Abstract

Embedded computer systems seem to be the antithesis of functional language systems. Embedded systems are small, stand-alone, and are often forced to accept inelegant design compromises due to hardware cost. They run continuously and are reactive, that is, their primary goal is to monitor sensors and control effectors, using observed external events to trigger state-changing control actions. Yet this paper describes how functional abstraction can tame the inelegance of embedded systems. Architectural compromises can be made in device drivers, programmed within the functional language, but a function-level interface is presented to the application programmer. Examples are given from a liftshaft case study. 1 Introduction Programming an embedded system requires certain features to be present in the chosen programming language and environment. It must be possible: # to write detailed device-driving code; # to deal promptly with asynchronous events (interrupts) ; # to ensure that the s...

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