A method, system and computer readable program product are disclosed for compiling a spreadsheet to execute stream processing in a computing system. In an embodiment, the method comprises extracting a function from the spreadsheet, said function supporting data windows and stream partitioning in the computing system; and identifying input cells of the spreadsheet for holding input values for the function, and identifying output cells of the spreadsheet for holding output values of the function. In embodiments of the invention, a data stream is partitioned into a plurality of data stream partitions, and the extracted function is applied to the stream partitions in parallel. In embodiments of the invention, the extracted function is applied to the data stream partitions in series. The windows may be time based windows, and may be count based windows, and the windows may have variable sizes.