Haskell is being used for their spam filtering system, Sigma: https://code.fb.com/security/fighting-spam-with-haskell/ https://code.fb.com/security/fighting-spa

Haskell is being used for their spam filtering system, Sigma: https://code.fb.com/security/fighting-spam-with-haskell/ https://code.fb.com/security/fighting-spam-with-haskell/ I'm not sure what else they use it for, but they hired Simon Marlow, one of the main guys behind GHC a years ago. It's still not their primary language, but restricting the interpretation of "professional" and "uses" to what you had in mind is not the most interpretation of your comment to me.