I've been doing professional FP work for 20+ years at this point. Haskell has community was the biggest killer for me. It was great when I made the jump from Standard ML to Haskell about 15 years ago. About 5 years ago I just couldn't stand what it had morphed into any longer - from the tension created by certain companies to well known community members who were just trouble for one reason or another. Instead of returning to Standard ML, I've been doing Ocaml for the last 5 years or so and couldn't be happier.