Functional programming is rare. It's sort of like the PS3 when it came out. Better specs across the board but harder to use and understand so it's hard for me to point to production level examples. Facebook does have one big project done in haskell you can look into that. Also whatsapp is done entirely in erlang.

Also note that the trend I see in the industry is not exactly movement towards functional programs but more movement towards borrowing features popular in functional programming as well as getting rid of classes.