Lisp and Scheme have demonstrated the power of macros to enable programmers to evolve and craft languages. In languages with more complex syntax, macros have had less success. In part, this has been due to the difficulty in building expressive hygienic macro systems for such languages. JavaScript in particular presents unique challenges for macro systems due to ambiguities in the lexing stage that force the JavaScript lexer and parser to be intertwined.

JavaScript's typed arrays have proven to be a crucial API for many JS applications, particularly those working with large amounts of data or emulating other languages. Unfortunately, the current typed array API offers no means of abstraction. Programmers are supplied with a simple byte buffer that can be viewed as an array of integers or floats, but nothing more.

We present Dependent JavaScript (DJS), a statically typed dialect of the imperative, object-oriented, dynamic language. DJS supports the particularly challenging features such as run-time type-tests, higher-order functions, extensible objects, prototype inheritance, and arrays through a combination of nested refinement types, strong updates to the heap, and heap unrolling to precisely track prototype hierarchies. With our implementation of DJS, we demonstrate that the type system is expressive enough to reason about a variety of tricky idioms found in small examples drawn from several sources, including the popular book JavaScript: The Good Parts and the SunSpider benchmark suite.

Filinski showed that callcc and a single mutable reference cell are sufficient to express the delimited control operators shift and reset. However, this implementation interacts poorly with dynamic bindings like exception handlers. We present a variation on Filinski's encoding of delimited continuations that behaves appropriately in the presence of exceptions and give an implementation in Standard ML of New Jersey. We prove the encoding correct with respect to the semantics of delimited dynamic binding.