Abstract. This chapter describes Hume: a functionally-based language for programming with bounded resource usage, including time and space properties. The purpose of the Hume language design is to explore the expressibility/costability spectrum in resource-constrained systems, such as real-time embedded or control systems. It is unusual in being based on a combination of λ-calculus and finite state machine notions, rather than the more usual propositional logic, or flat finite-state-machine models. The use of a strict, purely functional programming notation allows the construction of a strong cost model for expressions, which can then be embedded into a simple cost model for processes. In this chapter, we introduce Hume, describe the Hume Abstract Machine implementation, and show how a high-level cost model can be constructed that relates costs from the abstract machine to Hume source programs. We illustrate our approach with an example adapted from the literature: a simple vending machine controller. 1

Abstract—We construct a fully automatic static WCET analysis suitable for real-time embedded systems applications by augmenting a high-level static analysis technique (originally aimed at heap-space) with a machine-level worst-case execution time tool. We evaluate this approach by studying two typical and realistic real-time control applications, using a readily available commercial microcontroller. Keywords-WCET; analysis; static; type system; I.

analysis to imperative programs with pointers