A fennel REPL for Hammerspoon

Tue, 29 Mar 2022 19:47:00 +0200

The Fennel programming language is one of my favorite programming languages. It gets a lot of things done right:

Modern syntax (Clojure-like, but better)
Immutable by default
Excellent pattern matching

If I ever find myself working with a Lua interpreter (Hammerspoon, Neovim, TIC-80, etc.), Fennel is often my go-to for concise and efficient code.

The question is, can I have a REPL for Hammerspoon? There are multiple options available, like nREPL via jeejah, but I find it limited compared to the REPL that comes with fennel-mode. Hammerspoon does come with an interactive shell, and I would like to adapt it to work with fennel-mode. In fact, it’s very possible. Hammerspoon comes with a hook, _consoleInputPreparser, that can be hacked to evaluate an expression. Essentially, we can run a REPL in a coroutine and resume it whenever the user inputs something.

(require :hs.ipc)

(local fennel (require :fennel))

(let [coro (coroutine.create fennel.repl)]
  (coroutine.resume coro {:readChunk (fn []
                                       (let [input (coroutine.yield)]
                                         (.. input "\n")))
                          :onValues (fn [xs]
                                      (print (table.concat xs "\t")))
                          :onError (fn [_ msg]
                                     (print msg))})
  (set hs._consoleInputPreparser (fn [s]
                                   (coroutine.resume coro s)
                                   "")))

Here is the result:

And of course, you can evaluate code and get completion with fennel-mode, too.

One-liner to enable Touch ID for sudo

Sat, 01 May 2021 20:23:00 +0200

You may already know how to enable Touch ID for sudo already, but it’s constantly getting disabled after each update of macOS. This one-liner is a no-brainer to enable it again. Basically, type it once in your terminal, and type ‘^R pam.d ENTER’ to enable it again once needed and it will be enabled again.

sudo sed -i '' '2i\
auth       sufficient     pam_tid.so
' /etc/pam.d/sudo

ATTACH on QL's blog

A fennel REPL for Hammerspoon

One-liner to enable Touch ID for sudo