Rhine is a library for synchronous and asynchronous Functional Reactive Programming (FRP). It separates the aspects of clocking, scheduling and resampling from each other, and ensures clock-safety on the type level. Signal processing units can be annotated by clocks, which hold the information when data will be input, processed and output. Different components of the signal network will become active at different times, or work at different rates. To schedule the components and allow them to communicate, several standard scheduling and resampling solutions are implemented. Own schedules and resampling buffers can be implemented in a reusable fashion. A (synchronous) program outputting "Hello World!" every tenth of a second looks like this: flow $ constMCl (putStrLn "Hello World!") @@ (waitClock :: Millisecond 100)