I struggled with The Little Lisper (as it was called at the time) in school but as I approach the other end of my career I've given some thought to working through it again. I think it would come a lot more easily now. Though I looked at Haskell maybe 10 years ago and never got traction with it.

Functional or declarative programming styles appeal to me, and I love what I've learned of Erlang but never really had a job where I could use it. Used SQL a lot and quite like it as well.