Teaching Design by Contract using Snap!
This work addresses the challenge of teaching design-by-contract reasoning to a broader audience, such as high school students, but is incremental as it adapts existing verification techniques to a visual programming environment.
The paper tackled the problem of making deductive program verification accessible to non-experts, particularly high school students, by developing visual specification and verification support for the Snap! programming language, resulting in both static and dynamic verification capabilities with intuitive error messaging.
With the progress in deductive program verification research, new tools and techniques have become available to support design-by-contract reasoning about non-trivial programs written in widely-used programming languages. However, deductive program verification remains an activity for experts, with ample experience in programming, specification and verification. We would like to change this situation, by developing program verification techniques that are available to a larger audience. In this paper, we present how we developed prototypal program verification support for Snap!. Snap! is a visual programming language, aiming in particular at high school students. We added specification language constructs in a similar visual style, designed to make the intended semantics clear from the look and feel of the specification constructs. We provide support both for static and dynamic verification of Snap! programs. Special attention is given to the error messaging, to make this as intuitive as possible.