Facebook uses Haskell for [Haxl](https://github.com/facebook/Haxl), Standard Chartered has a their own Haskell [compiler](https://www.reddit.com/r/haskell/comments/6im268/standard_ch...) and a massive code base in Haskell. [Agda](https://github.com/agda/agda) and [Idris](https://github.com/idris-lang/Idris-dev) were mostly written in Haskell as well.