Abstract
This paper presents techniques and tools to transform spreadsheets into relational databases and back. A set of data refinement rules is introduced to map a tabular datatype into a relational database schema. Having expressed the transformation of the two data models as data refinements, we obtain for free the functions that migrate the data. We use well-known relational database techniques to optimize and query the data. Because data refinements define bidirectional transformations we can map such database back to an optimized spreadsheet. We have implemented the data refinement rules and we constructed HASKELL-based tools to manipulate, optimize and refactor Excel-like spreadsheets. ©2009 ACM.

Abstract
Circular programs are a powerful technique to express multiple traversal algorithms as a single traversal function in a lazy setting. In this paper, we present a shortcut deforestation technique to calculate circular programs. The technique we propose takes as input the composition of two functions, such that the first builds an intermediate structure and some additional context information which are then processed by the second one, to produce the final result. Our transformation into circular programs achieves intermediate structure deforestation and multiple traversal elimination. Furthermore, the calculated programs preserve the termination properties of the original ones.

Abstract
This paper presents techniques to model circular lazy programs in a strict, purely functional setting. Circular lazy programs model any algorithm based on multiple traversals over a recursive data structure as a single traversal function. Such elegant and concise circular programs are defined in a (strict or lazy) functional language and they are transformed into efficient strict and deforested, multiple traversal programs by using attribute grammars-based techniques. Moreover, we use standard slicing techniques to slice such circular lazy programs. We have expressed these transformations as an Haskell library and two tools have been constructed: the HaCirc tool that refactors Haskell lazy circular programs into strict ones, and the OCirc tool that extends Ocaml with circular definitions allowing programmers to write circular programs in Ocaml notation, which are transformed into strict Ocaml programs before they are executed. The first benchmarks of the different implementations are presented and show that for algorithms relying on a large number of traversals the resulting strict, deforested programs are more efficient than the lazy ones, both in terms of runtime and memory consumption. Copyright © 2007 ACM.

Abstract
This tool demo paper presents SmellSheet Detective: a tool for automatically detecting bad smells in spreadsheets. We have defined a catalog of bad smells in spreadsheet data which was fully implemented in a reusable library for the manipulation of spreadsheets. This library is the building block of the SmellSheet Detective tool, that has been used to detect smells in large, real-world spreadsheets within the EUSES corpus, in order to validate and evolve our bad smells catalog.

Abstract
In this paper we explore the use of models in the context of spreadsheet engineering. We review a successful spreadsheet modeling language, whose semantics we further extend. With this extension we bring spreadsheet models closer to the business models of spreadsheets themselves. An addon for a widely used spreadsheet system, providing bidirectional model-driven spreadsheet development,

Abstract
This paper describes the embedding of ClassSheet models in spreadsheet systems. ClassSheet models are well-known and describe the business logic of spreadsheet data. We embed this domain specific model representation on the (general purpose) spreadsheet system. By defining such an embedding, we provide end users a model-driven engineering spreadsheet developing environment. End users can interact with both the model and the spreadsheet data in the same environment. Moreover, we use advanced techniques to evolve spreadsheets and models and to have them synchronized. In this paper we present our work on extending a widely used spreadsheet system with such a model-driven spreadsheet engineering environment.