| Copyright | (c) Ivan Perez 2019-2022 (c) Ivan Perez and Manuel Baerenz 2016-2018 |
|---|---|
| License | BSD3 |
| Maintainer | ivan.perez@keera.co.uk |
| Safe Haskell | Safe-Inferred |
| Language | Haskell2010 |
FRP.BearRiver.Switches
Description
Switches allow you to change the signal function being applied.
The basic idea of switching is formed by combining a subordinate signal function and a signal function continuation parameterised over some initial data.
Synopsis
- switch :: Monad m => SF m a (b, Event c) -> (c -> SF m a b) -> SF m a b
- dSwitch :: Monad m => SF m a (b, Event c) -> (c -> SF m a b) -> SF m a b
- parB :: Monad m => [SF m a b] -> SF m a [b]
- dpSwitchB :: (Functor m, Monad m, Traversable col) => col (SF m a b) -> SF m (a, col b) (Event c) -> (col (SF m a b) -> c -> SF m a (col b)) -> SF m a (col b)
- parC :: Monad m => SF m a b -> SF m [a] [b]
Basic switching
switch :: Monad m => SF m a (b, Event c) -> (c -> SF m a b) -> SF m a b Source #
Basic switch.
By default, the first signal function is applied. Whenever the second value in the pair actually is an event, the value carried by the event is used to obtain a new signal function to be applied *at that time and at future times*. Until that happens, the first value in the pair is produced in the output signal.
Important note: at the time of switching, the second signal function is applied immediately. If that second SF can also switch at time zero, then a double (nested) switch might take place. If the second SF refers to the first one, the switch might take place infinitely many times and never be resolved.
Remember: The continuation is evaluated strictly at the time of switching!
dSwitch :: Monad m => SF m a (b, Event c) -> (c -> SF m a b) -> SF m a b Source #
Switch with delayed observation.
By default, the first signal function is applied.
Whenever the second value in the pair actually is an event, the value carried by the event is used to obtain a new signal function to be applied *at future times*.
Until that happens, the first value in the pair is produced in the output signal.
Important note: at the time of switching, the second signal function is used immediately, but the current input is fed by it (even though the actual output signal value at time 0 is discarded).
If that second SF can also switch at time zero, then a double (nested) switch might take place. If the second SF refers to the first one, the switch might take place infinitely many times and never be resolved.
Remember: The continuation is evaluated strictly at the time of switching!
Parallel composition/switching (collections)
With broadcasting
parB :: Monad m => [SF m a b] -> SF m a [b] Source #
Spatial parallel composition of a signal function collection. Given a
collection of signal functions, it returns a signal function that broadcasts
its input signal to every element of the collection, to return a signal
carrying a collection of outputs. See par.
For more information on how parallel composition works, check https://www.antonycourtney.com/pubs/hw03.pdf
dpSwitchB :: (Functor m, Monad m, Traversable col) => col (SF m a b) -> SF m (a, col b) (Event c) -> (col (SF m a b) -> c -> SF m a (col b)) -> SF m a (col b) Source #
Decoupled parallel switch with broadcasting (dynamic collection of signal
functions spatially composed in parallel). See dpSwitch.
For more information on how parallel composition works, check https://www.antonycourtney.com/pubs/hw03.pdf
Parallel composition/switching (lists)
With replication
parC :: Monad m => SF m a b -> SF m [a] [b] Source #
Apply an SF to every element of a list.
Example:
>>>embed (parC integral) (deltaEncode 0.1 [[1, 2], [2, 4], [3, 6], [4.0, 8.0 :: Float]])[[0.0,0.0],[0.1,0.2],[0.3,0.6],[0.6,1.2]]
The number of SFs or expected inputs is determined by the first input list, and not expected to vary over time.
If more inputs come in a subsequent list, they are ignored.
>>>embed (parC (arr (+1))) (deltaEncode 0.1 [[0], [1, 1], [3, 4], [6, 7, 8], [1, 1], [0, 0], [1, 9, 8]])[[1],[2],[4],[7],[2],[1],[2]]
If less inputs come in a subsequent list, an exception is thrown.
>>>embed (parC (arr (+1))) (deltaEncode 0.1 [[0, 0], [1, 1], [3, 4], [6, 7, 8], [1, 1], [0, 0], [1, 9, 8]])[[1,1],[2,2],[4,5],[7,8],[2,2],[1,1],[2,10]]