| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Ouroboros.Network.Testing.Data.Signal
Synopsis
- data Events a
- eventsFromList :: [( Time , a)] -> Events a
- eventsFromListUpToTime :: Time -> [( Time , a)] -> Events a
- eventsToList :: Events a -> [( Time , a)]
- selectEvents :: (a -> Maybe b) -> Events a -> Events b
- primitiveTransformEvents :: ([ E a] -> [ E b]) -> Events a -> Events b
- data TS = TS ! Time ! Int
- data E a = E ! TS a
- data Signal a
- fromChangeEvents :: a -> Events a -> Signal a
- toChangeEvents :: Signal a -> Events a
- fromEvents :: Events a -> Signal ( Maybe a)
- signalProperty :: forall a. Int -> (a -> String ) -> (a -> Bool ) -> Signal a -> Property
- truncateAt :: Time -> Signal a -> Signal a
- stable :: Signal a -> Signal a
- nub :: Eq a => Signal a -> Signal a
- nubBy :: (a -> a -> Bool ) -> Signal a -> Signal a
- linger :: DiffTime -> (a -> Bool ) -> Signal a -> Signal Bool
- timeout :: forall a. DiffTime -> (a -> Bool ) -> Signal a -> Signal Bool
- until :: (a -> Bool ) -> (a -> Bool ) -> Signal a -> Signal Bool
- difference :: (a -> a -> b) -> Signal a -> Signal ( Maybe b)
- scanl :: (b -> a -> b) -> b -> Signal a -> Signal b
- keyedTimeout :: forall a b. Ord b => DiffTime -> (a -> Set b) -> Signal a -> Signal ( Set b)
- keyedLinger :: forall a b. Ord b => DiffTime -> (a -> Set b) -> Signal a -> Signal ( Set b)
- keyedUntil :: forall a b. Ord b => (a -> Set b) -> (a -> Set b) -> (a -> Bool ) -> Signal a -> Signal ( Set b)
Events
A time-ordered trace of discrete events that occur at specific times.
This corresponds for example to a trace of events or observations from a simulation.
eventsFromListUpToTime :: Time -> [( Time , a)] -> Events a Source #
Construct
Events
from a time series.
The time series is truncated at (but not including) the given time. This is necessary to check properties over finite prefixes of infinite time series.
eventsToList :: Events a -> [( Time , a)] Source #
Low level access
Signals
A signal is a time-varying value. It has a value at all times. It changes value at discrete times, i.e. it is not continuous.
Construction and conversion
fromChangeEvents :: a -> Events a -> Signal a Source #
Construct a
Signal
from an initial value and a time series of events
that represent new values of the signal.
This only makes sense for events that sample a single time-varying value.
toChangeEvents :: Signal a -> Events a Source #
Convert a
Signal
into a time series of events when the signal value
changes.
fromEvents :: Events a -> Signal ( Maybe a) Source #
Construct a
Signal
that represents a time series of discrete events. The
signal is
Just
the event value at the time of the event, and is
Nothing
at all other times.
Note that this signal "instantaneously" takes the event value and reverts
to
Nothing
before time moves on. Therefore this kind of signal is not
"stable" in the sense of
stableSignal
.
QuickCheck
signalProperty :: forall a. Int -> (a -> String ) -> (a -> Bool ) -> Signal a -> Property Source #
Check a property over a
Signal
. The property should be true at all times.
On failure it shows the
n
most recent signal values.
Simple signal transformations
stable :: Signal a -> Signal a Source #
A signal can change value more than once at a single point of time.
Sometimes we are interested only in the final "stable" value of the signal before time moves on. This function discards the other values, keeping only the final value at each time.
nub :: Eq a => Signal a -> Signal a Source #
Sometimes the way a signal is constructed leads to duplicate signal values
which can slow down signal processing. This tidies up the signal by
eliminating the duplicates. This does not change the meaning (provided the
Eq
instance is true equality).
Temporal operations
linger :: DiffTime -> (a -> Bool ) -> Signal a -> Signal Bool Source #
A linger signal remains
True
for the given time after the underlying
signal is
True
.
Arguments
| :: forall a. DiffTime |
timeout duration |
| -> (a -> Bool ) |
the arming function |
| -> Signal a | |
| -> Signal Bool |
Make a timeout signal, based on observing an underlying signal.
The timeout signal takes the value
True
when the timeout has occurred, and
False
otherwise.
The timeout is controlled by an "arming" function on the underlying signal.
The arming function should return
True
when the timeout should be started,
and it returns the time to wait before the timeout fires. The arming function
should return
False
when the timeout should be cancelled or not started.
The output signal becomes
True
when the arming function has been
continuously active (i.e. returning
True
) for the given duration.
Set-based temporal operations
Arguments
| :: forall a b. Ord b | |
| => DiffTime | |
| -> (a -> Set b) |
The timeout arming set signal |
| -> Signal a | |
| -> Signal ( Set b) |
Make a signal that says if a given event longed at least a certain time (timeout), based on observing an underlying signal.
The underlying signal is scrutinised with the provided "timeout arming" function that tells us if the signal value is interesting to track. If it is, we arm it with a timeout and see, if until the timeout goes off there's no other event to arm. If any activity occurs again before the previous timeout, then the timeout is reset with the new event and the other one is discarded.
Arguments
| :: forall a b. Ord b | |
| => DiffTime | |
| -> (a -> Set b) |
The activity set signal |
| -> Signal a | |
| -> Signal ( Set b) |
Make a signal that keeps track of recent activity, based on observing an underlying signal.
The underlying signal is scrutinised with the provided "activity interest" function that tells us if the signal value is activity of interest to track. If it is, the given key is entered into the result signal set for the given time duration. If the same activity occurs again before the duration expires then the expiry will be extended to the new deadline (it is not cumulative). The key will be removed from the result signal set when it expires.