Functional programming for operating systems : the purely functional implementation of input/output

The potential advantages of Functional Programming (FP) have lead to the successful development of numerous application programs such as editors and command interpreters [8,11]. This thesis explores how FP can be applied to systems programming while focussing on the implementation of input and output as well as related issues such as preemption and queueing. It will be determined to what extent non-functional support is needed to build a link between the temporal, and generally non-functional behavior of the underlying computer hardware, and the timeless character of the mathematical definitions that represent the software level. The notion of mathematical fictitious streams and functions is introduced and used to formulate hardware behavior functionally. It is the overall objective of this feasibility study to explore implementation strategies for delayed evaluated streams that minimize the amount of non-functional code, while preserving referential transparency. A simple, disk based inventory system is used to discuss the feasibility of different approaches for handling synchronous and asynchronous streams including nil-insertion (which Turner calls "hiaton streams" [18]) and time stamping of stream elements.