Multi-stage programming (MSP) provides a disciplined approach to run-time code generation. In the purely functional setting, it has been shown how MSP can be used to reduce the overhead of abstractions, allowing clean, maintainable code without paying performance penalties. Unfortunately, MSP is difficult to combine with imperative features, which are prevalent in mainstream languages. The central difficulty is scope extrusion, wherein free variables can inadvertently be moved outside the scopes of their binders. This paper proposes a new approach to combining MSP with imperative features that occupies a "sweet spot" in the design space in terms of how well useful MSP applications can be expressed and how easy it is for programmers to understand. The key insight is that escapes (or "anti-quotes") must be weakly separable from the rest of the code, i.e. the computational effects occurring inside an escape that are visible outside the escape are guaranteed to not contain code. To demonstrate the feasibility of this approach, we formalize a type system based on Lightweight Java which we prove sound, and we also provide an implementation, called Mint, to validate both the expressivity of the type system and the effect of staging on the performance of Java programs.

Concurrent programming is becoming more important due to the growing dominance of multi-core processors and the prevalence of graphical user interfaces (GUIs). To prepare students for the concurrent future, instructors have begun to address concurrency earlier in their curricula. Unfortunately, test-driven development, which enables students and practitioners to quickly develop reliable single-threaded programs, is not as effective in the domain of concurrent programming. This paper describes how ConcJUnit can simplify the task of writing unit tests for multi-threaded programs, and provides examples that can be used to introduce students to concurrent programming.

We provide a systematic transformation of an LL(1) grammar to an object model that consists of

We specify and implement a GUI application that simulates marine biological systems by making extensive use of object-oriented design patterns.The key design patterns are model-view-control, observer/observable, visitor, command, factory method and decorator. These design patterns help delineate the roles and responsibilities of the objects in the system, establish loose coupling between objects and arrange for the objects to communicate and cooperate with one another at the highest level of abstraction. The result is an application that exhibits minimal control flow, yet is powerful, robust, flexible and easy to maintain.Our work entails a non-trivial redesign of the current AP Computer Science Marine Biology Simulation case study and may serve as a case study for an introductory "object-first" curriculum.