Language Based Verification Tools for Functional Programs (Dagstuhl Seminar 16131)

This report documents the program and the outcomes of Dagstuhl Seminar 16131 "Language Based Verification Tools for Functional Programs". This seminar is motivated by two converging trends in computing -- the increasing reliance on software has led to an increased interest in seeking formal, reliable means of ensuring that programs possess crucial correctness properties, and the dramatic increase in adoption of higher-order functional languages due to the web, multicore and "big data" revolutions. While the research community has studied the problem of language based verification for imperative and first-order programs for decades – yielding important ideas like Floyd-Hoare Logics, Abstract Interpretation, Model Checking, and Separation Logic and so on – it is only relatively recently, that proposals have emerged for language baseverification tools for functional and higher-order programs. These techniques include advanced type systems, contract systems, model checking and program analyses specially tailored to exploit the structure of functional languages. These proposals are from groups based in diverse research communities, attacking the problem from different angles, yielding techniques with complementary strengths. This seminar brought diverse set of researchers together so that we could: compare the strengths and limitations of different approaches, discuss ways to unify the complementary advantages of different techniques, both conceptually and in tools, share challenging open problems and application areas where verification may be most effective, identify novel ways of using verification techniques for other software engineering tasks such as code search or synthesis, and improve the pedagogy and hence adoption of such techniques.