parinfer.js

I develop Cursive, an IDE for Clojure code, and I spent a long time integrating parinfer smart mode. It was actually really difficult to do well, I wrote a document with feedback about what (among other things I discovered later) that made it hard: https://github.com/parinfer/parinfer.js/wiki/Problems-integr.... I subsequently fixed many of those issues, but it was probably the second hardest thing I've integrated into Cursive, after Leiningen. It's still a bit quirky, but I use it every day and I love it. Even though I'm proficient enough with paredit, parinfer is just so much easier to use. Several users have commented to me that the parinfer integration is the main thing stopping them switching away to a different editor - it really makes that much difference.