Naive program transformations can have surprising effects due to the interaction between introduced identifier references and previously existing identifier bindings, or between introduced bindings and previously existing references. These interactions can result in the inadvertent binding, or capturing, of identifiers. A further complication results from the fact that the transformed program may have little resemblance to the original program, making correlation of source and object code difficult. We address both the capturing problem and the problem of source-object code correlation. Previous approaches to the capturing problem have been both inadequate and overly restrictive, and the problem of source-object code correlation has been largely unaddressed. Our approach is based on a new algorithm for implementing syntactic transformations...

Abstract not found

Separate compilation is an important tool for coping with design complexity in large software projects. When done right it can also be used to create software libraries, thus promoting code reuse. But separate compilation comes in various flavors and has many facets: namespace management, linking, optimization, dependencies. Many programming languages identify modular units with units of compilation, while only a few extend this to permit hierarchies of language-level modules within individual compilation units. When the number of compilation units is large, then it becomes increasingly important that the mechanism of separate compilation itself can be used to control namespaces. The group model implemented in SML/NJ's compilation manager CM provides the necessary facilities to avoid unwanted interferences between unrelated parts of large programs. Compilation units are arranged into groups, and explicit export interfaces can be used to control namespaces. When there are many groups, t...

This paper describes an alternative to the low-level macro facility described in the Revised

I have been hearing some complaints that Scheme's new lexically scoped macro facility is difficult to implement. There are two components to the proposal: the pattern language, and lexical scoping. The two pose independent problems. I agree that the ellipsis-enriched pattern language can be tricky to implement; implementations that I have seen take anywhere from 250 to 1400 lines of Scheme code. However, I believe that it is conceptually straightforward, and several implementations have been around for many years (see [9]). On the other hand, many people are unnecessarily getting tripped up on lexical scoping, which, unlike the pattern matcher, is very simple to implement.