Thanks for the feedback, @notriddle!
You’re definitely right about the string inside string interpolation case. I’ll try and fix it soon.
I was in two minds whether to make %{"THIS": :foo} highlight as an atom or not. I decided to go with the string highlighting because it made the string detection much faster, using some short circuiting logic in the code. But in the end I think you’re right on that one as well, and I should make it display as atom as well.
Allow me to bump the topic, since I run into ugly, non-highligthed code on SO once more and it boiled my blood a bit again.
To summarise the situation, the feature has been requested four and a half years ago and about a year ago I wrote the highlighter necessary for the SO people to integrate Elixir highlighting with their site without breaking much of a sweat. Still, there hasn’t been any progress on the issue since, and it looks like SO has a policy on not improving syntax highlighting on the site ever again.
While I have no reason to be optimistic about the whole situation, it feels like it would be good to raise the profile of the feature request, or otherwise nothing is going to change. From what I’m reading the best bet is to upvote the request and add/or add a bounty for it. I’d happily do it myself, but I don’t have enough karma on Meta Stack Exchange…
Soo I guess what I’m saying is: Does anyone have some Meta Stack Exchange karma to use for a good cause? :]
Edit: I’m curious, which of the other Most Loved Languages according to SO Developer Survey 2017 don’t have the syntax highlighting support 
We’re half way through 2018 and there’s still no Elixir syntax highlighting on Stackoverflow – That’s disappointing. I just opened a support thread on Meta, asking for help on the topic:
If anyone still cares about this, a quick upvote here could help: https://meta.stackexchange.com/questions/360682/syntax-highlight-request-elixir