From Seo Wiki - Search Engine Optimization and Programming Languages
Spec# is a programming language with specification language features that extends the capabilities of the C# programming language with Eiffel-like contracts, including object invariants, preconditions and postconditions. Like ESC/Java, it includes a static checking tool based on a theorem prover that is able to statically verify many of these invariants. It also includes a variety of other minor extensions to the language, such as non-null reference types.
Microsoft Research developed both Spec# and C#; in turn, Spec# serves as the foundation of the Sing# programming language, which Microsoft Research also developed.
This example shows two of the basic structures that are used when adding contracts to your code.
static void Main(string! args)
requires args.Length > 0
foreach(string arg in args)
- ! is used to make a reference type non-nullable, e.g. you cannot set the value to null. This in contrast of nullable types which allows value types to be set as null.
- requires indicates a condition that must be followed in the code. In this case the length of args is not allowed to be zero or less.
- Barnett, M., K. R. M. Leino, W. Schulte, "The Spec# Programming System: An Overview." Proceedings of Construction and Analysis of Safe, Secure and Interoperable Smart Devices (CASSIS), Marseilles. Springer-Verlag, 2004.