A formal soundness proof of region-based memory management for object-oriented paradigm.

Region-based memory management has been proposed as a viable alternative to garbage collection for real-time applications and embedded software. In our previous work we have developed a region type inference algorithm that provides an automatic compile-time region-based memory management for object-oriented paradigm. In this work we present a formal soundness proof of the region type system that is the target of our region inference. More precisely, we prove that the object-oriented programs accepted by our region type system achieve region-based memory management in a safe way. That means, the regions follow a stack-of-regions discipline and regions deallocation never create dangling references in the store and on the program stack. Our contribution is to provide a simple syntactic proof that is based on induction and follows the standard steps of a type safety proof. In contrast the previous safety proofs provided for other region type systems employ quite elaborate techniques

Syntactic Type Soundness Results for the Region Calculus

The region calculus of Tofte and Talpin is a polymorphically typed lambda calculus with annotations that make memory allocation and deallocation explicit. It is intended as an intermediate language for implementing ML without garbage collection. Static region and eect inference can be used to generate annotations from a given ML program. Soundness of the calculus with respect to the region and eect system is crucial to guarantee safe deallocation of regions, i.e., deallocation should only take place for objects which are provably dead. The original soundness proof by Tofte and Talpin requires a complex co-inductive safety relation. In this paper, we present two small-step operational semantics for the region calculus and prove their soundness. Following the syntactic approach of Wright, Felleisen, and Harper, we obtain simple inductive proofs. The rst semantics is store-less. It is simple and elegant and gives rise to perspicuous proofs. The second semantics provides a store-based model for the region calculus. It is slightly more complicated, but includes operations on references with destructive update. We prove (the pure fragment of) both semantics equivalent to the original evaluation-style formulation by Tofte and Talpin

Polymorphic specialization for ML

We present a framework for offline partial evaluation for call-by-value functional programming languages with an ML-style typing discipline. This includes a binding-time analysis which is (1) polymorphic with respect to binding times; (2) allows the use of polymorphic recursion with respect to binding times; (3) is applicable to a polymorphically typed term; and (4) is proven correct with respect to a novel small-step specialization semantics. The main innovation is to build the analysis on top of the region calculus of Tofte and Talpin, thus leveraging the tools and techniques developed for it. Our approach factorizes the binding-time analysis into region inference and a subsequent constraint analysis. The key insight underlying our framework is to consider binding times as properties of regions. Specialization is specified as a small-step semantics, building on previous work on syntactic type soundness results for the region calculus. Using similar syntactic proof techniques, we prove soundness of the binding-time analysis with respect to the specializer. In addition, we prove that specialization preserves the call-by-value semantics of the region calculus by showing that th