Formal Reasoning Using an Iterative Approach with an Integrated Web IDE
This addresses the problem of teaching formal methods in software engineering education, though it is incremental as it builds on existing design-by-contract principles.
The paper tackles teaching formal reasoning for software correctness by using a specialized Web IDE with a verifying compiler, showing that learners iteratively develop provable code through feedback on verification conditions. Classroom examples demonstrate how the IDE helps refine assertions like loop invariants in object-based code.
This paper summarizes our experience in communicating the elements of reasoning about correctness, and the central role of formal specifications in reasoning about modular, component-based software using a language and an integrated Web IDE designed for the purpose. Our experience in using such an IDE, supported by a 'push-button' verifying compiler in a classroom setting, reveals the highly iterative process learners use to arrive at suitably specified, automatically provable code. We explain how the IDE facilitates reasoning at each step of this process by providing human readable verification conditions (VCs) and feedback from an integrated prover that clearly indicates unprovable VCs to help identify obstacles to completing proofs. The paper discusses the IDE's usage in verified software development using several examples drawn from actual classroom lectures and student assignments to illustrate principles of design-by-contract and the iterative process of creating and subsequently refining assertions, such as loop invariants in object-based code.