Safe Haskell | None |
---|---|

Language | Haskell2010 |

## Synopsis

- timeInfo :: Monad m => ClSF m cl a (TimeInfo cl)
- timeInfoOf :: Monad m => (TimeInfo cl -> b) -> ClSF m cl a b
- sinceLastS :: Monad m => ClSF m cl a (Diff (Time cl))
- sinceInitS :: Monad m => ClSF m cl a (Diff (Time cl))
- absoluteS :: Monad m => ClSF m cl a (Time cl)
- tagS :: Monad m => ClSF m cl a (Tag cl)
- sinceStart :: (Monad m, TimeDomain time) => BehaviourF m time a (Diff time)
- (>->) :: Category cat => cat a b -> cat b c -> cat a c
- (<-<) :: Category cat => cat b c -> cat a b -> cat a c
- arr_ :: Arrow a => b -> a c b
- clId :: Monad m => ClSF m cl a a
- integralFrom :: (Monad m, VectorSpace v s, s ~ Diff td) => v -> BehaviorF m td v v
- integral :: (Monad m, VectorSpace v s, s ~ Diff td) => BehaviorF m td v v
- derivativeFrom :: (Monad m, VectorSpace v s, s ~ Diff td) => v -> BehaviorF m td v v
- derivative :: (Monad m, VectorSpace v s, s ~ Diff td) => BehaviorF m td v v
- threePointDerivativeFrom :: (Monad m, VectorSpace v s, s ~ Diff td) => v -> BehaviorF m td v v
- threePointDerivative :: (Monad m, VectorSpace v s, s ~ Diff td) => BehaviorF m td v v
- weightedAverageFrom :: (Monad m, VectorSpace v s, s ~ Diff td) => v -> BehaviorF m td (v, s) v
- averageFrom :: (Monad m, VectorSpace v s, Floating s, s ~ Diff td) => v -> Diff td -> BehaviorF m td v v
- average :: (Monad m, VectorSpace v s, Floating s, s ~ Diff td) => Diff td -> BehaviourF m td v v
- averageLinFrom :: (Monad m, VectorSpace v s, s ~ Diff td) => v -> Diff td -> BehaviourF m td v v
- averageLin :: (Monad m, VectorSpace v s, s ~ Diff td) => Diff td -> BehaviourF m td v v
- lowPass :: (Monad m, VectorSpace v s, Floating s, s ~ Diff td) => Diff td -> BehaviourF m td v v
- highPass :: (Monad m, VectorSpace v s, Floating s, s ~ Diff td) => Diff td -> BehaviourF m td v v
- bandPass :: (Monad m, VectorSpace v s, Floating s, s ~ Diff td) => Diff td -> BehaviourF m td v v
- bandStop :: (Monad m, VectorSpace v s, Floating s, s ~ Diff td) => Diff td -> BehaviourF m td v v
- keepFirst :: Monad m => ClSF m cl a a
- historySince :: (Monad m, Ord (Diff (Time cl)), TimeDomain (Time cl)) => Diff (Time cl) -> ClSF m cl a (Seq (TimeInfo cl, a))
- delayBy :: (Monad m, Ord (Diff td), TimeDomain td) => Diff td -> BehaviorF m td a a
- timer :: (Monad m, TimeDomain td, Ord (Diff td)) => Diff td -> BehaviorF (ExceptT () m) td a (Diff td)
- timer_ :: (Monad m, TimeDomain td, Ord (Diff td)) => Diff td -> BehaviorF (ExceptT () m) td a ()
- scaledTimer :: (Monad m, TimeDomain td, Fractional (Diff td), Ord (Diff td)) => Diff td -> BehaviorF (ExceptT () m) td a (Diff td)
- lastS :: Monad m => a -> MSF m (Maybe a) a

# Read time information

timeInfo :: Monad m => ClSF m cl a (TimeInfo cl) Source #

Read the environment variable, i.e. the `TimeInfo`

.

timeInfoOf :: Monad m => (TimeInfo cl -> b) -> ClSF m cl a b Source #

Utility to apply functions to the current `TimeInfo`

,
such as record selectors:
```
printAbsoluteTime :: ClSF IO cl () ()
printAbsoluteTime = timeInfoOf absolute >>> arrMCl print
```

sinceLastS :: Monad m => ClSF m cl a (Diff (Time cl)) Source #

Continuously return the time difference since the last tick.

sinceInitS :: Monad m => ClSF m cl a (Diff (Time cl)) Source #

Continuously return the time difference since clock initialisation.

sinceStart :: (Monad m, TimeDomain time) => BehaviourF m time a (Diff time) Source #

Calculate the time passed since this `ClSF`

was instantiated.
This is _not_ the same as `sinceInitS`

,
which measures the time since clock initialisation.

For example, the following gives a sawtooth signal:

sawtooth = safely $ do try $ sinceStart >>> proc time -> do throwOn () -time 1 returnA -< time safe sawtooth

If you replace `sinceStart`

by `sinceInitS`

,
it will usually hang after one second,
since it doesn't reset after restarting the sawtooth.

