1. A method comprising: extracting expressions from one or more existing applications associated with a first data feed, wherein the extracted expressions satisfy an applicability criterion relative to a second data feed; generating one or more new applications to evaluate data from the second data feed, wherein the one or more new applications include the extracted expressions; and adjusting availability of individual ones of the new applications based on feedback received from usage of the one or more of the new applications in association with the second data feed.