Research Areas
Functional programming, end-user programming, visual languages, domain-specific languages

Research Description
My research centers around the design of languages, in particular, typed functional languages. This is not restricted to functional programming languages, but also includes visual/end-user languages and query languages. Since the functional programming paradigm is based on the mathematical notion of a function, functional languages enjoy many nice properties, such as referential transparency, which makes it much easier to reason about functional programs than about programs written in imperative or object-oriented languages. Some benefits of this aspect are that functional programs tend to contain less errors than imperative ones and that they can be developed in a fraction of the time needed for corresponding imperative programs.

There are two major areas of research. The first area centers around the design and application of functional programming languages. One example is the application of functional programming to graph algorithms. We have developed an inductive view of graphs that allows the formulation of graph algorithms in a high-level recursive style, which frees graph algorithms from the need of performing low-level node markings. Another example is the design of type-safe updates and type-safety-preserving update languages that support software maintenance by providing a systematic and reliable way of performing software updates.

The second area is concerned with the application of the functional modeling approach to the design of other languages. For example, we have developed functional data models and query languages for spatial and spatiotemporal data whose expressiveness and simplicity result from their functional design. Other examples of applications include a visual query language for XML, a type system for spreadsheets, and a semantics formalism for visual languages.