[muglug]

> With Hack's extensive static type checking and even contexts / coeffects

Have you used contexts/coeffects?

My understanding is that it's still yet to be fully rolled out to WWW, and nobody outside FB has yet played around with it. IMO it still has some DX issues (https://github.com/facebook/hhvm/issues/8828) and the examples given in documentation don't actually work in real life (https://github.com/hhvm/user-documentation/issues/1016).

[nine_k]

Not extensively; rather, I had to pay attention to the limitations that a particular context enforces.

It's definitely a fresh feature, iirc rolled out last winter.