Cyclone is a polymorphic, type-safe programming language derived from C. The primary design goals of Cyclone are to let programmers control data representations and memory management without sacrificing type-safety. In this paper, we focus on the region-based memory management of Cyclone and its static typing discipline. The design incorporates several advancements, including support for region subtyping and a coherent integration with stack allocation and a garbage collector. To support...