Haskell is too special, to be used in typical large project.

But in real projects, are in wide use other pure functional langs (trying to write most popular first): - Erlang (telco, finance) - Lisp (finance, CAD) - Scala (basically universal) - Scheme (basically universal) - Elixir (frontend) - Clojure (don't know much, looks like also frontend).

But in most cases, they are sort of DSL, because functional paradigm is much better in some niches, but not so good in others.