A modal language for the safety of mobile values

We present a modal language for distributed computation which addresses the safety of mobile values as well as mobile code. The safety of mobile code is achieved with the modality � which corresponds to necessity of modal logic. For the safety of mobile values, we introduce a new modality ○ which expresses that given code evaluates to a mobile value. We demonstrate the use of modal types with three communication constructs: remote evaluation, futures, and asynchronous channels