That looks really cool. Can you narrow Bluefin.IO to reads/writes separately? One of the things I've worked on is the ability to allow code to read files, even specific files, but deny writes.
Yes! It started as an implementation of the effect system I always wanted: effects passed on the value level, rather than implicitly on the type level. Once I'd done that I realise that it was actually a capability system (and that was the better way of describing it, because more people already know what a "capability system" is).
Here you go! It's a complete document, but I'll continue to edit it over the next few days before I announce it. I'd love to hear any thoughts you have.
