Abstract. X10 is a modern object-oriented language designed for productivity and performance in concurrent and distributed systems. In this setting, dependent types offer significant opportunities for detecting design errors statically, documenting design decisions, eliminating costly runtime checks (e.g., for array bounds, null values), and improving the quality of generated code. We present the design and implementation of constrained types, a natural, simple, clean, and expressive extension to object-oriented programming: A type C(:c) names a class or interface C and a constraint c on the immutable state of C and in-scope final variables. Constraints may also be associated with class definitions (representing class invariants) and with method and constructor definitions (representing preconditions). Dynamic casting is permitted. The system is parametric on the underlying constraint system: the compiler supports a simple equalitybased constraint system but, in addition, supports extension with new constraint systems using compiler plugins. 1

The increased importance of XML as a universal data representation format has led to several proposals for enabling the development of applications that operate on XML data. These proposals range from runtime API-based interfaces to XML-based programming languages. The subject of this paper is XJ, a research language that proposes novel mechanisms for the integration of XML as a first-class construct into Java. The design goals of XJ distinguish it from past work on integrating XML support into programming languages --- specifically, the XJ design adheres to the XML Schema and XPath standards, and supports in-place updates of XML data thereby keeping with the imperative nature of Java. We have also built a prototype compiler for XJ, and our preliminary experimental results demonstrate that the performance of XJ programs can approach that of traditional low level API-based interfaces, while providing a higher level of abstraction.

Abstract—Soot is a successful framework for experimenting with compiler and software engineering techniques for Java programs. Researchers from around the world have implemented a wide range of research tools which build on Soot, and Soot has been widely used by students for both courses and thesis research. In this paper, we describe relevant features of Soot, summarize its development process, and discuss useful features for future program analysis frameworks. I.