# Useful aliases

(>->) :: Category cat => cat a b -> cat b c -> cat a c infixr 6 Source #

Alias for `>>>`

(sequential composition)
with higher operator precedence, designed to work with the other operators, e.g.:

clsf1 >-> clsf2 @@ clA ||@ sched @|| clsf3 >-> clsf4 @@ clB

The type signature specialises e.g. to

(>->) :: Monad m => ClSF m cl a b -> ClSF m cl b c -> ClSF m cl a c

arr_ :: Arrow a => b -> a c b Source #

Output a constant value. Specialises e.g. to this type signature:

arr_ :: Monad m => b -> ClSF m cl a b

# Basic signal processing components

## Integration and differentiation

integralFrom :: (Monad m, VectorSpace v s, s ~ Diff td) => v -> BehaviorF m td v v Source #

The output of `integralFrom v0`

is the numerical Euler integral
of the input, with initial offset `v0`

.

integral :: (Monad m, VectorSpace v s, s ~ Diff td) => BehaviorF m td v v Source #

Euler integration, with zero initial offset.

derivativeFrom :: (Monad m, VectorSpace v s, s ~ Diff td) => v -> BehaviorF m td v v Source #

The output of `derivativeFrom v0`

is the numerical derivative of the input,
with a Newton difference quotient.
The input is initialised with `v0`

.

derivative :: (Monad m, VectorSpace v s, s ~ Diff td) => BehaviorF m td v v Source #

Numerical derivative with input initialised to zero.

threePointDerivativeFrom Source #

:: (Monad m, VectorSpace v s, s ~ Diff td) | |

=> v | The initial position |

-> BehaviorF m td v v |

Like `derivativeFrom`

, but uses three samples to compute the derivative.
Consequently, it is delayed by one sample.

threePointDerivative :: (Monad m, VectorSpace v s, s ~ Diff td) => BehaviorF m td v v Source #

Like `threePointDerivativeFrom`

,
but with the initial position initialised to `zeroVector`

.

## Averaging and filters

:: (Monad m, VectorSpace v s, s ~ Diff td) | |

=> v | The initial position |

-> BehaviorF m td (v, s) v |

A weighted moving average signal function. The output is the average of the first input, weighted by the second input (which is assumed to be always between 0 and 1). The weight is applied to the average of the last tick, so a weight of 1 simply repeats the past value unchanged, whereas a weight of 0 outputs the current value.

:: (Monad m, VectorSpace v s, Floating s, s ~ Diff td) | |

=> v | The initial position |

-> Diff td | The time scale on which the signal is averaged |

-> BehaviorF m td v v |

An exponential moving average, or low pass.
It will average out, or filter,
all features below a given time constant `t`

.
(Equivalently, it filters out frequencies above `1 / (2 * pi * t)`

.)

:: (Monad m, VectorSpace v s, Floating s, s ~ Diff td) | |

=> Diff td | The time scale on which the signal is averaged |

-> BehaviourF m td v v |

An average, or low pass, initialised to zero.

:: (Monad m, VectorSpace v s, s ~ Diff td) | |

=> v | The initial position |

-> Diff td | The time scale on which the signal is averaged |

-> BehaviourF m td v v |

A linearised version of `averageFrom`

.
It is more efficient, but only accurate
if the supplied time scale is much bigger
than the average time difference between two ticks.

:: (Monad m, VectorSpace v s, s ~ Diff td) | |

=> Diff td | The time scale on which the signal is averaged |

-> BehaviourF m td v v |

Linearised version of `average`

.

### First-order filters

lowPass :: (Monad m, VectorSpace v s, Floating s, s ~ Diff td) => Diff td -> BehaviourF m td v v Source #

Alias for `average`

.

:: (Monad m, VectorSpace v s, Floating s, s ~ Diff td) | |

=> Diff td | The time constant |

-> BehaviourF m td v v |

Filters out frequencies below `1 / (2 * pi * t)`

.

:: (Monad m, VectorSpace v s, Floating s, s ~ Diff td) | |

=> Diff td | The time constant |

-> BehaviourF m td v v |

Filters out frequencies other than `1 / (2 * pi * t)`

.

:: (Monad m, VectorSpace v s, Floating s, s ~ Diff td) | |

=> Diff td | The time constant |

-> BehaviourF m td v v |

Filters out the frequency `1 / (2 * pi * t)`

.

# Delays

keepFirst :: Monad m => ClSF m cl a a Source #

Remembers and indefinitely outputs ("holds") the first input value.

:: (Monad m, Ord (Diff (Time cl)), TimeDomain (Time cl)) | |

=> Diff (Time cl) | The size of the time window |

-> ClSF m cl a (Seq (TimeInfo cl, a)) |

Remembers all input values that arrived within a given time window. New values are appended left.

:: (Monad m, Ord (Diff td), TimeDomain td) | |

=> Diff td | The time span to delay the signal |

-> BehaviorF m td a a |

Delay a signal by certain time span, initialising with the first input.

# Timers

timer :: (Monad m, TimeDomain td, Ord (Diff td)) => Diff td -> BehaviorF (ExceptT () m) td a (Diff td) Source #

Throws an exception after the specified time difference,
outputting the time passed since the `timer`

was instantiated.

timer_ :: (Monad m, TimeDomain td, Ord (Diff td)) => Diff td -> BehaviorF (ExceptT () m) td a () Source #

Like `timer_`

, but doesn't output the remaining time at all.

scaledTimer :: (Monad m, TimeDomain td, Fractional (Diff td), Ord (Diff td)) => Diff td -> BehaviorF (ExceptT () m) td a (Diff td) Source #

Like `timer`

, but divides the remaining time by the total time.