Doc No: N4378 Date: 2015-02-08

Language Support for Contract Assertions (Revision 10) With enough care we can build libraries that are essentially defect-free, but even the best library may fail catastrophically when misused. Contract validation, the practice of checking functions ' preconditions when and where they are called, helps discover misuse at compile time or in early testing, speeding development and making software more robust. We propose here complete Working Paper text defining simple facilities to help library developers, application developers, and language implementers cooperate toward our common goal of delivering efficient programs without defects. Library developers get a common framework to express the contracts offered by their library functions, without compromising performance or interface simplicity. Application developers get the option to specify, without reference to details of the libraries they use, how much run time to spend on validation, and precisely what to do when a violation is detected. Implementations get permission and encouragement to infer programmers&apos