Deadlock-free Context-free Session Types

Andreia Mordido; Jorge A. Pérez

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arXiv · 2506.20356

Deadlock-free Context-free Session Types

Andreia Mordido·Jorge A. Pérez

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Abstract

We tackle the problem of statically ensuring that message-passing programs never run into deadlocks. We focus on concurrent functional programs governed by context-free session types, which can express rich tree-like structures not expressible in standard session types. We propose a new type system based on context-free session types: it enforces both protocol conformance and deadlock freedom, also for programs implementing cyclic communication topologies with recursion and polymorphism. We show how the priority-based approach to deadlock freedom can be extended to this expressive setting. We prove that well-typed concurrent programs respect their protocols and never deadlock.

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Andreia Mordido, Jorge A. Pérez. 2025-06-25. Deadlock-free Context-free Session Types. https://arxiv.org/abs/2506.20356

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