I don't understand why this is noteworthy. I think maybe this is when you decide 'maybe our language has failed'. Or at least admit it's a toy language that hasn't been properly engineered to be effectively used commercially. When it's a 'worth mentioning' when a single app has been written in it by some dying company. I mean, imagine if we had a headline on the frontpage of HN for every app written in C or C++ or Ja…
Whatsapp was written in a FP, as is a large segment of Cisco router control plane. React arguably is strongly pushing towards a FP subset of ECMA6.