System Crafters Live! - July 16, 2021

¶Do we really need use-package?

use-package is a (very?) commonly used package for writing one's Emacs configuration in a more "concise" way. It provides a macro called use-package which removes some boilerplate needed in Emacs configs.

If you followed my Emacs From Scratch series, you're probably using it!

I've been experimenting with a new configuration lately which doesn't use use-package. Why?

¶The value of use-package

use-package certainly provides some useful features:

• It can make your configuration appear more concise and well-organized
• Installs external packages when necessary
• Streamlined configuration of key bindings, hooks, faces, and custom variables
• Can set up "autoloads" for commands that don't already have them
• Makes init.el look more like a configuration file syntax instead of code, more beginner friendly?

What else?

¶The downsides of use-package

In my opinion, there are a few downsides to using use-package, especially for new Emacs users:

• Obscures the underlying Emacs Lisp code for configuration by providing a different syntax that must be learned
• Encourages you to cram all the config for a package inside of one expression
• :init vs :config is confusing to new users
• Harder to really understand when packages will be loaded

With all that said, I'm not recommending that people get rid of use-package!

This conversation is mainly an exercise to make us think critically about what it provides and look at that the equivalent Emacs Lisp would be.

¶What does use-package really do?

I mentioned before that use-package is a macro, but what does that mean?

In Lisp languages, a macro can be thought of like a "code template" which is defined like a function but operates slightly differently.

Instead of the arguments to the macro "function" being evaluated and then passed in, the arguments are not evaluated. The body of the macro "function" returns the real code that should be executed instead!

We can use M-x emacs-lisp-macroexpand with the cursor before a macro call to expand it into the resulting forms. We'll use this in the Emacs From Scratch configuration to understand what use-package does and then convert it to plain Emacs Lisp!

¶Features to investigate

• :ensure t
• :after
• :config and :init
• :custom (use custom-set-variables?)
• :defer
• :bind
• :hook
• :commands
• :mode

¶What would we need in Emacs?

I think that with some additional built-in helpers in Emacs, packages like use-package would be less necessary:

• A macro for defining multiple keys more easily
• A macro (or optional args to add-hook) for adding multiple hooks more easily
• A macro for setting custom variables

Take a look at leaf: https://github.com/conao3/leaf.el