In the last 6 month I have started to wonder.
First of all … I am convinced that using the concepts of functional programming will give you better results (more maintainable/changeable/extendable code). Not embracing functional programming will (sooner or later) put you (and the organisation you are leading) at a competitive disadvantage (compared to those who do).
I like Haskell. A lot. I like it even more now after I discovered eta (Haskell on the JVM).