Yampa-0.10.5: Library for programming hybrid systems.

Copyright(c) Antony Courtney and Henrik Nilsson, Yale University, 2003
LicenseBSD-style (see the LICENSE file in the distribution)
Portabilitynon-portable (GHC extensions)
Safe HaskellNone








reactimate Source


:: IO a

IO initialization action

-> (Bool -> IO (DTime, Maybe a))

IO input sensing action

-> (Bool -> b -> IO Bool)

IO actuaction (output processing) action

-> SF a b

Signal function

-> IO () 

Convenience function to run a signal function indefinitely, using a IO actions to obtain new input and process the output.

This function first runs the initialization action, which provides the initial input for the signal transformer at time 0.

Afterwards, an input sensing action is used to obtain new input (if any) and the time since the last iteration. The argument to the input sensing function indicates if it can block. If no new input is received, it is assumed to be the same as in the last iteration.

After applying the signal function to the input, the actuation IO action is executed. The first argument indicates if the output has changed, the second gives the actual output). Actuation functions may choose to ignore the first argument altogether. This action should return True if the reactimation must stop, and False if it should continue.

Note that this becomes the program's main loop, which makes using this function incompatible with GLUT, Gtk and other graphics libraries. It may also impose a sizeable constraint in larger projects in which different subparts run at different time steps. If you need to control the main loop yourself for these or other reasons, use reactInit and react.

type ReactHandle a b = IORef (ReactState a b) Source

A reference to reactimate's state, maintained across samples.

reactInit :: IO a -> (ReactHandle a b -> Bool -> b -> IO Bool) -> SF a b -> IO (ReactHandle a b) Source

Initialize a top-level reaction handle.

react :: ReactHandle a b -> (DTime, Maybe a) -> IO Bool Source

Process a single input sample.


embed :: SF a b -> (a, [(DTime, Maybe a)]) -> [b] Source

Given a signal function and a pair with an initial input sample for the input signal, and a list of sampling times, possibly with new input samples at those times, it produces a list of output samples.

This is a simplified, purely-functional version of reactimate.

embedSynch :: SF a b -> (a, [(DTime, Maybe a)]) -> SF Double b Source

Synchronous embedding. The embedded signal function is run on the supplied input and time stream at a given (but variable) ratio >= 0 to the outer time flow. When the ratio is 0, the embedded signal function is paused.

deltaEncode :: Eq a => DTime -> [a] -> (a, [(DTime, Maybe a)]) Source

Spaces a list of samples by a fixed time delta, avoiding unnecessary samples when the input has not changed since the last sample.

deltaEncodeBy :: (a -> a -> Bool) -> DTime -> [a] -> (a, [(DTime, Maybe a)]) Source

deltaEncode parameterized by the equality test.