> You're lucky enough if you can find a developer who knows mutable data structures outside of SF.

That's one of the most arrogant statements I've read on HN in quite a while.

Nearly all developers know mutable data structures, it's bread and butter. Immutable ones aren't some exotic life form, it's just that using them effectively (read: efficiently) as mutable ones can be really tough, and leads to more complex code.

You should maybe get out of SF for a bit.

I am out of SF. The number of times I've seen people start trying to parse XML with regular expression tell me all I need to know about their ability to code.

You probably should take a visit to UK.

Standard Chartered has been a Haskell shop for a long time. There are some others in London I think.

And both England and Scotland have many universities teach Haskell. Let alone GHC and Idris were born in Scotland.

I've had random interns enter a purely functional codebase with 0 FP background. With a normal amount of onboarding, they were using immutable data structures with ease.