In my old job, I used haskell for everything from satellital image analysis to the web frontend, but I didn't tell anyone. Specially I didn't tell my bosses.
When they discovered my functional tendencies, they were upset and worried. They feel betrayed, but it was too late. The company was an "haskell powered company".
I give them an edge over the other companies in the field, but when I leave, they were orphaned and unable to hire a new Haskell programmer (I live in Chile, a very imperative nation).
Too bad for them, but for me, it was "pure" functional fun.