I made the switch to FP. I first learnt Basic then Delphi then C then Java then C# then Python then JS and now Scala. Python is my still my favourite and I really like Scala too. Anyway, I could write big stuff in any typed language OO or otherwise. I don't get what the revelation about FP is. If you want bullet proof code, get the model checker out and work in state machines. That is far the biggest revelation I have had in my career. FP doesn't save me much time or much safety . It doesn't solve concurrency. Its usually terser which is nice. That's about it. Python is a massive productivity boost but it doesn't scale. Scala scales but isn't that productive IMHO.