Ferrite: A Judgmental Embedding of Session Types in Rust

TL;DR

Ferrite is a Rust library that embeds session types, supporting linear and shared types, enabling safe communication by encoding typing derivations as Rust functions with practical evaluation on Servo.

Contribution

Ferrite introduces a novel shallow embedding of session types in Rust that supports shared session types and encodes typing derivations as Rust functions.

Findings

Supports linear and shared session types in Rust

Successfully applied to safe communication in Servo

Demonstrates practical feasibility of session types in Rust

Abstract

This paper introduces Ferrite, a shallow embedding of session types in Rust. In contrast to existing session type libraries and embeddings for mainstream languages, Ferrite not only supports linear session types but also shared session types. Shared session types allow sharing (aliasing) of channels while preserving session fidelity (preservation) using type modalities for acquiring and releasing sessions. Ferrite adopts a propositions as types approach and encodes typing derivations as Rust functions, with the proof of successful type-checking manifesting as a Rust program. We provide an evaluation of Ferrite using Servo as a practical example, and demonstrate how safe communication can be achieved in the canvas component using Ferrite.