Utils module
============
This module contains some functions that might make it into the core library eventually.
> module Common.Utils where
>
> import Control.Applicative
> import Control.Monad
> import FRP.Elerea.Param
>
> import Common.Vector
The `driveNetwork` function simply executes the supersteps while the
`driver` function keeps returning valid delta time values.
> driveNetwork network driver = do
> dt <- driver
> case dt of
> Just dt -> do join (network dt)
> driveNetwork network driver
> Nothing -> return ()
A scalar integral function for `Fractional` instances.
> integral v0 s = transfer v0 (\dt v v0 -> v0+v*realToFrac dt) s
An integral function for two-dimensional vectors defined in the
`Vector` module.
> integralVec v0 s = transfer v0 (\dt v v0 -> v0^+^(v^*.realToFrac dt)) s
A rising edge detector.
> edge s = do
> s' <- delay False s
> return $ s' >>= \x -> if x then return False else s
A latch that always remembers the last value of a `Maybe` signal
wrapped in `Just`.
> storeJust x0 s = transfer x0 store s
> where store _ Nothing x = x
> store _ (Just x) _ = x