Abstract. The spreadsheet paradigm offers a fast interactive loop, where the effects of updates to definitions and data are immediately visible. This makes the paradigm attractive for program development, where redefinitions can be immediately tested and the results displayed. We have designed a simple, compilerindependent spreadsheet interface to Haskell, where cells host Haskell definitions. Spreadsheets are also used for high-level array calculations. In order to meet that demand we have designed and implemented an extended array library for Haskell, which provides a number of typical array-language facilities. Together, the interface and the array library provide an interactive environment that can be used both for development of general Haskell code and for array-oriented spreadsheet calculations.

. Data fields provide a flexible and highly general model for indexed collections of data. Data Field Haskell is a dialect of the functional language Haskell which provides an instance of data fields. We describe Data Field Haskell and exemplify how it can be used in the early phase of parallel program design. 1 Introduction Many computing applications require indexed data structures. The canonical indexed data structure is the array. However, for sparse, distributed applications, other, more dynamic indexed data structures are needed. It is desirable to develop such algorithms on a high level first, in order to get them right, since the low level data representations can be intricate. Data Field Haskell provides an instance of data fields -- a data type for general indexed structures. This Haskell dialect can be used for rapid prototyping of parallel computational algorithms which may involve sparse structures. Various versions of the data field model have been described elsew...