The Flix programming language might include Ocaps in the future

[Pierre Thierry]

Flix is an interesting functional programming language that includes polymorphic side effects, meaning a function like map() can say it will be pure when applying a pure function to a list but impure when applying an impure function to a list…

https://flix.dev/

I asked if capability-safety might get added there and the designers seem to be already interested:

https://github.com/flix/flix/issues/2837