Yes, there's a need for it, and Bluefin provides Modify which allows you to modify a reference to a value in a way that is not observable outside the scope of t

Yes, there's a need for it, and Bluefin provides Modify which allows you to modify a reference to a value in a way that is not observable outside the scope of the capability. https://hackage-content.haskell.org/package/bluefin-0.6.0.0/docs/Bluefin-Capability-Modify.html https://hackage-content.haskell.org/package/bluefin-0.6.0.0/...