Yampa/reactimate

reactimate :: IO a                          -- init
           -> (Bool -> IO (DTime, Maybe a)) -- input/sense
           -> (Bool -> b -> IO Bool)        -- output/actuate
           -> SF a b                        -- process/signal function
           -> IO ()

'reactimate' basically is an input-process-output loop. Keep in mind that the signal function may take pretty complex forms like a parallel switch embedded in a loop.

(The 'Bool' parameter of 'input' and 'output' are unused if you look up the definition of reactimate so just ignore them.)