I watched this presentation last night about introducing Clojure in
the workplace, Bootstrapping Clojure. Most of the video is
Tyler presenting code he wrote, so there’s a lot of Clojure code
displayed in the presentation. The way he presented the code itself
was interesting: indentation was highlighted in alternating shades of
Such emphasis on indentation could be useful specifically for reading
Lisp, because, for humans, what makes s-expressions readable isn’t the
parenthesis but the indentation. That’s why us Lispers shake our heads
when non-Lispers complain that there are too many parenthesis. We
don’t notice them!
He’s a Vim user so I assume this is some Vim extension, but maybe it’s
just the output from a particular pretty printer. I thought it would
be interesting to have this feature in Emacs, so I created a minor
mode for it.
Here’s what it looks like with the default Emacs theme.
And some Java with
visual-indentation-width set to 4,
Dark themes (like the Wombat theme I personally use) will work as
well, with the indentation highlighting appearing darker.
It can be enabled by default in all programming modes easily,
(add-hook 'prog-mode-hook 'visual-indentation-mode)
It completely falls apart when tabs are used for indentation, which
Emacs will use by default. My configuration
forbids tabs (tabs are stupid, people!) but I still need to edit other
people’s code containing tabs. I don’t think there’s a way to apply
highlighting to part of a tab, so I’m not sure if there’s a way to
fix that. Because I don’t intend to actually use the mode regularly,
it’s just a proof of concept, and fixing it would be non-trivial, I
don’t intend to fix it.