Monadic Library for Eio Capabilities?

Learning
64

I respond to myself. After some reflexion, I fear that the security model of Eio is broken by the dynamic dispatch as exposed by the Resource module.

let foo (src : _ Flow.source) =
  let (Resource.T (t, ops)) = src in
  match Resource.get_opt ops Sink with
  | Some (module M) -> (* I gain write access to my source *)
  | None -> (* everything is fine)

Normally, if I pass a _ Flow.two_way to fooit should not be allowed to write to it, but I will fall in the Some branch and foo has gained privilege it should not have.

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