Yeah, I'm never sure about language extensions. I've been trying really hard to avoid just adding them willy-nilly to solve various problems, but I've found there are at least 4ish that I include by default on every new Haskell project I write (and I'm up to 9 on my current project!). Sometimes it feels like their existence is a hindrance to fixing some flaws in the base language (Haskell without OverloadedStrings makes me sad)