chapter g

I discuss separation logic basics some more, as presented in the seminal paper by John C. Reynolds.  An important idea is describing data structure using separating conjunction and recursive predicates.

I discuss separation logic, as presented in this seminal paper by the great John C. Reynolds.  I did not go very far into the topic, so please expect a follow-up episode.

In this episode, I talk briefly about Rust, which uses compile-time analysis to ensure that code is memory-safe (and also free of data races in concurrent code) without using a garbage collector.  Fantastic!  The language draws on but richly develops ideas on ownership that originated in academic research.

I discuss the idea of statically typed region-based memory management, proposed by Tofte and Talpin.  The idea is to allow programmers to declare explicitly the region from which to satisfy individual allocation requests.  Regions are created in a statically scoped way, so that after execution leaves the body of the region-creation construct, the entire region may be deallocated.  Type inference is used to make sure that no dangling pointers are dereferenced (after the associated region is deallocated).  This journal paper about the idea is not easy reading, but has a lot of good explanations in and around all the technicalities.  Even better, I found, is this paper about region-based memory management in Cyclone.  There are lots of intuitive explanations of the ideas, and not so much gory technicality.

In this episode, I start a new chapter (we are up to Chapter 16, here), about verifying safe manual management of memory.  I have personally gotten pretty interested in this topic, having seen through some simple experiments with Haskell how much time can go into garbage collection for seemingly simple benchmarks.  I also talk about why verifying memory-usage properties of programs is challenging in proof assistants.