A Generic Programming Toolkit for PADS/ML: First-Class Upgrades for Third-Party Developers

Domain-specific languages facilitate solving problems in a targeted domain by providing features particular to the domain. Declarative domain-specific languages have the additional benefit that users specify what something means rather than how to do something. As a result, the language compiler is free to choose the best implementation strategies and to generate multiple artifacts from a single description. pads/ml is a declarative data description language designed to facilitate ad hoc data management. From a single description, the compiler generates a myriad of artifacts, including data structures for the in-memory representation of the data and parsers and printers. In this paper, we describe a new generic programming infrastructure for pads/ml that allows third-party developers to define additional useful artifacts without modifying the compiler. We report on two case studies that use this infrastructure. In the first, we build a version of padx for pads/ml, allowing any data source with a pads/ml description to be queried as if it were xml. In the second, we extend Harmony with the ability to synchronize any data with a pads/ml description.