Towards Lightweight and Efficient Choreographic Cloud Services

Paper i proceeding, 2026

Choreographic programming provides a high-level abstraction for writing distributed computations while ensuring deadlock-freedom by construction. HasChor, a Haskell-based choreographic programming framework, offers a practical implementation of these ideas but faces limitations in handling an arbitrary number of participants and optimizing the communication of branches. In this work, we introduce CloudChor, a set of extensions that enhance HasChor's expressiveness and efficiency through the use of multiply-located values, allowing choreographies to distribute and collect data across multiple participants in a structured manner. Additionally, we refine HasChor's branching mechanism through a lightweight static analysis, selectively propagating branching decisions only to relevant participants, reducing communication overhead. To strengthen theoretical guarantees, we establish a formal semantics for HasChor and our extensions, proving deadlock-freedom. Finally, we demonstrate the practicality of our enhancements by implementing a data clean room protocol using CloudChor. Our contributions improve the applicability of choreographic programming to cloud-based secure data collaborations, making it a stronger candidate for real-world deployments.