Design By Contact Approach: Spec#

I recently attended a very interesting presentation by Matt Podwysocki
where he talked about Spec#.  This is an extension to the C# language
that implements the DBC (Design By Contract) approach to development. 
Spec# was developed by Microsoft Research and you can find more
information about it here.  It is really some very interesing stuff that will hopefully be implemented in the future releases of C#/.NET.

Matt
has put a lot of effort into understanding and explaining the details
of DBC.  Here are the links to his posts on the subject:

Spec# Part 1

Spec# Part 2

Spec# Part 3

Spec# Part 4

Spec# Part 5

Spec# Part 6

Spec# Part 7