindowToDisplay(1))
hs.hotkey.bind(ctalcm, "2", moveWindowToDisplay(2))
hs.hotkey.bind(ctalcm, "3", moveWindowToDisplay(3))

Emacs capture window from everywhere

With the following hotkey I can pull up an Emacs capture window from everywhere in macOS. Don’t know Emacs? Check out my post about it.

ctalcm = {"cmd", "alt", "ctrl"}

-- capture window from everywhere
hs.hotkey.bindSpec({ctalcm , "c"},
      hs.execute("/usr/local/bin/emacsclient -ne '(make-capture-frame)'")


Despite the name, Hammerspoon is not the proverbial hammer. It is flexible enough to handle almost all the automation needs on my Mac.

Because of that I am in the process of moving all “legacy” configurations for automation into Hammerspoon.

Not convinced yet. Head over to the Getting started page and see some great examples.