> If people who only know JS and won't learn anything new can't contribute then that's a cost worth bearing.

I think this is an unfair and unnecessarily-snarky take.

My list of languages is fairly long these days. I’ve written php, ruby, and go in reasonable volume for mostly personal projects. I used to teach embedded C at uni. I write python professionally every day. Recently I’ve even started playing with rust (and had some success thanks to the awesome book). The list is far longer, these are just the ones used the most. I’ve been writing code in some capacity for the last 20 or so years (first self-taught, then at university, and more recently professionally full-time).

Despite all that, and not for lack of trying, for whatever reason purely functional languages are the only ones that elude me. Every couple of years I try Haskell or erlang again and I just get nowhere fast.

Maybe it’s because I was never very good at maths, maybe it’s because I haven’t had sufficient motivation, or maybe I just haven’t found the right monad blog post to convert me. All I know is Haskell remains chronically out of reach to many experienced and inexperienced devs alike.