Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2509.04253

When Lifetimes Liberate: A Type System for Arenas with Higher-Order Reachability Tracking

Siyuan He·Songlin Jia·Yuyan Bao·Tiark Rompf
View original source ↗Read source document ↗Export metadata ↓

Abstract

Static resource management in languages remains challenging due to tensions among control, expressiveness, and flexibility. Region-based systems [Grossman et al . 2002; Tofte et al. 2001] offer bulk deallocation via lexically scoped regions, where all allocations follow a stack discipline. However, both regions and their resources are second-class, and neither can escape its scope nor be freely returned. Ownership and linear type systems, exemplified by Rust [Clarke et al. 2013], offer non-lexical lifetimes and robust static guarantees, but rely on invariants that limit higher-order patterns and expressive sharing. In this work, we propose a new type system that unifies these strengths. Our system treats all heap-allocated resources as first-class values, while allowing programmers to control lifetime and granularity through three allocation modes: (1) fresh allocation for individual, non-lexical references; (2) subsequent coallocation grouping resources collectively within shadow arenas; and (3) scoped allocation with lexically bounded lifetimes following stack discipline. Regardless of mode, all resources share a uniform type and have no distinction for generic abstractions, preserving the higher-order parametric nature of the language. Obtaining static safety in higher-order languages with flexible sharing is nontrivial. We address this by extending reachability types [Wei et al. 2024] to collectively track first-class resources, and by adopting flow-insensitive deallocation reasoning for selective stack discipline. These mechanisms yield Aq<: and {A}q<: atop, both formalized and proven type safe and memory safe in Rocq.

Explore related subjects

cs.PL

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Siyuan He, Songlin Jia, Yuyan Bao, Tiark Rompf. 2026-03-28. When Lifetimes Liberate: A Type System for Arenas with Higher-Order Reachability Tracking. https://arxiv.org/abs/2509.04253

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Expressive power of one-shot control operators and coroutines

Control operators, such as exceptions and effect handlers, provide a means of representing computational effects in programs abstractly and modularly. While most theoretical studies have focused on multi-shot control operators, one-shot control operators---which restrict the use of captured continuations to at most once---are gaining attention for their balance between expressiveness and efficiency. This study aims to fill the gap. We present a mathematically rigorous comparison of the expressive power among one-shot control operators, including effect handlers, delimited continuations, and even asymmetric coroutines. Following previous studies on multi-shot control operators, we adopt Felleisen's macro-expressiveness as our measure of expressiveness. We verify the folklore that one-shot effect handlers and one-shot delimited-control operators can be macro-expressed by asymmetric coroutines, but not vice versa. We explain why a previous informal argument fails, and how to revise it to make a valid macro-translation.

cs.PL↗
arXiv2026

Authorization Revocation for Long-Running AI Agents: Root-Scoped Quiescence under Delegation and Asynchronous Execution

Long-running AI agents outlive initiating processes through credentials, delegated tasks, queues, callbacks, reservations, and provider-side operations. Cancellation, process exit, and credential revocation neither close every pre-cut carrier nor distinguish independently authorized shared work. We define root-scoped authorization quiescence: for each manifested sink, a certificate accounts for every cut-relevant acceptance under the retired root-epoch atom that precedes its local fence and excludes protected acceptance under that atom after the fence, while permitting exact rebind to a current, independently sufficient support. The root-scoped quiescence protocol linearizes a root cut, fences old-root expansion and protected sinks, represents alternative and conjunctive authority as antichains of minimal sufficient root sets, and composes provider-frontier certificates into a cutset over registered old-root paths. Exact channel-token accounting reconciles transfers; missing or conflicting evidence remains indeterminate. Under stated assumptions, we prove post-cut issuer non-expansion, support-sound projection, compositional soundness under exact channel conservation, independent-support preservation, merge-order independence, and crash/replay stability. A provider-free late-effect test suite matches 17/17 registered outcomes. Two cancellation-only and one cut-only execution accept the same class of already scheduled late effect; two cut-plus-fence executions, one restart, and one stale-process execution reject it. A separately implemented checker verifies 17/17 traces and rejects 44/44 consistently rehashed semantic regressions. The certificate establishes root-relative authorization quiescence within its bound manifest and configuration, not global idleness, rollback, or business completion.

cs.PL↗
arXiv2026

Soda: An Object-Oriented Functional Language for Specifying Human-Centered Problems

We present Soda (Symbolic Objective Descriptive Analysis), a language that helps to treat qualities and quantities in a natural way and greatly simplifies the task of checking correctness. We present key properties for the language motivated by the design of a descriptive language to encode complex requirements on computer systems, and we explain how these key properties must be addressed to model these requirements with simple definitions. We give an overview of a tool that helps to describe problems in an easy way, which we consider more transparent and less error-prone.

cs.PL↗