Re: [Haskell-cafe] Well typed OS

Hi Yotam, one rather small and abstract comment: Permissions and capabilities feel like they are something contravariant. Intuitively it should be easy to "get out" of permissions but hard to "get into" them. (compare 'pure' and 'extract') Resulting actions are probably covariant just like the more general IO. Therefore I conclude that programs in your OS will probably be a profunctor, an arrow, or something similar. I wouldn't even be surprised if one could build an OS on nothing but Optics into the RealWorld. Cheers, MarLinn