Abstract

In a pure functional language like Clean the values of the functional variables are constants; variables of functional programs do not change in time. Hence it seems that temporality has no meaning in functional programs. However, in certain cases (e.g. in interactive or distributed programs, or in ones that use IO) we would like to consider a series of values object we can already prove temporal properties (e.g. invariants). In this paper we present a case study: our example is an interactive database with some simple operations like updating, sorting, querying records. We specify an invariant property of our program and we show how to prove this property. We utilize Sparkle, a theorem prover designed for the Clean language. Since Sparkle is not capable of handling temporal logical properties, the application of certain rules of the proof system are performed by hand. This way we simulate the behaviour of a more sophisticated theorem prover, which is currently under development.

Citations