Spectur | A Speci cation Language for the Programmer

Spectur (Speci cation language after Turing) has been designed as a language for formal speci cation. The goals of the language include: ease of use by a speci er to write a software system speci cation from an informal description; ease of use by an implementor to build a program from a speci cation; ease of understanding by a user as documentation; ease of use by a mathematician to prove program correctness. The Spectur method of specifying a programmodule consists of declaring abstracted data structures, and specifying the procedures and functions of the module in terms of preand post-conditions on those data structures. Spectur is notable for providing notation and data structures that are both mathematically precise and immediately recognizable by programmers. A non-trivial example speci cation of a small operating system has been done using Spectur. We discuss this example, as well as the usefulness and potential applications of Spectur. 1 Formal Speci cation and Spectur The importance of speci cation is understood well by the software engineering community. Speci cations are useful both at the design stage of software development, to help to clarify and to decompose the problem, and later as documentation and as an aid in proving program correctness. A central aim