_Reactive_ [1] is a simple foundation for programming reactive systems functionally. Like Fran/FRP, it has a notions of (reactive) behaviors and events. Like DataDriven [2], Reactive has a data-driven implementation. The main difference between Reactive and DataDriven is that Reactive builds on MVar-based "futures", while DataDriven builds on continuation-based computations. The inspiration for Reactive was Mike Sperber's Lula [3] implementation of FRP. Mike used blocking threads, which I had never considered for FRP. While playing with the idea, I realized that I could give a very elegant and efficient solution to caching, which DataDriven doesn't do. (For an application "f <*> a" of a varying function to a varying argument, caching remembers the latest function to apply to a new argument and the last argument to which to apply a new function.) Please share any comments & suggestions on the discussion (talk) page there. You can configure, build, and install all in the usual way with Cabal commands. runhaskell Setup.lhs configure runhaskell Setup.lhs build runhaskell Setup.lhs install References: [1] http://haskell.org/haskellwiki/Reactive [2] http://haskell.org/haskellwiki/DataDriven [3] http://www-pu.informatik.uni-tuebingen.de/lula/deutsch/publications.html