Stepwise refinement of heap-manipulating code in Chalice

Stepwise refinement is a well-studied technique for developing a program from an abstract description to a concrete implementation. This paper describes a system with automated tool support for refinement, powered by a state-of-the-art verification engine that uses an SMT solver. Unlike previous refinement systems, users of the presented system interact only via declarations in the programming language. Another aspect of the system is that it accounts for dynamically allocated objects in the heap, so that data representations in an abstract program can be refined into ones that use more objects. Finally, the system uses a language with familiar imperative features, including sequential composition, loops, and recursive calls, offers a syntax with skeletons for describing program changes between refinements, and provides a mechanism for supplying witnesses when refining non-deterministic programs

Data-driven synthesis for object-oriented frameworks

Software construction today often involves the use of large frameworks. The challenge in this type of programming is that object-oriented frameworks tend to grow exceedingly intricate; they spread functionality among numerous classes, and any use of the framework requires knowledge of many interacting components. We present a system named MATCHMAKER that from a simple query synthesizes code that interacts with the framework. The query consists of names of two framework classes, and our system produces code enabling interaction between them. MATCHMAKER relies on a database of dynamic program traces called DELIGHT that uses novel abstraction-based indexing techniques to answer queries about the evolution of heap connectivity in a matter of seconds. The paper evaluates the performance and effectiveness of MATCHMAKER on a number of benchmarks from the Eclipse framework. The paper also presents the results of a user study that showed a 49% average productivity improvement from the use of our tool.National Science Foundation (U.S.). (Grant number CCF-1049406)Massachusetts Institute of Technology. Computer Science and Artificial Intelligence Laborator

Unifying Execution of Imperative and Declarative Code

We present a unified environment for running declarative specifications in the context of an imperative object-Oriented programming language. Specifications are Alloy-like, written in first-order relational logic with transitive closure, and the imperative language is Java. By being able to mix imperative code with executable declarative specifications, the user can easily express constraint problems in place, i.e., in terms of the existing data structures and objects on the heap. After a solution is found, the heap is updated to reflect the solution, so the user can continue to manipulate the program heap in the usual imperative way. We show that this approach is not only convenient, but, for certain problems can also outperform a standard imperative implementation. We also present an optimization technique that allowed us to run our tool on heaps with almost 2000 objects

Deriving divide-and-conquer dynamic programming algorithms using solver-aided transformations

We introduce a framework allowing domain experts to manipulate computational terms in the interest of deriving better, more efficient implementations.It employs deductive reasoning to generate provably correct efficient implementations from a very high-level specification of an algorithm, and inductive constraint-based synthesis to improve automation. Semantic information is encoded into program terms through the use of refinement types. In this paper, we develop the technique in the context of a system called Bellmania that uses solver-aided tactics to derive parallel divide-and-conquer implementations of dynamic programming algorithms that have better locality and are significantly more efficient than traditional loop-based implementations. Bellmania includes a high-level language for specifying dynamic programming algorithms and a calculus that facilitates gradual transformation of these specifications into efficient implementations. These transformations formalize the divide-and conquer technique; a visualization interface helps users to interactively guide the process, while an SMT-based back-end verifies each step and takes care of low-level reasoning required for parallelism. We have used the system to generate provably correct implementations of several algorithms, including some important algorithms from computational biology, and show that the performance is comparable to that of the best manually optimized code.National Science Foundation (U.S.) (CCF-1139056)National Science Foundation (U.S.) (CCF- 1439084)National Science Foundation (U.S.) (CNS-1553510

Program synthesis from execution traces and demonstrations

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.Cataloged from PDF version of thesis.Includes bibliographical references (pages 116-121).In this thesis, we introduce an architecture for programming productivity tools that relies on a database of execution traces. Our database enables a novel user interaction model for a programmer assistant based on short demonstrations of framework usages in applications. By matching the demonstration traces against the complete traces in the database, our system infers the code snippets for the demonstrated feature including the missing set-up steps. We develop techniques for an interactive trace matching process, and evaluate them on a sample of Swing applications. We show that our system synthesizes code for several features of the Eclipse platform from traces of existing Eclipse plug-ins, and that the generated code is comparable in quality to the tutorial code.by Kuat Yessenov.Ph. D

Lightweight specification language for Java amenable to bounded analysis

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 63-64).This thesis presents a new light-weight specification language called JForge Specification Language (JFSL) for object-oriented languages such as Java. The language is amenable to bounded verification analysis by a tool called JForge that interprets JFSL specifications, fully integrates with a mainstream development environment, and assists programmers in examining counter example traces and debugging specifications. JFSL attempts to address challenges of specification languages such as inheritance, frame conditions, dynamic dispatch, and method calls inside specifications in the context of bounded verification. A collection of verification tasks illustrates the expressiveness and conciseness of JForge specifications and demonstrates effectiveness of the bounded verification technique.by Kuat T. Yessenov.M.Eng