How do you dynamically customize the programming language available in a context within an existing system, without changing the underlying system? This dissertation introduces a language design approach that addresses this problem. The basic idea is to structure programs as systems of multiple interacting levels of abstraction, where all of the…

Over the past several decades, millions of digital objects of significant scientific, economic, cultural, and historic value have been published and distributed to libraries and archives on removable media. Providing long-term access to these documents, media files, and software executables is an increasingly complex task because of dependencies…