IHP is a nice product and works really well for my side project; hopefully I can convince my colleagues to use it for our main project too.
I'm pretty fluent in Haskell, but finding Haskell jobs is hard compared to OCaml or F#, which are a bit of a niche of their own. Actually, I routinely get OCaml offers when advertising Haskell on my CV. I find this interesting and exciting as OCaml was not very frequent outside academia a few years back.
Long statements, but I really do think employee retention and personal fulfillment would lead to a better working environment. So that is the way I’d argue it. Obviously a comprehensive sampling of performance metrics would be needed along with the more HR reasonings, but I think there are plenty of examples where Haskell is performing acceptably.